Medroxyprogesterone Acetate (medroxyprogesterone acetate)

No dosing information is available for this tab.

Medroxyprogesterone acetate (alone or in fixed combination with estrogens (i.e., conjugated estrogens, estradiol cypionate)) is administered orally, subcutaneously, or IM. When used as a contraceptive in females, medroxyprogesterone acetate is administered subcutaneously or IM; the drug is administered subcutaneously for the management of pain associated with endometriosis. Medroxyprogesterone acetate is administered IM in the treatment of cancer or male sexual deviance+ (paraphilia). Because of the prolonged action, parenteral administration of the drug is not recommended for the treatment of secondary amenorrhea or abnormal uterine bleeding.

Medroxyprogesterone acetate injectable suspension (containing medroxyprogesterone acetate alone or in fixed combination with estradiol cypionate) must be vigorously shaken immediately before each use to ensure complete suspension of the drug(s). IM injection of medroxyprogesterone acetate alone (Depo-Provera(R) Contraceptive, Depo-Provera(R), Medroxyprogesterone Acetate Contraceptive) or in combination with estradiol cypionate (Lunelle(R) Monthly Contraceptive) should be made deep into the gluteal, deltoid, or anterior thigh muscle. Subcutaneous injection of medroxyprogesterone acetate (depo-subQ provera 104(R)) is made into the anterior thigh or abdomen; the preparation for subcutaneous administration should not be administered IM.

Oral dosage preparations containing medroxyprogesterone acetate in combination with conjugated estrogens as monophasic or biphasic regimens are commercially available in a mnemonic dispensing package that is designed to aid the user in complying with the prescribed dosage schedule. The monophasic combination (Prempro(R)) is available in a 28-day dosage preparation that contains 28 tablets of conjugated estrogens (0.625 mg) in fixed combination with medroxyprogesterone acetate (2.5 or 5 mg). The monophasic combination (Prempro(R)) also is available in a 28-day dosage preparation that contains 28 tablets of conjugated estrogens USP (0.3 or 0.45 mg) in fixed combination with medroxyprogesterone acetate (1.5 mg). The biphasic combination (Premphase(R)) also is available in a 28-day dosage preparation that contains 14 tablets of conjugated estrogens (0.625 mg) and 14 tablets of conjugated estrogens (0.625 mg) in fixed combination with medroxyprogesterone acetate (5 mg).

There is no enhanced messaging for this drug.

Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

Agents Affecting Plasma Cortisol Levels/Cosyntropin

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Agents affecting plasma cortisol levels may impact the accuracy of the cosyntropin diagnostic test.(1)

CLINICAL EFFECTS: Concurrent use of agents affecting plasma cortisol levels may impact the accuracy of the cosyntropin diagnostic test.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of cosyntropin states accuracy of diagnosis using the cosyntropin diagnostic test may be complicated by concomitant medications affecting plasma cortisol levels.(1) Agents affecting plasma cortisol levels and recommendation to stop prior to cosyntropin diagnostic test include: - Glucocorticoids: May elevate plasma cortisol levels. Stop these drugs on the day of testing. Long-acting glucocorticoids may need to be stopped for a longer period before testing. - Spironolactone: May elevate plasma cortisol levels. Stop spironolactone on the day of testing. - Estrogen: May elevate plasma total cortisol levels. Discontinue estrogen containing drugs 4 to 6 weeks prior to testing to allow cortisol binding globulin levels to return to levels within the reference range. Alternatively, concomitant measurement of cortisol binding globulin at the time of testing can be done; if cortisol binding globulin levels are elevated, plasma total cortisol levels are considered inaccurate.(1)

DISCUSSION: Concurrent use of agents affecting plasma cortisol levels may impact the accuracy of the cosyntropin diagnostic test.(1)

Hormonal Contraceptives/Dipyrone

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Dipyrone is a moderate CYP3A4 and weak CYP2C9 inducer. Coadministration of dipyrone with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1-2)

CLINICAL EFFECTS: Concurrent use of dipyrone may reduce the effectiveness of hormonal contraceptives, except for intrauterine systems containing levonorgestrel.(1-2)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Avoid concomitant use with hormonal contraceptives except for intrauterine systems containing levonorgestrel. If contraception is needed or desired, an alternate contraceptive that is not affected by CYP inducers (e.g., an intrauterine system) or additional non-hormonal contraceptives (e.g., condoms) should be used when treated concomitantly with dipyrone and for at least 4 weeks after the last dose of dipyrone.(1) Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(3)

DISCUSSION: Dipyrone is a moderate CYP3A4 and weak CYP2C9 inducer.(1-2) In a study, dipyrone 1 gram 3 times daily decreased the area under curve (AUC) of midazolam (a CYP3A4 substrate) by 68% and of flurbiprofen (a CYP2C9 substrate) by 22%.(2)

Hormonal Contraceptives/Elafibranor

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Elafibranor is a weak CYP3A4 inducer. Coadministration of elafibranor with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1)

CLINICAL EFFECTS: Concurrent use of elafibranor may reduce the effectiveness of hormonal contraceptives.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid concomitant use of hormonal contraceptives with elafibranor. Advise females of reproductive potential to use effective non-hormonal contraception (e.g., non-hormonal intrauterine system) or additional non-hormonal contraceptive (e.g., condoms) during treatment with elafibranor and for 21 days after the last dose. Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(2)

DISCUSSION: Elafibranor is a weak CYP3A4 inducer.(1) Coadministration of elafibranor with simvastatin (a CYP3A, OATP1B1, and OATP1B3 substrate) decreased the concentration maximum (Cmax) and area-under-curve (AUC) of simvastatin beta-hydroxyacid by 26% and 32%, respectively.(1)

Hormonal Contraceptives/Mavacamten

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Mavacamten is a moderate CYP3A4 inducer. Coadministration of mavacamten with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1)

CLINICAL EFFECTS: Concurrent use of mavacamten can lead to ineffective hormonal contraceptive and cause unintended pregnancy. Mavacamten may cause fetal harm when administered to a pregnant woman.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid concomitant use of hormonal contraceptives with mavacamten. Advise females of reproductive potential to use effective non-hormonal contraception during treatment with mavacamten and for 4 months after the last dose.(1) Hormonal contraceptives containing a combination of ethinyl estradiol and norethindrone may be used with mavacamten.(1) Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Pregnant women and females of reproductive potential should be counseled on the potential risk to the fetus.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (i.e., a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(3)

DISCUSSION: Mavacamten is a moderate CYP3A4 inducer.(1) Concurrent use of a 16-day course of mavacamten (25 mg on days 1 and 2, followed by 15 mg for 14 days) resulted in a decrease in midazolam area-under-curve (AUC) and concentration maximum (Cmax) by 13% and 7%, respectively, in healthy CYP2C19 normal metabolizers. Concurrent use of mavacamten once daily in patients with hypertrophic cardiomyopathy, midazolam AUC and Cmax are predicted to decrease by 21 to 64% and 13 to 48%, respectively, depending on the dose of mavacamten and CYP2C19 phenotype.(1) Mavacamten has not been studied with hormonal contraceptives. It can render some hormonal contraceptives ineffective and may cause unintended pregnancy. Women should use non-hormonal contraception during therapy.(1) In an animal reproduction study, mavacamten administration resulted in decreases in mean fetal body weight, reductions in fetal ossification of bones, and increases in post-implantation loss as well as increases in skeletal malformations at doses similar to maximum recommended human doses.(1)

Hormonal Contraceptives/Mobocertinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Mobocertinib is a weak CYP3A4 inducer. Coadministration of mobocertinib with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1)

CLINICAL EFFECTS: Concurrent use of mobocertinib can lead to ineffective hormonal contraceptive and cause fetal harm when administered to a pregnant woman.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid concomitant use of hormonal contraceptives with mobocertinib. Advise females of reproductive potential to use effective non-hormonal contraception during treatment with mobocertinib and for 1 month after the last dose. Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Pregnant women and females of reproductive potential should be counseled on the potential risk to a fetus.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(2)

DISCUSSION: Mobocertinib has not been studied with hormonal contraceptives. It can render some hormonal contraceptives ineffective and cause embryo-fetal harm. Women should use non-hormonal contraception during therapy and for one month after the last dose.(1) In an animal study, oral administration of mobocertinib to pregnant rats during the period of organogenesis resulted in embryolethality at maternal exposures approximately 1.7 times the human exposure based on area under the curve (AUC) at the 160 mg once daily clinical dose.(1) Coadministration of mobocertinib 160 mg once daily with oral or intravenous midazolam (a CYP3A substrate) decreased the AUC of midazolam by 32% and 16%, respectively.(1)

Hormonal Contraceptives/Omaveloxolone

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Omaveloxolone is a weak CYP3A4 inducer. Coadministration of omaveloxolone with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1)

CLINICAL EFFECTS: Concurrent use of omaveloxolone may reduce the effectiveness of hormonal contraceptives.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid concomitant use of hormonal contraceptives with omaveloxolone. Advise females of reproductive potential to use effective non-hormonal contraception (e.g., non-hormonal intrauterine system) or additional non-hormonal contraceptive (e.g., condoms) during treatment with omaveloxolone and for 28 days after the last dose. Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(2)

DISCUSSION: Coadministration of omaveloxolone with midazolam (a CYP3A substrate) decreased the area-under-curve (AUC) of midazolam by 45%.(1)

Hormonal Contraceptives/Pacritinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Pacritinib is a moderate CYP3A4 inducer. Coadministration of pacritinib with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1)

CLINICAL EFFECTS: Concurrent use of pacritinib may reduce the effectiveness of hormonal contraceptives, except for intrauterine systems containing levonorgestrel.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of pacritinib states to avoid concomitant use with hormonal contraceptives except for intrauterine systems containing levonorgestrel. If contraception is needed or desired, an alternate contraceptive that is not affected by CYP3A4 inducers (e.g., an intrauterine system) or additional non-hormonal contraceptives (e.g., condoms) should be used when treated concomitantly with pacritinib and for 30 days after the last dose of pacritinib.(1) Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(2)

