Phytomulti (multivit with minerals/lycopene/lutein/herbal complex no.219)

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

Cyp1a2 Inhibitors/Fezolinetant

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: Inhibitors of CYP1A2 may inhibit the metabolism of fezolinetant.(1-4)

CLINICAL EFFECTS: Concurrent use of a CYP1A2 inhibitor may increase levels of and adverse effects from fezolinetant.(1-4)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Recommendations for concurrent use of fezolinetant with CYP1A2 inhibitors differ in different regions. The US manufacturer of fezolinetant states that concurrent use with strong, moderate, and weak CYP1A2 inhibitors is contraindicated.(1) The Australian, Canadian, and UK manufacturers of fezolinetant state that concurrent use with strong and moderate CYP1A2 inhibitors is contraindicated, while weak CYP1A2 inhibitors are not predicted to cause clinically relevant changes in fezolinetant exposure.(2-4)

DISCUSSION: In a study, fluvoxamine, a strong CYP1A2 inhibitor, increased fezolinetant maximum concentration (Cmax) and area-under-curve (AUC) by 80% and 840%, respectively. Mexiletine (400 mg every 8 hours), a moderate CYP1A2 inhibitor, increased fezolinetant Cmax and AUC by 40% and 360%, respectively. Cimetidine (300 mg every 6 hours), a weak CYP1A2 inhibitor, increased fezolinetant Cmax and AUC by 30% and 100%, respectively.(1) Strong CYP1A2 inhibitors linked to this monograph include angelica root, ciprofloxacin, enasidenib, enoxacin, fluvoxamine, and rofecoxib. Moderate CYP1A2 inhibitors linked to this monograph include capmatinib, centanafadine, dipyrone, fexinidazole, genistein, hormonal contraceptives, methoxsalen, mexiletine, osilodrostat, phenylpropanolamine, pipemidic acid, rucaparib, troleandomycin, vemurafenib, and viloxazine. Weak CYP1A2 inhibitors linked to this monograph include acyclovir, allopurinol, artemisinin, belumosudil, caffeine, cannabidiol, cimetidine, curcumin, dan-shen, deferasirox, disulfiram, Echinacea, famotidine, ginseng, norfloxacin, obeticholic acid, parsley, piperine, propafenone, propranolol, ribociclib, simeprevir, thiabendazole, ticlopidine, triclabendazole, valacyclovir, verapamil, and zileuton.(5-7)

P-Glycoprotein (P-GP) Inducers/Vincristine

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: Inducers of P-glycoprotein (P-gp) may reduce systemic exposure to vincristine.(1)

CLINICAL EFFECTS: Concurrent or recent use of P-gp inducers may result in decreased effectiveness of vincristine.(1)

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

PATIENT MANAGEMENT: The US manufacturer of vincristine states that concurrent use of P-gp inducers should be avoided.(1) Consider the use of agents with no or minimal induction potential if possible. Monitor patients for decreased response to therapy.

DISCUSSION: Vincristine is transported by P-gp and inducers of this transporter are expected to decrease levels of vincristine.(1) Inducers of P-gp include linked to this monograph include: efavirenz, green tea, and lorlatinib.(2,3)

P-Glycoprotein (P-GP) Inducers; Phenobarbital/Ravidasvir

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: Inducers of P-glycoprotein (P-gp) may decrease the absorption of ravidasvir.(1)

CLINICAL EFFECTS: Concurrent or recent use of a P-gp inducer may result in decreased levels and effectiveness of ravidasvir.(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 ravidasvir states concurrent use with P-gp inducers is contraindicated.(1)

DISCUSSION: Interaction studies with P-gp inducers have not been performed. Co-administration with potent inducers of P-gp are expected to decrease ravidasvir plasma concentrations and result in therapeutic failure.(1) Agents linked to this monograph include apalutamide, carbamazepine, fosphenytoin, green tea, lorlatinib, phenobarbital, phenytoin, primidone, quercetin, rifabutin, rifampin, and St. John's wort.(1-3)

Weak Cyp3a4 Inhibitors/Lemborexant (> 5 MG)

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: Inhibitors of CYP3A4 may inhibit the metabolism of lemborexant.(1)

CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP3A4 may result in increased levels of and effects from lemborexant, including somnolence, fatigue, CNS depressant effects, daytime impairment, headache, and nightmare or abnormal dreams.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The maximum recommended dose of lemborexant with concurrent use of a weak CYP3A4 inhibitors should not exceed 5 mg per dose.(1) For patients on avapritinib: this interaction applies only to gastrointestinal stromal tumor (GIST) patients on avapritinib 200 mg or 300 mg.(2)

DISCUSSION: Lemborexant is a CYP3A4 substrate. In a PKPB model, concurrent use of lemborexant with itraconazole increased area-under-curve (AUC) and concentration maximum (Cmax) by 3.75-fold and 1.5-fold, respectively. Concurrent use of lemborexant with fluconazole increased AUC and Cmax by 4.25-fold and 1.75-fold, respectively.(1) Weak inhibitors of CYP3A4 include: amiodarone, amlodipine, anamorelin, asciminib, avapritinib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, camizestrant, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, vepdegestrant, viloxazine, vonoprazan, and ziftomenib.(1,3)

Weak Cyp3a4 Inhibitors/Ubrogepant (> 50 MG)

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: Weak inhibitors of CYP3A4 may inhibit the metabolism of ubrogepant.(1)

CLINICAL EFFECTS: Concurrent use of ubrogepant with weak CYP3A4 inhibitors may result in an increase in exposure of ubrogepant.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when used concomitantly with weak CYP3A4 inhibitors. Initial dose of ubrogepant should not exceed 50 mg when used concomitantly with weak inhibitors of CYP3A4. A second dose may be given within 24 hours but should not exceed 50 mg when used concurrently with weak CYP3A4 inhibitors.(1) For patients on avapritinib: this interaction applies only to gastrointestinal stromal tumor (GIST) patients on avapritinib 200 mg or 300 mg.(2)

DISCUSSION: Coadministration of ubrogepant with verapamil, a moderate CYP3A4 inhibitor, resulted in a 3.5-fold and 2.8-fold increase in area-under-curve (AUC) and concentration maximum (Cmax), respectively. No dedicated drug interaction study was conducted to assess concomitant use with weak CYP3A4 inhibitors. The conservative prediction of the maximal potential increase in ubrogepant exposure with weak CYP3A4 inhibitors is not expected to be more than 2-fold.(1) Weak inhibitors of CYP3A4 include: amiodarone, amlodipine, anamorelin, asciminib, avapritinib, azithromycin, Baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, camizestrant, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, delavirdine, deutivacaftor, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, maribavir, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, pirtobrutinib, propiverine, propofol, ranitidine, ranolazine, resveratrol, roxithromycin, rucaparib, simeprevir, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, vepdegestrant, viloxazine, vonoprazan, and ziftomenib. (3,4)

Xanthine Derivatives/Adenosine; Hexobendine; Regadenoson

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: Xanthine derivatives may antagonize the effects of endogenous(1) and exogenous adenosine,(2,3) regadenoson,(4) and hexobendine.(5)

CLINICAL EFFECTS: Concurrent use of a xanthine derivative use may result in decreased effectiveness of adenosine, hexobendine and regadenoson. Aminophylline may increase the risk of adenosine-induced seizures.(3)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients receiving concurrent therapy with adenosine and a xanthine derivative should be monitored for decreased effectiveness of adenosine. The dosage of adenosine may need to be increased. Whenever possible, withhold xanthine derivatives for 5 half-lives prior to using adenosine in cardiac stress tests.(6) Methylxanthines should not be used to reverse the effects of adenosine in patients who experience adenosine-induced seizures.(3) Concurrent therapy with hexobendine and a xanthine oxidase derivative should also be monitored for decreased effectiveness of hexobendine.(5) The US manufacturer of regadenoson recommends that patients avoid methylxanthines (e.g. caffeine, pentoxifylline, and theophylline) for 12 hours prior to regadenoson administration. Aminophylline may be used to attenuate severe and/or persistent adverse reactions to regadenoson.(4)