DISCUSSION: Pacritinib is a moderate CYP3A4 inducer.(1) Coadministration of pacritinib (200 mg twice daily at steady state) with a single dose of oral midazolam (2 mg) (a CYP3A4 substrate) decreased the concentration maximum (Cmax) and area-under-curve (AUC) of midazolam by 60% and 60%, respectively.(1)

Hormonal Contraceptives/Pexidartinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Pexidartinib is a moderate CYP3A4 inducer and may increase the CYP3A4-mediated metabolism of both estrogen and progestin components of hormonal contraceptives.(1)

CLINICAL EFFECTS: Coadministration of pexidartinib with hormonal contraceptives can result in decreased concentrations and reduced efficacy.(1) Breakthrough bleeding and contraceptive failure/pregnancy may result. Pexidartinib may cause fetal harm if administered to pregnant women.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of pexidartinib recommends that female patients of reproductive potential use effective non-hormonal contraception during treatment with pexidartinib and for 1 month after the final dose.(1) Patients should be alerted to the risk for decreased effectiveness(e.g. contraceptive failure) of their hormonal contraceptive therapy. For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (i.e., a copper IUD).(2)

DISCUSSION: Coadministration of pexidartinib 400 mg twice daily with oral midazolam, a sensitive CYP3A4 substrate, in patients decreased midazolam area-under-curve (AUC) by 59% and maximum concentration (Cmax) by 28%.(1)

Hormonal Contraceptives/Sunvozertinib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Sunvozertinib is a weak CYP3A4 inducer. Coadministration of sunvozertinib with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1)

CLINICAL EFFECTS: Concurrent use of sunvozertinib may reduce the effectiveness of hormonal contraceptives, except for intrauterine systems containing levonorgestrel.(1)

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: The manufacturer of sunvozertinib states to avoid concomitant use with hormonal contraceptives. Use a non-hormonal contraceptive during treatment and for 2 weeks after the last dose.(1) Women of reproductive age should be counseled to use highly effective contraception due to the risk of fetal harm with sunvozertinib. Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral, implantable, injectable, or transdermal agents) for contraception because they may not be effective.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(2)

DISCUSSION: Sunvozertinib is a weak CYP3A4 inducer.(1) Coadministration of sunvozertinib with midazolam (a CYP3A4 substrate) decreased the concentration maximum (Cmax) and area-under-curve (AUC) of midazolam by 15% and 23%, respectively.(1)

Hormonal Contraceptives/Vorasidenib

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Vorasidenib may induce the CYP3A4-mediated metabolism of hormonal contraceptives.(1) Hormonal contraceptives may inhibit the CYP1A2-mediated metabolism of vorasidenib.(1,2)

CLINICAL EFFECTS: Concurrent use of vorasidenib may reduce the blood concentrations and effectiveness of hormonal contraceptives. Vorasidenib may cause fetal harm when administered to pregnant women.(1) Concurrent use of moderate CYP1A2 inhibitors such as hormonal contraceptives may result in elevated levels of and effects from vorasidenib, including hepatotoxicity.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of vorasidenib states that concurrent use of moderate CYP1A2 inhibitors should be avoided. If concurrent use of moderate CYP1A2 inhibitors cannot be avoided, monitor for increased risk of adverse reactions and modify the dose of vorasidenib as recommended in the prescribing information.(1) Women of reproductive age should be counseled to avoid hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) due to the risk of contraceptive failure. Women should use an effective non-hormonal method of contraception during and for 3 months after vorasidenib therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (i.e., a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(3)

DISCUSSION: Vorasidenib is an inducer of CYP3A4 in vitro. Concomitant use of multiple doses of vorasidenib is predicted to decrease the concentration of CYP3A4 substrates, including hormonal contraceptives. Vorasidenib may cause fetal harm when administered to pregnant women.(1) Vorasidenib is primarily metabolized by CYP1A2. In a study, concurrent use of vorasidenib and ciprofloxacin (a moderate CYP1A2 inhibitor) increased vorasidenib Cmax 1.3-fold and AUC 2.5-fold.(1)

Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

Contraceptives/Chloramphenicol

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Estrogens and progesterones are extensively excreted in bile, principally as glycuronide conjugates. Subsequently, they undergo enterohepatic circulation where bacterial hydrolysis occurs, allowing for reabsorption of the oral contraceptives through the bowel wall and eventual urinary excretion. Treatment with antibiotics destroys the gut flora and prevents steroid reabsorption, resulting in lower than normal concentrations of the contraceptive and excretion via the feces rather than the urine. Chloramphenicol may also induce hepatic enzymes, resulting in increased metabolism of the contraceptive agent.

CLINICAL EFFECTS: May observe reduced pharmacologic effects of oral contraceptives with resultant breakthrough bleeding and pregnancy. Reduced effects may be seen for several days after discontinuation of antibiotic therapy.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: It is recommended that additional forms of birth control be used during concurrent administration of short courses of chloramphenicol. For longer courses, use another method of birth control. The patient should be asked to report any spotting or bleeding.

DISCUSSION: The manufacturer states that lower estrogen reabsorption and reduced efficacy may result in women taking oral contraceptives and chloramphenicol.

Contraceptives/Griseofulvin

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Unknown. However, possibly due to increased metabolism of oral contraceptives.

CLINICAL EFFECTS: Decreased effectiveness of oral contraceptives, producing breakthrough bleeding, amenorrhea and unintended pregnancy.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The patient should use an alternative method of contraception during and for one month after receiving griseofulvin. Increasing the dose of estrogen may be necessary in patients on low-dose estrogen. For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used an inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.

DISCUSSION: Loss of oral contraceptive efficacy has been reported following the addition of griseofulvin to the patient's drug therapy. Loss of efficacy was indicated by breakthrough bleeding, amenorrhea and unintended pregnancy.

Contraceptives/Troglitazone

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Troglitazone may induce the metabolism of the oral contraceptive by CYP3A4.(1,2)

CLINICAL EFFECTS: Concurrent administration may result in decreased levels of both the estrogen and progestin components of the oral contraceptive, which may result in breakthrough bleeding and loss of contraception.(1,2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Higher contraceptive dosages may be needed in patients receiving troglitazone therapy. Alternative methods of contraception should also be considered.(1,2) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(3)

DISCUSSION: In a study in 15 healthy women, concurrent troglitazone (600 mg daily) and Ortho Novum 1/35 (35 mcg ethinyl estradiol, 1 mg norethindrone) decreased the area-under-curve (AUC) and maximum concentration (Cmax) of ethinyl estradiol by 29% and 32%, respectively. Concurrent therapy decreased the AUC and Cmax of norethindrone by 30% and 31%. Troglitazone decreased the plasma unbound AUC of norethindrone by 49%.(1,2)

Contraceptives/Troleandomycin

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Troleandomycin is a strong CYP3A4 inhibitor and may decrease metabolism of oral contraceptives.(1,2) Increased exposure to estrogens may result in decreased bile acid secretion and toxic accumulation of bile acids.

CLINICAL EFFECTS: The concurrent use of troleandomycin with contraceptive agents may result in intrahepatic cholestasis.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid concurrent administration of these drugs.

DISCUSSION: Numerous case reports and one study document the occurrence of intrahepatic cholestasis in patients receiving oral contraceptives and troleandomycin concomitantly. This reaction appears to be reversible if the drugs are discontinued.

Hormonal Contraceptive Agents/Boceprevir

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Boceprevir may induce the metabolism of hormonal contraceptives by CYP3A4.

CLINICAL EFFECTS: Concurrent use of boceprevir and hormonal contraceptive agents may decrease the effectiveness of the hormonal contraceptive agent, which may result in contraceptive failure. Boceprevir is only indicated for use with ribavirin, a known teratogen.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women receiving boceprevir therapy should not rely on hormonal contraceptive agents (including oral, implantable, injectable, or transdermal agents) because they may not be effective. Two alternative effective methods of contraception (e.g. intrauterine devices and/or barrier methods) should be used during combination treatment with ribavirin and for six months after completing therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Concurrent use of boceprevir (800 mg three times daily for 7 days) decreased the area-under-curve (AUC) of ethinyl estradiol (administered as drospirenone/ethinyl estradiol 3/0.02 mg daily for 14 days) by 24%.(1) Concurrent use of boceprevir (800 mg three times daily for 21 days) decreased the AUC and maximum concentration (Cmax) of ethinyl estradiol (administered as norethindrone/ethinyl estradiol 1/0.035 mg daily for 21 days) by 26% and 21%, respectively. The AUC and Cmax of norethindrone decreased by 4% and 17%, respectively.(1)

Hormonal Contraceptive Agents/Bosentan

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Bosentan may induce the metabolism of hormonal contraceptive agents by CYP3A4.(1,2)

CLINICAL EFFECTS: Concurrent use of bosentan and hormonal contraceptive agents may decrease the effectiveness of the hormonal contraceptive agent, which may result in contraceptive failure.(1,2) Bosentan is likely to cause major birth defects if used by pregnant women.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women receiving bosentan therapy should not rely solely on hormonal contraceptive agents (including oral, implantable, injectable, or transdermal agents) because they may not be effective. Consider consulting a gynecologist or similar expert for advice on adequate contraception.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.