DISCUSSION: In a study in six healthy subjects, theophylline significantly reduced the heart-rate response to adenosine. In addition, theophylline reduced the amount of abdominal and chest discomfort reported by subjects, allowing significantly higher infusion rates of adenosine.(7) Theophylline has also been reported to antagonize the vasorelaxant action of adenosine in human forearm arterioles.(8) In a study in five subjects, theophylline decreased the amounts of adenosine-induced side effects, including chest pain. There was no change in blood pressure or respiratory rate during concurrent adenosine and theophylline.(9) In a study in ten dog and twelve human subjects, the administration of adenosine after hexobendine increased coronary sinus blood flow. Aminophylline administration significantly decreased the coronary vasodilation response to adenosine and hexobendine.(5) In a study in ten healthy subjects, caffeine reduced the mean adenosine-induced increases in systolic blood pressure by 7.2 mmHg and heart rate by 8.4 beats/min when compared to placebo.(2) In another study in ten healthy subjects, caffeine was shown to lower the adenosine-induced response of blood pressure and heart rate.(3) Caffeine has also been reported to reduced adenosine-induced changes in minute ventilation and tidal volume.(3) Aminophylline has been shown to shorten the duration of coronary blood flow response to regadenoson.(3) Coronary flow reserve was 8% lower in patients who received caffeine (200 mg single dose) 2 hours prior to regadenoson administration when compared to subjects who received placebo instead of caffeine.(4)

Xanthine Derivatives/Dipyridamole Injectable

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: The xanthine derivatives are adenosine receptor antagonists. Concurrent administration may inhibit dipyridamole-induced increases in endogenous plasma adenosine levels, thus decreasing dipyridamole's vasodilator effects.(1)

CLINICAL EFFECTS: Concurrent administration may result in a decrease in dipyridamole's vasodilator effects. This may produce false-negative results during dipyridamole-thallium imaging tests.(1-3)

PREDISPOSING FACTORS: In patients with congestive heart failure and decreased hepatic function, the metabolism of xanthine derivatives may be decreased. These patients may need a longer xanthine-free period prior to dipyridamole-thallium imaging tests.(2)

PATIENT MANAGEMENT: Patients scheduled for dipyridamole-thallium imaging tests should have a xanthine-free period (including caffeine-containing products) for at least 24 hours prior to their exam.(3)

DISCUSSION: In a study in eight male subjects with documented coronary artery disease, intravenous dipyridamole administered during a dipyridamole-thallium 201 SPECT image test produced a significant increase in heart rate, a decrease in blood pressure, and angina in seven patients and ST segment depression in four patients. SPECT imaging showed reversible perfusion defects in myocardial segments supplied by stenotic coronary arteries. When the exam was repeated when the subjects were receiving therapeutic dosages of theophylline, there was no appearance of angina, ST depression, or hemodynamic changes and SPECT imaging shown total absence of reversible perfusion defects.(1) A study in eight patients with coronary artery disease evaluated the effects of caffeine on dipyridamole-201Tl myocardial imaging. The administration of dipyridamole alone resulted in chest pain and ST-segment depression in four patients. Concurrent caffeine infusion decreased the dipyridamole-induced decrease in blood pressure and heart rate. No patients experience chest pain or ST-segment depression. Six patients had false negative test results.(2) Another study found that the attenuation of the hemodynamic response to dipyridamole by caffeine was dose-dependent.(3)

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

Agents That Affect Iodide/Radioactive Iodide

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

MECHANISM OF ACTION: Many compounds can affect iodide protein binding and alter iodide pharmacokinetics and pharmacodynamics.(1)

CLINICAL EFFECTS: Compounds that affect iodide pharmacokinetics and pharmacodynamics may impact the effectiveness of radioactive iodide.(1)

PREDISPOSING FACTORS: Compounds that affect iodide pharmacokinetics and pharmacodynamics are expected to have the most impact during therapy using radioactive iodide. Diagnostic procedures would be expected to be impacted less.