DISCUSSION: Concurrent use of bosentan and Ortho-Novum (norethindrone and ethinyl estradiol) resulted in average decreases of norethindrone and ethinyl estradiol by 14% and 31%, respectively. However, individual subjects experienced decreases in norethindrone and ethinyl estradiol by as much as 56% and 66%, respectively. Therefore, hormonal contraceptive agents may not be reliable in patients taking bosentan.(1,2)

Hormonal Contraceptive Agents/Clobazam

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Clobazam may induce the metabolism of hormonal contraceptive agents by CYP3A4.(1)

CLINICAL EFFECTS: Concurrent use of clobazam and hormonal contraceptive agents may decrease the effectiveness of the hormonal contraceptive agent, which may result in contraceptive failure. While there are no adequate studies in pregnant women, animal data suggests that clobazam use in pregnancy may result in development toxicity and fetal abnormalities.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women receiving clobazam therapy should not rely on hormonal contraceptive agents (including oral, implantable, injectable, or transdermal agents) because they may not be effective. Women taking clobazam should use additional, non-hormonal forms of contraception during and for 28 days after discontinuing clobazam.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Clobazam decreased the maximum concentration (Cmax) and area-under-curve (AUC) of midazolam, a CYP3A4 substrate by 24% and 27%, respectively. Because some hormonal contraceptives are metabolized by CYP3A4, clobazam use may decrease their effectiveness.(1)

Hormonal Contraceptive Agents/Dabrafenib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Dabrafenib may induce the metabolism of hormonal contraceptive agents by CYP3A4.(1)

CLINICAL EFFECTS: Concurrent use of dabrafenib and hormonal contraceptive agents may decrease the effectiveness of the hormonal contraceptive agent, which may result in contraceptive failure. Dabrafenib may cause birth defects and/or miscarriage if used by pregnant women.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women receiving dabrafenib therapy should not rely solely on hormonal contraceptive agents (including oral, implantable, injectable, or transdermal agents) because they may not be effective. Women should be advised to use a highly effective non-hormonal method of contraception during and for 2 weeks after dabrafenib mono-therapy.(1-3) The Canadian and UK manufacturers of dabrafenib also state that an effective method of contraception should be continued for 16 weeks after the last dose of trametinib when given in combination dabrafenib.(2-3) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(4)

DISCUSSION: Dabrafenib is a moderate inducer of CYP3A4. In a clinical trial in 12 subjects, dabrafenib decreased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of midazolam, a sensitive CYP3A4 substrate) by 61% and 74%, respectively. Hormonal contraceptives are also metabolized by CYP3A4, therefore, hormonal contraceptive agents may not be reliable in patients taking dabrafenib.(1)

Hormonal Contraceptive Agents/Efavirenz; Nevirapine

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Efavirenz(1) and nevirapine(2,3) may induce the metabolism of hormonal contraceptives via CYP3A4.

CLINICAL EFFECTS: Concurrent administration of efavirenz(1) or nevirapine(2,3) with a hormonal contraceptive agent may result in decreased plasma concentrations and clinical effectiveness of the contraceptive agent.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturers of efavirenz(1) and nevirapine(2) state that hormonal contraceptives should not be used as the sole method of contraception in women taking these agents. A reliable method of barrier contraception must be used in addition to hormonal contraception in women taking efavirenz.(1) Alternative or additional methods of contraception should be considered in women taking nevirapine.(2) Because of the long half-life of efavirenz, women should continue to use a barrier method of contraception in addition to hormonal contraception for 12 weeks after discontinuing efavirenz.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg.(4) Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.

DISCUSSION: In a study in 21 subjects, concurrent efavirenz (600 mg daily for 14 days) and ethinyl estradiol/norgestimate (0.035/0.25 mg for 14 days) had no effect on ethinyl estradiol levels. The maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of norelgestromin decreased by 46%, 64%, and 82%, respectively. The Cmax, AUC, and Cmin of levonorgestrel decreased by 80%, 83%, and 86%, respectively.(1) There have been reports of contraceptive failure in patients with etonogestrel implants who were receiving efavirenz.(1) In a study in 10 subjects taking Ortho-Novum 1/35, nevirapine decreased the AUC of ethinyl estradiol by 20% and the AUC and Cmax of norethindrone by 19% and 16%, respectively.(2) In a study in 16 HIV-positive females, concurrent nevirapine (200 mg daily, Days 2-15; 200 mg twice daily, Days 16-29) and ethinyl estradiol with norethindrone decreased the AUCs of ethinyl estradiol and norethindrone by 29% and 18%, respectively.(3) A study of 118 HIV-positive females compared levonorgestrel pharmacokinetics and safety between the following groups: 1. levonorgestrel 1.5 mg with dolutegravir-based antiretrovirals (ART)(control group), 2. levonorgestrel 1.5 mg with efavirenz-based ART, 3. levonorgestrel 3 mg with efavirenz-based ART, and 4. levonorgestrel 3 mg with rifampin. While both levonorgestrel 3 mg groups had Cmax and AUC(0-8h) similar to the control group, the half life of levonorgestrel was shorter, resulting in an AUC(inf) that was 53% lower in the efavirenz group and 37% lower in the rifampin group than the control group. Tolerability was similar between groups. No pregnancies were reported but it is unknown whether the correction of levonorgestrel levels early in the dosing period is sufficient to maintain overall emergency contraceptive effectiveness.(5)

Hormonal Contraceptive Agents/Encorafenib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Encorafenib may induce the metabolism of hormonal contraceptive agents by CYP3A4.(1)

CLINICAL EFFECTS: Concurrent use of encorafenib and hormonal contraceptive agents may decrease the effectiveness of the hormonal contraceptive agent, which may result in contraceptive failure. Encorafenib may cause birth defects and/or miscarriage if used by pregnant women.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women receiving encorafenib therapy should not rely solely on hormonal contraceptive agents (including oral, implantable, injectable, or transdermal agents) because they may not be effective. Women should be advised to use a highly effective non-hormonal method of contraception during and for 2 weeks after the final dose of encorafenib.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Based on in vitro data, encorafenib is an inducer of CYP3A4 at clinically relevant plasma concentrations.(1) Hormonal contraceptives are also metabolized by CYP3A4, therefore, hormonal contraceptive agents may not be reliable in patients taking encorafenib.(1)

Hormonal Contraceptive Agents/Lumacaftor

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Lumacaftor, a strong inducer of CYP3A4, may induce the metabolism of hormonal contraceptive agents.(1)

CLINICAL EFFECTS: Concurrent use of lumacaftor and hormonal contraceptive agents may decrease the effectiveness of the hormonal contraceptive agent, which may result in contraceptive failure. In addition, menstrual related adverse effects such as such as amenorrhea, dysmenorrhea, menorrhagia and irregular menses are common.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women receiving lumacaftor therapy should not rely solely on hormonal contraceptive agents (including oral, implantable, injectable, or transdermal agents) because they may not be effective. The manufacturer recommends avoiding concomitant use unless the benefit outweighs the risk.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Lumacaftor is a strong inducer of CYP3A4. Hormonal contraceptives are metabolized by CYP3A4, therefore, hormonal contraceptive agents may not be reliable in patients taking lumacaftor.(1) Menstrual irregularities, e.g. amenorrhea, dysmenorrhea, menorrhagia and irregular menses were reported in 27% of lumacaftor patients also taking hormonal contraceptives vs. 3% of female patients not using hormonal contraceptives.(1)

Hormonal Contraceptive Agents/Telaprevir

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Telaprevir may induce the metabolism of hormonal contraceptives by CYP3A4.

CLINICAL EFFECTS: Concurrent use of telaprevir and hormonal contraceptive agents may decrease the effectiveness of the hormonal contraceptive agent, which may result in contraceptive failure. Telaprevir is only indicated for use with ribavirin, a known teratogen.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women receiving telaprevir therapy should not rely on hormonal contraceptive agents (including oral, implantable, injectable, or transdermal agents) because they may not be effective during and for two weeks after completing telaprevir therapy. Two alternative effective methods of contraception (e.g. intrauterine devices and/or barrier methods) should be used during combination treatment with ribavirin and for six months after completing therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: In a study in 24 subjects, concurrent use of telaprevir (750 mg every 8 hours for 21 days) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of ethinyl estradiol (administered as ethinyl estradiol/norethindrone 0.035/0.5 mg daily for 21 days) by 26%, 28%, and 33% respectively. The Cmax, AUC, and Cmin of norethindrone decreased by 15%, 11%, and 6%, respectively. There were no significant effects on telaprevir levels.(1,2)

Hormonal Contraceptives/Artemether

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Artemether may increase the metabolism of hormonal contraceptives.

CLINICAL EFFECTS: Concurrent use of artemether may result in reduced levels and clinical effectiveness of hormonal contraceptives. In the case of contraceptives, breakthrough bleeding and pregnancy may result.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients receiving artemether should be alerted to the possibility of decreased effectiveness of their hormonal contraceptive. It is recommended that alternative or additional non-hormonal contraceptive methods be used during artemether therapy(1) and for 28 days after completing therapy.(2) The patient should be asked to report any spotting or bleeding. For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.

DISCUSSION: Artemether has been shown to weakly induce CYP2C19, CYP2B6, and CYP3A and may reduce the efficacy of hormonal contraceptives.(1)

Hormonal Contraceptives/Belzutifan

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Belzutifan is a weak to moderate CYP3A4 inducer. Coadministration of belzutifan with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1)

CLINICAL EFFECTS: Concurrent use of belzutifan can lead to ineffective hormonal contraceptive and cause fetal harm when administered to a pregnant woman.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Pregnant women and females of reproductive potential should be counseled on the potential risk to the fetus.(1) Advise females of reproductive potential to use effective non-hormonal contraception during treatment with belzutifan and for 1 week after the last dose. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with belzutifan and for 1 week after the last dose.(1) Verify the pregnancy status of females of reproductive potential prior to initiating treatment with belzutifan.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Belzutifan has not been studied with hormonal contraceptives. It can render some hormonal contraceptives ineffective and cause embryo-fetal harm. Women should use non-hormonal contraception during therapy.(1) In an animal reproduction study, oral administration of belzutifan to pregnant rats during the period of organogenesis caused embryo-fetal lethality, reduced fetal body weight, and fetal skeletal malformations at maternal exposures greater than or equal to 0.2 times the human exposure (AUC) at the recommended dose of 120 mg daily.(1)

Hormonal Contraceptives/Bexarotene

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Bexarotene may induce the CYP3A4 mediated metabolism of both estrogen and progestin components of hormonal contraceptives.(1,2)

CLINICAL EFFECTS: Concurrent use of bexarotene may result in reduced levels and clinical effectiveness of hormone containing contraceptives. Breakthrough bleeding and contraceptive failure/pregnancy may result.(1,2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients receiving bexarotene should be alerted to the risk for decreased effectiveness (e.g. contraceptive failure) of their hormonal contraceptive therapy and should be advised to use a reliable non-hormonal contraceptive option.(1) Due to bexarotene being teratogenic in animal studies and may cause fetal harm, the US prescribing information recommends that two reliable forms of contraception be used simultaneously one month before, during, and at least one month after bexarotene therapy. Females of reproductive potential should be advised to avoid becoming pregnant. If treatment with bexarotene is intended in a female with reproductive potential, it is strongly recommended that one of the two reliable forms of contraception should be non-hormonal. The patient should be asked to report any spotting or bleeding.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(3)

DISCUSSION: In a study of bexarotene 400 mg/m2 was administered orally with atorvastatin (another CYP3A4 substrate), the area-under-curve (AUC) of atorvastatin was decreased by 50%.(1) No studies have been conducted looking specifically at hormonal contraceptive use with bexarotene. However, due to the possibility of intended pregnancy the use of non-hormonal contraception needs to be considered.(1)

Hormonal Contraceptives/Cenobamate

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Cenobamate may induce the CYP3A4 mediated metabolism of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of cenobamate may reduce the effectiveness of hormonal contraceptives.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraceptives for contraception. According to the US manufacturer, women should use additional or alternative non-hormonal methods of birth control during cenobamate therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (i.e., a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(2)

DISCUSSION: Cenobamate may induce the CYP3A4 mediated metabolism of hormonal contraceptives. The effectiveness of hormonal contraceptives may be reduced when administered concomitantly with cenobamate. Women should use additional or alternative non-hormonal birth control.(1)

Hormonal Contraceptives/Deferasirox

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Deferasirox may induce the CYP3A4 mediated metabolism of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of deferasirox may reduce the effectiveness of hormonal contraceptives.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use a non-hormonal method of birth control during deferasirox therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (i.e., a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(2)

DISCUSSION: Deferasirox may induce the CYP3A4 mediated metabolism of hormonal contraceptives. Deferasirox may decrease the effectiveness of hormonal contraceptives, including oral contraceptives, patches, implants, and/or IUDs. Women should use a non-hormonal method of birth control during deferasirox therapy.(1)

Hormonal Contraceptives/Elagolix

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Based on the mechanism of action of elagolix, estrogen containing contraceptives are expected to reduce the efficacy of elagolix. The effect of progestin-only contraceptives on elagolix is unknown.(1) Elagolix is a weak to moderate inducer of CYP3A4 and may increase the metabolism of progestins. The mechanism of elagolix's interaction with estrogens is unknown.(1)

CLINICAL EFFECTS: Concurrent use of hormonal contraceptives may reduce the effectiveness of elagolix.(1) Elagolix 200 mg twice daily may increase the levels and toxicity of estrogens, including thromboembolic disorders and vascular events, while decreasing the levels and efficacy of progestin-containing hormonal contraceptives. Elagolix may cause birth defects and/or miscarriage if used by pregnant women.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive potential should use effective non-hormonal methods of contraception during elagolix therapy and for 28 days after discontinuing elagolix. Women of reproductive age should be counseled not to use hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception.(1)

DISCUSSION: Hormonal contraceptives may decrease the effectiveness of elagolix. Women should use a non-hormonal method of birth control during elagolix therapy.(1) Coadministration of elagolix 200 mg twice daily for 14 days with ethinyl estradiol 20 mcg-levonorgestrel 0.1 mg resulted in a 2.2-fold increase in ethinyl estradiol exposure and a 27% decrease in levonorgestrel exposure.(1) Coadministration of elagolix 150 mg daily did not affect exposure to norethindrone 0.35 mg once daily nor to ethinyl estradiol 35 mcg-triphasic norgestimate 0.18/0.215/0.25 mg once daily.(1)

Hormonal Contraceptives/Elvitegravir-Cobicistat

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: The exact mechanism is unknown.

CLINICAL EFFECTS: Concurrent administration may result in increased effects from the progestin (insulin resistance, dyslipidemia, acne, and venous thrombosis) and decreased effects of the estrogen component.(1,2) Concurrent use of cobicistat-containing products may result in elevated levels of and adverse effects from drospirenone, including hyperkalemia.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of cobicistat-elvitegravir-emtricitabine-tenofovir recommends the use of non-hormonal methods of contraception.(1) The manufacturer of cobicistat-elvitegravir-emtricitabine-tenofovir alafenamide recommends clinical monitoring due to the potential for hyperkalemia when administered concurrently with drospirenone-ethinyl estradiol.(2)

DISCUSSION: Concurrent administration of cobicistat-elvitegravir-emtricitabine-tenofovir increased Cmax, AUC, and minimum concentration (Cmin) of norgestimate by 2.08-fold, 2.26-fold, and 2.67-fold, respectively. The Cmax, AUC, and Cmin of ethinyl estradiol decreased by 6%, 25%, and 44%, respectively.(1) Drospirenone has anti-mineralocorticoid activity comparable to a 25mg dose of spironolactone.

Hormonal Contraceptives/Enasidenib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Enasidenib may increase or decrease the metabolism of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of enasidenib may increase side effect from or reduce the effectiveness of hormonal contraceptives. Enasidenib may cause birth defects if used by pregnant women.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use a back-up method of birth control during enasidenib therapy. Women of reproductive potential should use effective non-hormonal methods of contraception during enasidenib therapy and for at least 2 months after the final dose.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Enasidenib may increase or decrease metabolism of hormonal contraceptives. Enasidenib may increase or decrease the effectiveness of hormonal contraceptives, including oral contraceptives, patches, implants, and/or IUDs. Women should use a back-up method of birth control during enasidenib therapy and for at least 1 month after the final dose.(1)

Hormonal Contraceptives/Ixazomib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Ixazomib does not interact with hormonal contraceptives, but the dexamethasone used with ixazomib is a weak to moderate CYP3A4 inducer and may increase the CYP3A4 mediated metabolism of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of ixazomib with dexamethasone may reduce the effectiveness of hormonal contraceptives.(1) Ixazomib may cause birth defects and/or miscarriage if used by pregnant women.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use an effective non-hormonal back-up method of birth control during and for 90 days after ixazomib-dexamethasone therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Ixazomib-dexamethasone has not been studied with hormonal contraceptives. Dexamethasone may decrease the effectiveness of hormonal contraceptives, including oral contraceptives, patches, implants, and/or IUDs. Women should use a back-up method of birth control during ixazomib-dexamethasone therapy.(1)

Hormonal Contraceptives/Lesinurad

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Lesinurad may induce the CYP3A4 mediated metabolism of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of lesinurad may reduce the effectiveness of hormonal contraceptives.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use a back-up method of birth control during lesinurad therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Lesinurad may decrease the effectiveness of hormonal contraceptives, including oral contraceptives, patches, implants, and/or IUDs. Women should use a back-up method of birth control during lesinurad therapy.(1)

Hormonal Contraceptives/Lorlatinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Lorlatinib may induce the CYP3A4 mediated metabolism of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of lorlatinib may reduce the effectiveness of hormonal contraceptives.(1) Lorlatinib may cause birth defects and/or miscarriage if used by pregnant women.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use a back-up method of birth control during lorlatinib therapy and for at least 6 months after the final dose. Women of reproductive potential should use effective non-hormonal methods of contraception during lorlatinib therapy and for at least 6 months after the final dose.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Lorlatinib may induce the CYP3A4 mediated metabolism of hormonal contraceptives. Lorlatinib may decrease the effectiveness of hormonal contraceptives, including oral contraceptives, patches, implants, and/or IUDs. Women should use a back-up method of birth control during lorlatinib therapy and for at least 6 months after the final dose.(1)

Hormonal Contraceptives/Mifepristone

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Mifepristone is a progesterone-receptor antagonist, which will interfere mechanism of action of hormonal contraceptives (including oral, implantable, injectable, or transdermal agents).(1)

CLINICAL EFFECTS: Concurrent use of mifepristone may decrease the effectiveness of hormonal contraceptives. Mifepristone will result in the loss of any pregnancy that results from decreased hormonal contraceptive efficacy.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Females of reproductive age maintained on mifepristone for hyperglycemia secondary to hypercortisolism should use a non-hormonal form of contraception during and for 1 month after mifepristone therapy unless they have been surgically sterilized.(1)

DISCUSSION: Mifepristone is a progesterone-receptor antagonist, which will interfere mechanism of action of hormonal contraceptives. Mifepristone will result in the loss of any pregnancy that results from decreased hormonal contraceptive efficacy. Therefore, females of reproductive age maintained on mifepristone for hyperglycemia secondary to hypercortisolism should use a non-hormonal form of contraception during and for 1 month after mifepristone therapy unless they have been surgically sterilized.(1)

Hormonal Contraceptives/Mitapivat

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Mitapivat is a moderate CYP3A4 inducer. Coadministration of mitapivat with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1)

CLINICAL EFFECTS: Concurrent use of mitapivat can lead to ineffective hormonal contraceptive and cause unintended pregnancy.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraceptives (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Pregnant women and females of reproductive potential should be counseled on the potential risk to the fetus.(1) Advise females of reproductive potential to use effective non-hormonal contraception during treatment with mitapivat.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Mitapivat is a moderate CYP3A4 inducer. Mitapivat has not been studied with hormonal contraceptives. It can render some hormonal contraceptives ineffective and may cause unintended pregnancy. Women should use non-hormonal contraception during therapy.(1) In an animal reproduction study, oral administration of mitapivat to pregnant rats and rabbits during the period of organogenesis was not teratogenic at doses up to 13 and 3 times the maximum recommended ose.(1)

Hormonal Contraceptives/Mycophenolate

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: The exact mechanism is unknown.