PATIENT MANAGEMENT: Discuss the use of agents that affect iodide pharmacokinetics and pharmacodynamics with the patient's oncologist.(1) Because indocyanine green contains sodium iodide, the iodine-binding capacity of thyroid tissue may be reduced for at least one week following administration. Do not perform radioactive iodine uptake studies for at least one week following administration of indocyanine green.(2) The manufacturer of iopamidol states administration may interfere with thyroid uptake of radioactive iodine and decrease therapeutic and diagnostic efficacy. Avoid thyroid therapy or testing for up to 6 weeks post administration of iopamidol.(3)

DISCUSSION: Many agents interact with radioactive iodine. The average duration of effect is: anticoagulants - 1 week antihistamines - 1 week anti-thyroid drugs, e.g: carbimazole, methimazole, propylthiouracil - 3-5 days corticosteroids - 1 week iodide-containing medications, e.g: amiodarone - 1-6 months expectorants - 2 weeks Lugol solution - 3 weeks saturated solution of potassium iodine - 3 weeks vitamins - 10-14 days iodide-containing X-ray contrast agents - up to 1 year lithium - 4 weeks phenylbutazone - 1-2 weeks sulfonamides - 1 week thyroid hormones (natural or synthetic), e.g.: thyroxine - 4 weeks tri-iodothyronine - 2 weeks tolbutamide - 1 week topical iodide - 1-9 months (1)

Agents That Affect Iodide/Sodium Iodide I 131

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

MECHANISM OF ACTION: Many compounds can affect iodide protein binding and alter iodide pharmacokinetics and pharmacodynamics.(1,2)

CLINICAL EFFECTS: Compounds that affect iodide pharmacokinetics and pharmacodynamics may impact the effectiveness of radioactive iodide.(1,2)

PREDISPOSING FACTORS: Compounds that affect iodide pharmacokinetics and pharmacodynamics are expected to have the most impact during therapy using radioactive iodide. Diagnostic procedures would be expected to be impacted less.

PATIENT MANAGEMENT: Discuss the use of agents that affect iodide pharmacokinetics and pharmacodynamics with the patient's oncologist.(1,2) Because indocyanine green contains sodium iodide, the iodine-binding capacity of thyroid tissue may be reduced for at least one week following administration. Do not perform radioactive iodine uptake studies for at least one week following administration of indocyanine green.(3) The manufacturer of iopamidol states administration may interfere with thyroid uptake of radioactive iodine and decrease therapeutic and diagnostic efficacy. Avoid thyroid therapy or testing for up to 6 weeks post administration of iopamidol.(4)

DISCUSSION: Many agents interact with radioactive iodine. The average duration of effect is: anticoagulants - 1 week antihistamines - 1 week anti-thyroid drugs, e.g: carbimazole, methimazole, propylthiouracil - 3-5 days corticosteroids - 1 week iodide-containing medications, e.g: amiodarone - 1-6 months expectorants - 2 weeks Lugol solution - 3 weeks saturated solution of potassium iodine - 3 weeks vitamins - 10-14 days iodide-containing X-ray contrast agents - up to 1 year lithium - 4 weeks phenylbutazone - 1-2 weeks sulfonamides - 1 week thyroid hormones (natural or synthetic), e.g.: thyroxine - 4 weeks tri-iodothyronine - 2 weeks tolbutamide - 1 week topical iodide - 1-9 months (1,2)

Aluminum & Magnesium Antacids;Polyvalent Cations/Raltegravir

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

MECHANISM OF ACTION: Aluminum and/or magnesium containing antacids may alter raltegravir absorption by altering gastric pH. Magnesium antacids and supplements containing polyvalent cations may bind to raltegravir in the GI tract, preventing its absorption.(1)

CLINICAL EFFECTS: Aluminum and/or magnesium containing antacids and supplements containing polyvalent cations may reduce levels and clinical effectiveness of raltegravir.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Concurrent use of any formulation of raltegravir and aluminum and/or magnesium antacids is not recommended. Instruct patients not to use aluminum and/or magnesium containing antacids. Calcium carbonate may be used in place of aluminum and/or magnesium containing antacids in patients receiving raltegravir twice daily. Calcium carbonate is not recommended for patients receiving once daily raltegravir (1,200 mg daily).(1,2) The US HIV treatment guidelines state that if coadministration of other medications that contain polyvalent cations (e.g., Mg, Al, Fe, Ca, Zn, sucralfate) is necessary, administer raltegravir at least 2 hours before or at least 6 hours after polyvalent cations. Monitor for virologic response.(2)