CLINICAL EFFECTS: Concurrent use of mycophenolate may result in decreased levels and effectiveness of hormonal contraceptives. The use of mycophenolate in pregnancy has been associated with an increased risk for first trimester pregnancy loss and and congenital malformations.(1,2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients should be informed that mycophenolate may reduce the effectiveness of hormonal contraceptives and that the use of mycophenolate in pregnancy has been associated with an increased risk for first trimester pregnancy loss and congenital malformations.(1,2) Female patients of childbearing potential should use two forms of contraception four weeks prior to initiating mycophenolate, during therapy, and for six weeks after completing mycophenolate therapy.(1,2)

DISCUSSION: In a study in 18 female patients, concurrent mycophenolate mofetil (1 gram twice daily) and oral contraceptives containing ethinyl estradiol (0.02 to 0.04 mg) with levonorgestrel (0.05 mg to 0.20 mg), desogestrel (0.15 mg), or gestodene (0.05 mg to 0.10 mg) decreased the area-under-curve (AUC) of levonorgestrel by 15%. There was large inter-patient variability in the data, especially for ethinyl estradiol. Mean serum levels of LH, FSH, and progesterone were not significantly affected. (1)

Hormonal Contraceptives/Pegaspargase

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: An indirect interaction may occur due to pegaspargase hepatotoxicity resulting in decreased hepatic clearance of hormonal contraceptives.(1,2) Both medicines may also cause thromboembolic events.

CLINICAL EFFECTS: Concurrent use of pegaspargase may result in increased levels and effects of hormonal contraceptives and increase the risk of venous thromboembolism.(3)

PREDISPOSING FACTORS: Patients with risk factors for thrombosis include those with advanced age, obesity (BMI >30), smoking, prolonged immobilization, heart failure, hypercoagulable states, history of venous thromboembolism, malignancy, and major surgery.

PATIENT MANAGEMENT: The Australian and UK manufacturers of pegaspargase state that hormonal contraceptives are not considered to be sufficiently safe in patients on pegaspargase. Concurrent use of hormonal contraceptives and pegaspargase is not recommended.(1,2) The US manufacturer of pegaspargase states that females of reproductive potential should be counseled to use an effective non-hormonal contraceptive method during and for 3 months after therapy with pegaspargase.(4) The UK manufacturer of pegaspargase recommends using non-oral contraceptives during and for 6 months after therapy with pegaspargase.(2)

DISCUSSION: Hepatotoxicity caused by pegaspargase may result in increased exposure to hormonal contraceptives and increase the risk of thromboembolism. Concurrent use of hormonal contraceptives is not recommended.(1-4)

Hormonal Contraceptives/Pitolisant

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Pitolisant may induce the CYP3A4 mediated metabolism of hormonal contraceptives.(1,2)

CLINICAL EFFECTS: Concurrent use of pitolisant may reduce the effectiveness of hormonal contraceptives.(1,2) Pitolisant may cause birth defects and/or miscarriage if used by pregnant women.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use a back-up method of birth control during pitolisant therapy and for at least 21 days after the final dose. Women of reproductive potential should use effective non-hormonal methods of contraception during pitolisant therapy and for at least 21 days after the final dose.(1,2) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(3)

DISCUSSION: Pitolisant may induce the CYP3A4 mediated metabolism of hormonal contraceptives. Pitolisant may decrease the effectiveness of hormonal contraceptives, including oral contraceptives, patches, implants, and/or IUDs. Women should use a back-up method of birth control during pitolisant therapy and for at least 21 days after the final dose.(1,2)

Hormonal Contraceptives/Repotrectinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Repotrectinib may induce the CYP3A4-mediated metabolism of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of repotrectinib may reduce the blood concentrations and effectiveness of hormonal contraceptives. Repotrectinib may cause fetal harm when administered to pregnant women.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled to avoid hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) due to the risk of contraceptive failure. Women should use an effective non-hormonal method of contraception during and for 2 months after repotrectinib therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (i.e., a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: Repotrectinib is a moderate CYP3A4 inducer. In a study, repotrectinib decreased the area-under-curve (AUC) and maximum concentration (Cmax) of midazolam (a sensitive CYP3A4 substrate) by 69% and 48%, respectively. It may also decrease estrogen or progestin concentrations and reduce the effectiveness of hormonal contraceptives. Repotrectinib may cause fetal harm when administered to pregnant women.(1)

Hormonal Contraceptives/Rifamycins

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Rifamycins (rifampin, rifabutin and rifapentine) induce the CYP3A4 mediated metabolism of both estrogen and progestin components of hormonal contraceptives.

CLINICAL EFFECTS: Concurrent use of rifampin, rifabutin, or rifapentine may result in reduced levels and clinical effectiveness of hormone containing contraceptives. Breakthrough bleeding and contraceptive failure/pregnancy may result. Effects may be seen for several weeks after discontinuation of the rifamycin.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients receiving rifamycins should be alerted to the risk for decreased effectiveness(e.g. contraceptive failure) of their hormonal contraceptive therapy. It is recommended that alternative or additional contraceptive methods be used during and for several weeks after rifamycin therapy. If a combined oral contraceptive is used, the preparation should contain at least 30 mcg of ethinyl estradiol should be used. The patient should be asked to report any spotting or bleeding. For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.

DISCUSSION: In an open-label, randomized crossover study, 22 healthy females received oral contraceptives for 21 days, then were randomized to receive rifampin or rifabutin (300 mg/d for 10 days). Rifampin and rifabutin decreased the area-under-curve (AUC) of ethinyl estradiol by 64% and 35%, respectively, and maximum concentration (Cmax) by 42% and 20%, respectively. Rifampin and rifabutin decreased the AUC of norethindrone by 60% and 20%, respectively. Incidences of spotting were much greater in the rifampin co-administration group. In a study, a single dose of oral contraceptive (ethinyl estradiol 50 mcg and norethindrone acetate 1 mg) was administered to 7 female patients with tuberculosis, both during TB treatment and one month after stopping rifampin (450-600 mg/d). Upon cessation of rifampin therapy, the AUC for ethinyl estradiol significantly increased by 70%, and terminal plasma half-life more than doubled. A similar study design analyzed the pharmacokinetics of norethisterone (1 mg) in 8 women receiving rifampin (450-600 mg/d). Upon termination of TB treatment, it was found that rifampin reduced the AUC of a single dose of norethisterone (1 mg) by approximately 40%, with a half-life reduction of 50%. In a study, male volunteers received 50 mcg iv of ethinyl estradiol, followed by rifampin (600 mg for 6 days). Ethinyl estradiol half-life decreased by approximately 55%. The upward titration of ethinyl estradiol to 100 mcg resulted in a more than 2-fold increase in ethinyl estradiol metabolism caused by rifampicin treatment. An analytical trial evaluated liver biopsies from four patients treated with rifampin 600 mg for a period of 6-10 days. Hepatic microsomes from the biopsies were incubated with hormone substrates, including oestradiol and ethinyl estradiol. Rifampin resulted in a fourfold increase in hydroxylation. Not only did rifampin increase the rate of hydroxylation through enzyme induction, it also caused an increase in cytochrome P-450. There are reports of breakthrough bleeding and unintended pregnancy during concurrent use. A study of 118 HIV-positive females compared levonorgestrel pharmacokinetics and safety between the following groups: 1. levonorgestrel 1.5 mg with dolutegravir-based antiretrovirals (ART)(control group), 2. levonorgestrel 1.5 mg with efavirenz-based ART, 3. levonorgestrel 3 mg with efavirenz-based ART, and 4. levonorgestrel 3 mg with rifampin. While both levonorgestrel 3 mg groups had Cmax and AUC(0-8h) similar to the control group, the half life of levonorgestrel was shorter, resulting in an AUC(inf) that was 53% lower in the efavirenz group and 37% lower in the rifampin group than the control group. Tolerability was similar between groups. No pregnancies were reported but it is unknown whether the correction of levonorgestrel levels early in the dosing period is sufficient to maintain overall emergency contraceptive effectiveness.(25)

Hormonal Contraceptives/Selected Anticonvulsants

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Carbamazepine is a strong inducer of CYP3A4; oxcarbazepine and rufinamide are weak inducers of CYP3A4.(1)

CLINICAL EFFECTS: Concurrent use with carbamazepine, oxcarbazepine or rufinamide may result in decreased contraceptive levels, which may result in menstrual abnormalities or unintended pregnancy.

PREDISPOSING FACTORS: Intermittent compliance with oral contraceptives.

PATIENT MANAGEMENT: To avoid pregnancy, additional or alternative means of non-hormonal contraception should be utilized. If larger doses of hormonal contraceptives are utilized, titrating the dose against a response such as lack of spotting or breakthrough bleeding may not guarantee contraceptive efficacy. In women who wish to continue oral contraceptives with the addition of a second form of contraception, emphasize the importance of not missing doses of the oral contraceptive. For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.

DISCUSSION: In a study of four epileptic patients receiving an oral contraceptive containing ethinyl estradiol 50 mcg plus levonorgestrel 250 mcg carbamazepine reduced the area-under-curve (AUC) for ethinyl estradiol by 42% and for levonorgestrel by 40%. Pregnancy has been reported. Pregnancy has been reported in a woman receiving low-dose oral contraceptives six weeks after initiation of treatment with carbamazepine. In a randomized, open label study, concurrent administration of carbamazepine (600 mg daily) and Ortho Novum 1/35 (ethinyl estradiol, norethindrone) decreased the AUC of ethinyl estradiol and norethindrone by 42% and 58%, respectively. The apparent oral clearance of ethinyl estradiol and norethindrone increased by 127% and 69%, respectively. Concurrent use of rufinamide (800 mg twice daily) and ethinyl estradiol / norethindrone (35 mcg/1 mg) for 14 days decreased the AUC of ethinyl estradiol and norethindrone by 22% and 14%, respectively. The maximum concentration (Cmax) of ethinyl estradiol and norethindrone decreased by 31% and 18%, respectively. Double-blind, randomized, crossover study with 24 women (only 20 analyzed) given 20 micrograms ethinyl estradiol and 100 micrograms levonorgestrel and either carbamazepine 600 mg or a matched placebo for 4 months. Ethinyl estradiol and levonorgestrel levels were measured and mean AUC was significantly lower in those taking carbamazepine. Cmax of ethinyl estradiol was also significantly decreased. Additionally more cases of breakthrough bleeding and ovulation occurred with concurrent use of the carbamazepine. In a case report, a patient with an etonogestrel implant became pregnant while taking carbamazepine for epilepsy. Coadministration of immediate-release oxcarbazepine decreased mean ethinyl estradiol AUC levels in two different studies by 48% and 52%, respectively. Additionally, mean AUC of levonorgestrel was decreased in two different studies by 32% and 52%, respectively.

Hormonal Contraceptives/Selected Strong & Mod Cyp3a4 Inducer

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Strong and moderate CYP3A4 inducers may increase the CYP3A4-mediated metabolism of hormonal contraceptives.(1-2)

CLINICAL EFFECTS: Concurrent use of strong or moderate CYP3A4 inducers may reduce the effectiveness of hormonal contraceptives.(1-2) Apalutamide, enzalutamide, ivosidenib, and mitotane may cause birth defects and/or miscarriage if used by pregnant women.

PREDISPOSING FACTORS: Induction effects may be more likely with regular use of the inducer for longer than 1-2 weeks.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use a back-up method of birth control during therapy with a CYP3A4 inducer. Women of reproductive potential should use effective non-hormonal methods of contraception during therapy with a CYP3A4 inducer. Continuation of an effective non-hormonal contraceptive after discontinuation of the CYP3A4 inducer is also advised for the period of time indicated below.(1-3) There is no specific recommendation for contraception in women on apalutamide or enzalutamide. Male patients with female partners of reproductive age are advised to continue effective contraception for 3 months after discontinuation of apalutamide or enzalutamide.(4,5) For patients taking fexinidazole: The manufacturer of fexinidazole recommends alternative contraceptive that is not affected by enzyme inducers or additional nonhormonal contraception during and for at least 5 days after treatment with fexinidazole.() For patients taking mitapivat: The manufacturer of mitotane recommends continuing effective contraception after discontinuation of mitotane for as long as mitotane plasma levels are detectable. Mitotane half life ranges from 18 to 159 days (median 53 days).(3) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(6)

DISCUSSION: Strong and moderate CYP3A4 inducers may increase the CYP3A4-mediated metabolism of hormonal contraceptives and decrease the effectiveness of hormonal contraceptives, including oral contraceptives, patches, implants, and/or IUDs. Women should use a back-up method of birth control during and after CYP3A4 inducer therapy.(1-3) An in vivo mechanism static model predicted strong interactions between ulipristal combined with enzalutamide or mitotane. Enzalutamide was predicted to lower ulipristal area-under-curve (AUC) by 85%, and mitotane was predicted to lower ulipristal AUC by 93%.(2) Strong and moderate CYP3A4 inducers linked include: apalutamide, enzalutamide, fexinidazole, ivosidenib, mitotane, nafcillin, sotorasib, telotristat, and thioridazine.(7,8)

Hormonal Contraceptives/St. John's Wort

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: St. John's wort may induce the metabolism of hormonal-containing contraceptives by CYP3A4.(1-8)

CLINICAL EFFECTS: The concurrent administration of St. John's wort may result in reduced levels and clinical effectiveness of hormonal-containing contraceptives.(1-8)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women taking hormonal contraception should be alerted to the possibility of decreased effects of their hormonal-containing contraceptive if they take St. John's wort. Consider monitoring for menstrual irregularities and pregnancy during concurrent therapy. The dosage of the contraceptive may need to be adjusted if St. John's wort is added to or discontinued from concurrent therapy, or another form of birth control may need to be considered. St. John's wort may need to be discontinued. For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.

DISCUSSION: The FDA and CDC recommend that patients taking estrogen-containing oral contraceptives be alerted to the possibility of a drug interaction resulting in decreased levels and/or effects of the oral contraceptive.(1,2) In a study in 12 healthy women taking ethinyl estradiol-norethindrone, administration of St. John's wort (300 mg 3 times daily) increased the oral clearance of norethindrone and decreased the half-life of ethinyloestradiol. Serum concentrations of follicle-stimulating hormone, luteinizing hormone, and progesterone were not significantly affected by St. John's wort. Breakthrough bleeding occurred in 2 of 12 subjects in the control phase and 7 of 12 women during the St. John's wort phase.(3) In a study in 17 healthy women, subjects receiving ethinyloestradiol-desogestrel alone, with 300 mg St. John's wort twice daily, and with 300 mg St. John's wort 3 times daily. There was no significant changes in follicle maturation, serum estrogen, or serum progesterone concentrations during St. John's wort. During the control phase, 6 women reported breakthrough bleeding, compared with 13 women while taking St. John's wort twice daily and 15 women while taking St. John's wort 3 times daily. There were no changes in the area-under-curve (AUC) or maximum concentration (Cmax) of ethinyloestradiol. However, the AUC and Cmax of 3-ketodesogestrel decreased by 43.9% and by 17.8%, respectively during twice daily St. John's wort and by 41.7% and by 22.8%, respectively during 3 times daily St. John's wort.(4) In a study in 16 healthy women, concurrent St. John's wort (300 mg three times daily) decreased the exposure from Loestrin 1/20 (estradiol with norethindrone) by 13% to 15%. Breakthrough bleeding and evidence of follicle growth and probable ovulation increased during concurrent St. John's wort.(6) Unplanned pregnancies have been reported during concurrent St. John's wort and hormonal contraception.(4,7) In a study in 15 healthy women, concurrent St. John's wort and Loestrin 1/20 did not affect androgen levels when compared to Loestrin 1/20 alone, suggesting that concurrent therapy would not impair treatment of acne or hirsutism.(8)

Hormonal Contraceptives/Sugammadex

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Sugammadex may bind to hormonal contraceptives.(1,2)

CLINICAL EFFECTS: Use of sugammadex may result in decreased levels of hormonal contraceptive similar to those seen with a missed dose of an oral contraceptive, which may result in decreased hormonal contraceptive effectiveness.(1,2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of sugammadex recommends that all patients using hormonal contraceptives use an additional non-hormonal contraceptive method for 7 days following the administration of sugammadex.(1) The UK manufacturer of sugammadex recommends that patients taking oral hormonal contraceptives should be instructed to follow the missed dose instructions for their oral hormonal contraceptive on the day they receive sugammadex. Patients taking non-oral hormonal contraceptives should use an additional non-hormonal contraceptive method for 7 days following the administration of sugammadex and should refer to the advice in the package leaflet of their non-oral hormonal contraceptive.(2)

DISCUSSION: Use of sugammadex may result in decreased levels of hormonal contraceptive similar to those seen with a missed dose of an oral contraceptive, which may result in decreased hormonal contraceptive effectiveness.(1,2)

Hormonal Contraceptives/Tazemetostat

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Tazemetostat is a weak CYP3A4 inducer and may increase the CYP3A4-mediated metabolism of both estrogen and progestin components of hormonal contraceptives.(1)

CLINICAL EFFECTS: Coadministration of tazemetostat with hormonal contraceptives can result in decreased concentrations and reduced efficacy.(1) Breakthrough bleeding and contraceptive failure/pregnancy may result. Tazemetostat may cause fetal harm if administered to pregnant women.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of tazemetostat recommends that female patients of reproductive potential use effective non-hormonal contraception during treatment with tazemetostat and for 6 months after the final dose.(1) Patients should be alerted to the risk for decreased effectiveness(e.g. contraceptive failure) of their hormonal contraceptive therapy. For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (i.e., a copper IUD).(2)

DISCUSSION: Coadministration of tazemetostat 800 mg twice daily with oral midazolam, a sensitive CYP3A4 substrate, in patients decreased midazolam area-under-curve (AUC) by 40% and maximum concentration (Cmax) by 21%.(1)

Hormonal Contraceptives/Tovorafenib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Tovorafenib may induce the CYP3A4-mediated metabolism of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of tovorafenib may reduce the blood concentrations and effectiveness of hormonal contraceptives. Tovorafenib may cause fetal harm when administered to pregnant women.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled to avoid hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) due to the risk of contraceptive failure. Women should use an effective non-hormonal method of contraception during and for 28 days after tovorafenib therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (i.e., a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: A pharmacokinetic model predicted tovorafenib to decrease midazolam Cmax and AUC by at least 20%. Tovorafenib may also decrease estrogen or progestin concentrations and reduce the effectiveness of hormonal contraceptives and/or an increase in breakthrough bleeding. Tovorafenib may cause fetal harm when administered to pregnant women.(1)

Hormonal Contraceptives/Zanubrutinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Zanubrutinib is a weak CYP3A4 inducer. Coadministration of zanubrutinib with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding due to decreased hormonal concentrations.(1,2)