DISCUSSION: Simultaneous administration of aluminum and magnesium hydroxide (20 ml) with raltegravir (400 mg BID) decreased raltegravir maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) by 44%, 49%, and 63%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 2 hours before raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 51%, 51%, and 56%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 2 hours after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 22%, 30%, and 57%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 4 hours before after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 22%, 19%, and 60%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 4 hours after after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 30%, 32%, and 62%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 6 hours before after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 10%, 13%, and 50%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 6 hours after after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 10%, 11%, and 49%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 12 hours after after raltegravir (1200 mg single dose) decreased raltegravir Cmax, AUC, and Cmin by 14%, 14%, and 58%, respectively.(1,3) Data from in vitro(3) and in vivo simulations(5) suggest that magnesium's effect on raltegravir may involve chelation as well as changes in pH.

Selected Moderate And Weak Cyp1a2 Inhibitors/Tizanidine

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

MECHANISM OF ACTION: Moderate and weak CYP1A2 inhibitors may inhibit the metabolism of tizanidine by CYP1A2.(1)

CLINICAL EFFECTS: Concurrent use of moderate and weak CYP1A2 inhibitors may result in elevated levels of and effects from tizanidine, including hypotension, bradycardia, drowsiness, sedation, and decreased psychomotor function.

PREDISPOSING FACTORS: The risk of anticholinergic toxicities including cognitive decline, delirium, falls and fractures is increased in geriatric patients using more than one medicine with anticholinergic properties.(2)

PATIENT MANAGEMENT: The US manufacturer of tizanidine states that concurrent use of tizanidine with inhibitors of CYP1A2 should be avoided.(3) If adverse reactions such as hypotension, bradycardia or excessive drowsiness occur, reduce tizanidine dosage or discontinue tizanidine therapy.(3)

DISCUSSION: In a study, cannabidiol 750 mg twice daily (a weak CYP1A2 inhibitor) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a 200 mg single dose of caffeine (a sensitive CYP1A2 substrate) by 15% and 95%, respectively.(1) In a study in 10 healthy subjects, concurrent fluvoxamine, a strong inhibitor of CYP1A2, increased tizanidine Cmax, AUC, and half-life (T1/2) by 12-fold, 33-fold, and 3-fold, respectively. Significant decreases in blood pressure and increases in drowsiness and psychomotor impairment occurred.(3) In a study in 10 healthy subjects, concurrent ciprofloxacin, a strong inhibitor of CYP1A2, increased tizanidine Cmax and AUC by 7-fold and 10-fold, respectively. Significant decreases in blood pressure and increases in drowsiness and psychomotor impairment occurred.(3) Moderate CYP1A2 inhibitors linked to this monograph include: centanafadine, dipyrone, fexinidazole, genistein, methoxsalen, phenylpropanolamine, pipemidic acid, propranolol, rucaparib, and troleandomycin. Weak CYP1A2 inhibitors linked to this monograph include: allopurinol, artemisinin, belumosudil, caffeine, cannabidiol, curcumin, dan-shen, disulfiram, Echinacea, ginseng, parsley, piperine, ribociclib, simeprevir, thiabendazole, and triclabendazole.(4)

Weak Cyp3a4 Inhibitors/Eliglustat

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

MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of eliglustat. If the patient is also taking an inhibitor of CYP2D6, eliglustat metabolism can be further inhibited.(1)

CLINICAL EFFECTS: Concurrent use of an agent that is a weak inhibitor of CYP3A4 may result in elevated levels of and clinical effects of eliglustat, including prolongation of the PR, QTc, and/or QRS intervals, which may result in life-threatening cardiac arrhythmias.(1)

PREDISPOSING FACTORS: If the patient is also taking an inhibitor of CYP2D6, is a poor metabolizer of CYP2D6, and/or has hepatic impairment, eliglustat metabolism can be further inhibited.(1) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The concurrent use of eliglustat with weak inhibitors of CYP3A4 in poor metabolizers of CYP2D6 should be avoided.(1) The dosage of eliglustat with weak inhibitors of CYP3A4 in extensive metabolizers of CYP2D6 with mild (Child-Pugh Class A) hepatic impairment should be limited to 84 mg daily.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. For patients on avapritinib: this interaction applies only to gastrointestinal stromal tumor (GIST) patients on avapritinib 200 mg or 300 mg.(3)

DISCUSSION: Ketoconazole (400 mg daily), a strong inhibitor of CYP3A4, increased eliglustat (84 mg BID) maximum concentration (Cmax) and area-under-curve (AUC) by 4-fold and 4.4-fold, respectively, in extensive metabolizers. Physiologically-based pharmacokinetic (PKPB) models suggested ketoconazole would increase eliglustat Cmax and AUC by 4.4-fold and 5.4-fold, respectively, in intermediate metabolizers. PKPB models suggested ketoconazole may increase the Cmax and AUC of eliglustat (84 mg daily) by 4.3-fold and 6.2-fold, respectively, in poor metabolizers.(1) PKPB models suggested fluconazole, a moderate inhibitor of CYP3A4, would increase eliglustat Cmax and AUC by 2.8-fold and 3.2-fold, respectively, in extensive metabolizers and by 2.5-fold and 2.9-fold, respectively in intermediate metabolizers. PKPB models suggest that concurrent eliglustat (84 mg BID), paroxetine (a strong inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 16.7-fold and 24.2-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 7.5-fold and 9.8-fold, respectively.(1) PKPB models suggest that concurrent eliglustat (84 mg BID), terbinafine (a moderate inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 10.2-fold and 13.6-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 4.2-fold and 5-fold, respectively.(1) Weak inhibitors of CYP3A4 include: amlodipine, anamorelin, asciminib, avapritinib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, camizestrant, cannabidiol, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranolazine, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, vepdegestrant, vonoprazan, and ziftomenib.(4,5)

Weak Cyp3a4 Inhibitors/Lomitapide

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

MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of lomitapide.(1) Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Thus even weak CYP3A4 inhibitors may affect lomitapide exposure (AUC, area-under-curve).

CLINICAL EFFECTS: Concurrent use of a weak inhibitor of CYP3A4 may result in 2-fold increases in lomitapide levels and toxicity from lomitapide.(1)

PREDISPOSING FACTORS: This interaction may be more severe in patients with hepatic impairment or with end-stage renal disease.(1)

PATIENT MANAGEMENT: When initiating lomitapide in patients taking a stable dose of a weak CYP3A4 inhibitor, follow the recommended dose and titration schedule per labeling. When initiating a weak CYP3A4 inhibitor in patients taking lomitapide, decrease the dose of lomitapide by 50%. The maximum recommended lomitapide dose with concurrent weak CYP3A4 inhibitors should be: -Adults (age 18 years and older): 30 mg daily, -Age group 11 to 17 years: 20 mg daily, -Age group 2 to 10 years: 10 mg daily. Due to lomitapide's long half-life, it may take 1 to 2 weeks to see the full effect of this interaction.(1) For patients on avapritinib: this interaction applies only to gastrointestinal stromal tumor (GIST) patients on avapritinib 200 mg or 300 mg.(2)

DISCUSSION: Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Based upon interactions with stronger inhibitors, weak inhibitors of CYP3A4 are predicted to increase lomitapide area-under-curve(AUC) 2-fold.(1) Weak CYP3A4 inhibitors linked to this interaction include: amiodarone, amlodipine, anamorelin, asciminib, atorvastatin, avapritinib, azithromycin, Baikal skullcap, belumosudil, bicalutamide, blueberry juice, brodalumab, camizestrant, cannabidiol, capivasertib, cilostazol, cimetidine, ciprofloxacin, chlorzoxazone, clotrimazole, cranberry juice, cyclosporine, daridorexant, delavirdine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lurasidone, maribavir, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, resveratrol, roxithromycin, rucaparib, selpercatinib, sevabertinib, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, vepdegestrant, viloxazine, vonoprazan, ziftomenib, and zileuton.(1-3)

Weak Cyp3a4 Inhibitors/Pimozide

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

MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of pimozide.(1,2)

CLINICAL EFFECTS: Concurrent use with weak CYP3A4 inhibitors may increase the levels and effects of pimozide including QTc prolongation and potentially life-threatening cardiac arrhythmias like torsades de pointes.(1-2) Concurrent use may also result in extrapyramidal symptoms such as akathisia, bradykinesia, cogwheel rigidity, dystonia, hypertonia, and oculogyric crisis.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increased systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) The risk of anticholinergic toxicities including cognitive decline, delirium, falls and fractures is increased in geriatric patients using more than one medicine with anticholinergic properties.(4)