CLINICAL EFFECTS: Concurrent use of zanubrutinib may reduce the effectiveness of hormonal contraceptives.(1,2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled to use highly effective contraception due to the risk of fetal harm with zanubrutinib. Women of reproductive age should not rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) due to the risk of contraceptive failure. Women who use hormonal methods of birth control must add a barrier method.(1) Advise females of reproductive potential to use effective non-hormonal contraception (e.g., non-hormonal intrauterine system) or additional non-hormonal contraceptive (e.g., condoms) during treatment with zanubrutinib and for 7 days after the last dose.(1,2) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if she does become pregnant.(3)

DISCUSSION: Zanubrutinib is a weak CYP3A4 inducer.(1,2) Coadministration of zanubrutinib with midazolam (a CYP3A substrate) decreased the concentration maximum (Cmax) and area-under-curve (AUC) of midazolam by 30% and 47%, respectively.(1,2)

Progestin-Containing Contraceptives/Ulipristal

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Ulipristal is a progesterone receptor modulator and binds to the progesterone receptor with high affinity.(1)(2)

CLINICAL EFFECTS: Concurrent use of ulipristal may make hormonal contraception (including combined hormonal products, progestin-only products, and levonorgestrel emergency contraception) ineffective.(1,2) These agents may also make ulipristal ineffective.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US and UK manufacturers of ulipristal recommends that patients who have received ulipristal use a reliable barrier method of contraception for subsequent acts of intercourse until the next menstrual cycle begins.(1)(2) The US manufacturer of ulipristal states that if a woman wishes to start or resume hormonal contraception after taking ulipristal, she should do so no sooner than 5 days afterwards. The UK manufacturer of ulipristal states that concurrent use with levonorgestrel emergency contraception is not recommended.(1)

DISCUSSION: Ulipristal is a progesterone receptor modulator and binds to the progesterone receptor with high affinity, thus it may interfere with the efficacy of hormonal contraception (including combined hormonal products, progestin-only products, and levonorgestrel emergency contraception) and progestin products.(1-2) These products may also make ulipristal ineffective.

Selected Hormonal Contraceptives/Suzetrigine

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Suzetrigine may induce the metabolism of hormonal contraceptives containing progestins other than levonorgestrel and norethindrone.(1)

CLINICAL EFFECTS: Concurrent use of suzetrigine and hormonal contraceptives containing progestins other than levonorgestrel or norethindrone may result in decreased levels and effectiveness of the contraceptive.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of suzetrigine advises that suzetrigine-treated patients using hormonal contraceptives containing progestins other than levonorgestrel and norethindrone should either: - Use additional non-hormonal contraceptives, - Use alternative contraceptives such as a combined oral contraceptive containing ethinyl estradiol as the estrogen and levonorgestrel or norethindrone as the progestin, or - Use an intrauterine system The alternative birth control method should be used during treatment with suzetrigine and for 28 days after discontinuation of suzetrigine.(1)

DISCUSSION: Suzetrigine did not result in clinically significant changes in the pharmacokinetics of ethinyl estradiol and levonorgestrel when used concomitantly with an oral contraceptive containing ethinyl estradiol and levonorgestrel.(1) Suzetrigine administered 50 mg every 12 hours at steady state decreased the area-under-curve (AUC) of midazolam (a CYP3A4 substrate) by 48% and maximum concentration (Cmax) by 37%.(1)

Steroidal Contraceptives/Aprepitant; Fosaprepitant

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Aprepitant and fosaprepitant may induce the CYP3A4 mediated metabolism of hormonal contraceptives.(1,2)

CLINICAL EFFECTS: The effectiveness of hormonal contraceptives may be reduced during and for 28 days following aprepitant and fosaprepitant use.(1,2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients taking hormonal contraceptives should be instructed to use alternative or back-up methods of contraception while using aprepitant or fosaprepitant and for 1 month after the last dose of aprepitant or fosaprepitant.(1,2) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.

DISCUSSION: The concurrent use of aprepitant (100 mg daily for 14 days) with an oral contraceptive (ethinyl estradiol, 35 mcg and norethindrone, 1 mg) decreased the area-under-curve (AUC) of ethinyl estradiol and norethindrone by 43% and 8%, respectively.(1) In another study, an oral contraceptive (ethinyl estradiol and norethindrone, dosages not stated) was administered on Days 1 through 21. Subjects also received aprepitant (125 mg Day 8, 80 mg daily Days 9 and 10), ondansetron (32 mg Day 8), dexamethasone (12 mg Day 8, 8 mg daily Days 9 through 11). The AUC of ethinyl estradiol decreased by 19% on Day 10 and by as much as 64% on Days 9 through 21. There was no effect on the AUC of norethindrone on Day 10, but there was as much as a 60% decrease in norethindrone minimum concentration (Cmin) during Days 9 through 21.(1) In another study, an oral contraceptive (ethinyl estradiol and norgestimate, dosages not stated) was administered on Days 1 through 21. Subjects also received aprepitant (40 mg Day 8). The AUC of ethinyl estradiol decreased by 4% and 29% on Days 8 and 12, respectively. The AUC of norelgestromin (norgestimate is converted to norelgestromin) increased by 18% on Day 8 and decreased by 10% on Day 12. Trough concentrations of ethinyl estradiol and norelgestromin on Days 8 through 21 were generally lower following aprepitant.(1)

Steroidal Contraceptives/Armodafinil; Modafinil

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Modafinil may induce the CYP3A4 mediated metabolism of the steroidal contraceptive.(1-3) Armodafinil is the R-enantiomer of modafinil.(4)

CLINICAL EFFECTS: Armodafinil(4) or modafinil(1-3) may result in decreased levels of steroidal contraceptives and possibly decreased effectiveness of the contraceptive agent during and one(1,4) to two(2-3) months following armodafinil or modafinil therapy.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The United Kingdom manufacturer of modafinil states that when oral contraceptives are used concurrently with modafinil, a product containing 50 mcg or more of ethinyl estradiol should be used. Adequate contraception requires continuation of the oral contraceptive two months after the discontinuation of modafinil.(2) The Australian manufacturer of modafinil states that alternative or concomitant methods of contraception are recommended for patients on modafinil until 2 months after discontinuation of modafinil.(3) The United States manufacturer of armodafinil(4) and modafinil(1) states that because the effectiveness of steroidal contraceptives may be decreased during concurrent therapy, alternative or concomitant methods of contraception are recommended during therapy and for one month following discontinuation of armodafinil or modafinil. For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(5)

DISCUSSION: Modafinil is contraindicated during pregnancy and may induce the metabolism of oral,(2) depot, and implantable(1) contraceptives, thus decreasing their effectiveness. A placebo-controlled, single-blind study in 41 females evaluated the effect of modafinil on the pharmacokinetics of ethinyl estradiol. The study subjects were controlled on long-term oral contraceptive treatment (0.035 mg ethinyl estradiol) and norgestimate (0.180-0.250 mg). Pharmacokinetic profiles were obtained for ethinyl estradiol on the day before initiation and on the last day of modafinil (200 mg for 7 days, then 400 mg for 21 days) or placebo (28 days). A small, but significant decrease in the ethinyl estradiol area-under-curve (AUC) by 18%, and maximum concentration (Cmax) by 11% were reported.(6)

Moderate Interaction: Assess the risk to the patient and take action as needed.

Hormonal Contraceptives/Asunaprevir

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Asunaprevir is a weak CYP3A4 inducer and may increase the CYP3A4-mediated metabolism of both estrogen and progestin components of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of asunaprevir may result in reduced levels and clinical effectiveness of hormone containing contraceptives.(1) Breakthrough bleeding and contraceptive failure/pregnancy may result. Effects may be seen for several weeks after discontinuation of asunaprevir.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of asunaprevir recommends using a high-dose oral contraceptive containing at least 30 mcg ethinyl estradiol with norethindrone when use concurrently with asunaprevir.(1) Patients should be alerted to the risk for decreased effectiveness(e.g. contraceptive failure) of their hormonal contraceptive therapy. For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: A study of 17 subjects found that asunaprevir 600 mg twice daily decreased the maximum concentration (Cmax) and area-under-curve (AUC) of ethinyl estradiol 35 mcg daily by 25% and 28%, respectively, and of norgestromin by 29% and 34%, respectively.(3) Another study of 36 subjects found that asunaprevir 100 mg twice daily did not significantly affect the kinetics of high-dose contraceptives consisting of ethinyl estradiol 30 mcg daily and norethindrone 1.5 mg daily.(3)

Hormonal Contraceptives/Cannabidiol

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Cannabidiol (CBD) may induce the CYP3A4-mediated metabolism of hormonal contraceptives.(1)

CLINICAL EFFECTS: Concurrent use of CBD may reduce the effectiveness of hormonal contraceptives.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use an effective non-hormonal method of contraception or a back-up method of birth control during CBD therapy.(1) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: An in vitro, CYP induction study showed that CBD may increase expression of CYP3A4. The effectiveness of hormonal contraceptives, including oral contraceptives, patches, implants, and/or IUDs may be decreased. Women should use a back-up method of birth control during CBD or THC therapy.(1)

Hormonal Contraceptives/Meropenem-Vaborbactam

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Meropenem-vaborbactam may induce the CYP3A4-mediated metabolism of hormonal contraceptives.(1,2)

CLINICAL EFFECTS: Concurrent use of meropenem-vaborbactam may reduce the blood concentrations and effectiveness of hormonal contraceptives.(1,2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use an effective non-hormonal method of contraception or an additional method of birth control during and for 28 days after meropenem-vaborbactam therapy.(1,2) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (i.e., a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(2)

DISCUSSION: There have been no studies evaluating the potential of meropenem-vaborbactam to interact with other drugs. In vitro data suggest that both meropenem and vaborbactam are weak CYP3A4 inducers.(1,2)

Hormonal Contraceptives/Tecovirimat

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Tecovirimat may induce the CYP3A4-mediated metabolism of hormonal contraceptives.(1,2)

CLINICAL EFFECTS: Concurrent use of tecovirimat may reduce the effectiveness of hormonal contraceptives.(1,2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Women of reproductive age should be counseled not to rely on hormonal contraception (including oral contraceptives, patches, implants, and/or IUDs) for contraception. Women should use an effective non-hormonal method of contraception or a back-up method of birth control during and for 28 days after tecovirimat therapy.(1,2) For emergency contraception, the UK's Medicines & Healthcare Products Regulatory Agency (MHRA) recommends that women who have used a CYP3A4 inducer in the previous 4 weeks should consider a non-hormonal emergency contraceptive (ie a copper IUD). If a non-hormonal emergency contraceptive is not an option, double the usual dose of levonorgestrel from 1.5 to 3 mg. Advise the patient to have a pregnancy test to exclude pregnancy after use and to seek medical advice if they do become pregnant.(3)

DISCUSSION: In a pharmacokinetic study, tecovirimat decreased the concentration maximum (Cmax) and area-under-curve (AUC) of midazolam (a CYP3A4 substrate) by 39% and 32%, respectively. The effectiveness of hormonal contraceptives, including oral contraceptives, patches, implants, and/or IUDs may be decreased. Women should use a back-up method of birth control during and for 28 days after tecovirimat therapy.(1)

Medroxyprogesterone; Megestrol/Coumarin Anticoagulants

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: The mechanism of this interaction is unknown but may involve inhibition of anticoagulant metabolism by medroxyprogesterone and megestrol.(1,2)

CLINICAL EFFECTS: The concurrent use of medroxyprogesterone or megestrol and coumarin anticoagulants may increase international normalized ratio (INR) and result in an increased risk for bleeding.(1,2)

PREDISPOSING FACTORS: The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). Pharmacogenomic information: patients with a CYP2C9 intermediate metabolizer genotype, and/or 1-2 copies of a reduced function VKORC1 gene are expected to be more susceptible to this interaction. Although patients with a pre-existing CYP2C9 poor metabolizer genotype are expected to be less susceptible to effects from this drug combination, their reduced function genotypes (e.g. CYP2C9 *1/*3, *2/*2, *2/*3, and *3/*3) result in an inherently higher warfarin half-life and risk for warfarin-associated bleeding. CYP2C9 poor metabolizers generally require lower anticoagulant doses and more time (>2 to 4 weeks) to achieve to achieve effective and safe anticoagulation than patients without these CYP2C9 variants.

PATIENT MANAGEMENT: Patients receiving concurrent therapy with medroxyprogesterone or megestrol and a coumarin anticoagulant (e.g. warfarin) should have their INR closely monitored.(1) When concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. INR) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling.

DISCUSSION: A study of four patients on high-dose progestins (two patients on medroxyprogesterone 500 mg twice daily and two patients on megestrol 160 mg once daily) and warfarin found that the progestins decreased the clearance of warfarin by 34.8% (from 2.3 to 1.5 mL/h*kg BW) and increased the half-life of warfarin by 71.4% (from 43.4 to 74.4 hours).(2)

There is no enhanced messaging for this drug.

• Carcinoma of breast
• Porphyria

• Abnormal vaginal bleeding
• Acute myocardial infarction
• Benign hepatic cell adenoma
• Cardiomyopathy
• Cerebrovascular accident
• Chronic kidney disease stage 5 (failure) GFr<15 ml/min
• Coronary artery disease
• Deep venous thrombosis
• Diabetes mellitus
• Hepatic cirrhosis
• Hyperlipidemia
• Hypertension
• Malignant neoplasm of liver
• Meningioma
• Nephrotic syndrome
• Osteopenia
• Osteoporosis
• Predisposition to thrombosis
• Pulmonary thromboembolism
• Sickle cell disease
• Thromboembolic disorder
• Thrombophlebitis

• Systemic lupus erythematosus

There is no enhanced messaging for this drug.

Less Frequent

• Depression

Rare or Very Rare

• Anaphylaxis
• Anemia
• Angioedema
• Arterial thrombosis
• Carcinoma of cervix
• Deep venous thrombosis
• Endometrial hyperplasia
• Erythema multiforme
• Erythema nodosum
• Facial palsy
• Fracture
• Galactorrhea not associated with childbirth
• Hypercalcemia
• Hypercortisolism
• Jaundice
• Meningioma
• Neoplasm of breast
• Obstructive hyperbilirubinemia
• Osteopenia
• Osteoporosis
• Papilledema
• Pulmonary thromboembolism
• Rectal bleeding
• Retinal thrombosis
• Scleroderma
• Seizure disorder
• Squamous cell carcinoma of cervix
• Thromboembolic disorder
• Thrombophlebitis

More Frequent

• Abnormal uterine bleeding
• Acute abdominal pain
• Dizziness
• Headache disorder
• Injection site sequelae
• Libido changes
• Menstrual disorder
• Nervousness
• Weight gain

Less Frequent

• Abdominal distension
• Acne vulgaris
• Alopecia
• Anorexia
• Arthralgia
• Back pain
• Cervical discharge
• Chest pain
• Constipation
• Cramps in legs
• Drug-induced hot flash
• Dysmenorrhea
• Dyspnea
• Dysuria
• Edema
• Fatigue
• General weakness
• Insomnia
• Irritability
• Mastalgia
• Nausea
• Ocular pain
• Pain in extremities
• Skin rash
• Symptoms of anxiety
• Tachycardia
• Urinary tract infection
• Vaginal discharge
• Vaginitis
• Vomiting

Rare or Very Rare

• Abnormal glucose tolerance
• Amenorrhea
• Appetite changes
• Body fluid retention
• Body odor
• Chloasma
• Drowsy
• Dry skin
• Dyspareunia
• Euphoria
• Fever
• Hirsutism
• Hoarseness
• Increased libido
• Induration of skin
• Lactation deficiency
• Lipodystrophy
• Malaise
• Paresthesia
• Polydipsia
• Pruritus of skin
• Urticaria
• Varicose veins

No enhanced messaging available.

No enhanced messaging available.

Although progestins have been used beginning in the first trimester of pregnancy to prevent habitual abortion or to treat threatened abortion, there is no adequate evidence from well-controlled studies to substantiate the efficacy of progestins for these uses; however, there is evidence of potential adverse effects on the fetus when these drugs are administered within the first 4 months of pregnancy. In addition, in most women, the cause of abortion is a defective ovum, which progestins could not be expected to influence. Because of their uterine-relaxant effects, progestins may delay spontaneous abortion of fertilized defective ova. Masculinization of the female fetus has reportedly occurred when progestins were used during pregnancy. Clitoral hypertrophy and fusion of the labia have been reported in a few female neonates born to women who had received medroxyprogesterone during pregnancy; hypospadias in male neonates born to women receiving progestational agents occurs at approximately twice the rate of occurrence in male neonates born to women not receiving the drugs. Postpartum bleeding, postabortal bleeding, and missed abortion have been reported in women who received the drug during pregnancy. An association between intrauterine exposure to female sex hormones and congenital anomalies, including cardiovascular and limb defects, has been suggested. (See Cautions: Pregnancy, Fertility, and Lactation, in Estrogen-Progestin Combinations 68:12.) Use of progestins, including medroxyprogesterone, is not recommended during the first 4 months of pregnancy. If a woman becomes pregnant while receiving medroxyprogesterone or is inadvertently exposed to the drug during the first 4 months of pregnancy, she should be advised of the potential risks to the fetus. To increase ensurance that the drug is not administered inadvertently to a pregnant woman, it is important that use of the drug be initiated only during the first 5 days after onset of normal menses, within 5 days postpartum if the woman is not lactating, or at the sixth postpartum week if she is. If more than 13-14 weeks has elapsed since the last dose of medroxyprogesterone, appropriate assessment should be performed to ensure that the woman is not pregnant prior to administering a dose.

When medroxyprogesterone is used as a contraceptive, unintended pregnancies that occur within 1-2 months after IM injection of the drug may be characterized by impaired fetal growth as evidenced by low birthweights, which theoretically could result in an increased risk of neonatal death. However, the attributable risk of this adverse effect is low because such pregnancies are unlikely. The risk of low birthweight was particularly evident when conception was estimated to occur within 4 weeks of medroxyprogesterone injection. While an increase in polysyndactyly, particularly among offspring of women younger than 30 years of age, and chromosomal anomalies also have been observed in neonates born to women who received IM medroxyprogesterone contraception, the unrelated nature of these effects, the lack of confirmation from other studies, the prolonged period of time between use of the drug and conception in many cases, and chance effects resulting from the multiple statistical comparisons applied make an association between these effects and the drug unlikely.

The possibility of ectopic pregnancy should be considered in any women using medroxyprogesterone contraception if pregnancy occurs or the woman develops complaints of severe abdominal pain.

Medroxyprogesterone should not be used to induce withdrawal bleeding as a test for pregnancy.

Progestins reportedly are distributed into milk, and detectable amounts of medroxyprogesterone have been identified in milk of lactating women receiving the drug IM. Milk composition, quality, and volume are not affected adversely by medroxyprogesterone use. While the manufacturers warn that the possible effects of progestins in milk on nursing infants have not been determined, study of infants exposed to the drug via breast milk has revealed no evidence of adverse developmental or behavioral effects through puberty.

The effects of combined medroxyprogesterone acetate and estradiol cypionate therapy on lactation and nursing infants have not been established. However, because adverse effects such as jaundice and breast enlargement have been reported in nursing infants of women receiving estrogen-progestin combination oral contraceptives, the usual cautions and precautions associated with estrogens must be considered in lactating women receiving IM medroxyprogesterone acetate in fixed combination with estradiol cypionate. The manufacturer states that use of estrogen-progestin combination contraceptives should be deferred until 6 weeks postpartum. For additional information, see Cautions: Pregnancy, Fertility, and Lactation, in Estrogen-Progestin Combinations 68:12.

No enhanced messaging available.