PATIENT MANAGEMENT: The US manufacturer of pimozide states that concomitant treatment with strong CYP3A4 inhibitors is contraindicated and treatment with less potent inhibitors of CYP3A4 should also be avoided.(1) The UK manufacturer of pimozide contraindicates concomitant use of pimozide with CYP3A4 inhibitors and CYP2D6 inhibitors, stating that inhibition of either or both CYP3A4 and CYP2D6 may result in the elevation of pimozide blood concentration and increase the possibility of QT-prolongation.(2) For patients on avapritinib: this interaction applies only to gastrointestinal stromal tumor (GIST) patients on avapritinib 200 mg or 300 mg.(5) If concurrent use cannot be avoided, then correct or minimize QT prolonging risk factors, use the lowest effective dose of pimozide, and discontinue other concurrent QT prolonging agents or CYP3A4 or CYP2D6 inhibitors if possible. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: Pimozide is metabolized at CYP3A.(1,5) Elevated levels of pimozide may prolong the QTc interval resulting in life-threatening ventricular arrhythmias.(1) Serious cardiovascular events, including QT prolongation, torsades de pointes, ventricular tachycardia, cardiac arrest, and/or sudden death have been reported in patients taking pimozide in combination with itraconazole and/or other CYP3A4 inhibitors.(1,2) Weak CYP3A4 inhibitors include: amlodipine, asciminib, avapritinib, belumosudil, berberine, bicalutamide, blueberry, brodalumab, camizestrant, cannabidiol, capivasertib, chlorzoxazone, cimetidine, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fostamatinib, ginkgo, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, marijuana, olaparib, palbociclib, peppermint, piperine, pirtobrutinib, propiverine, ranitidine, resveratrol, scutellarin, sevabertinib, simeprevir, sitaxsentan, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(7,8)

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

Caffeine-Containing Products/Migalastat

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.

CLINICAL EFFECTS: Concurrent use of a caffeine-containing product may result in decreased levels and effectiveness of migalastat.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid coadministration of migalastat with caffeine-containing products. Do not administer caffeine-containing products within 2 hours before and 2 hours after taking migalastat.(1)

DISCUSSION: Coadministration of migalastat with caffeine 190 mg decreased the migalastat maximum concentration (Cmax) by 60% and area-under-curve (AUC) by 55%.(1)

Green Tea/Nadolol

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

MECHANISM OF ACTION: Nadolol is a substrate of OATP1A2, an influx transporter found in intestinal epithelium. Green tea catechins inhibit several drug transporters, including OATP1A2, leading to decreased absorption of nadolol. P-glycoprotein may also be involved, however no studies have confirmed its role.

CLINICAL EFFECTS: Concomitant use of nadolol with green tea or green tea catechins may decrease the effectiveness of nadolol.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Advise patients maintained on nadolol to avoid green tea and green tea supplements.

DISCUSSION: In a randomized crossover study in 10 healthy subjects, concurrent use of nadolol (30 mg daily) and green tea (700 mL/day), decreased the maximum concentration (Cmax) and area-under-curve (AUC) of nadolol by 85.3% and 85%, respectively. Pharmacodynamic parameters assessed included pulse rate, systolic blood pressure, and diastolic blood pressure. Although all parameters were affected slightly, nadolol's systolic blood pressure lowering effect was significantly suppressed (p = 0.042).(1)

Moderate And Weak Cyp3a4 Inhibitors/Tacrolimus

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

MECHANISM OF ACTION: Moderate and weak inhibitors of CYP3A4 may inhibit the metabolism of tacrolimus.(1)

CLINICAL EFFECTS: Concurrent use of a CYP3A4 inhibitor may result in elevated levels of and toxicity from tacrolimus, including nephrotoxicity, neurotoxicity, and prolongation of the QTc interval and life-threatening cardiac arrhythmias, including torsades de pointes.(1)

PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The US manufacturer of tacrolimus recommends monitoring tacrolimus whole blood trough concentrations and reducing tacrolimus dose if needed.(1) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting.

DISCUSSION: In a study of 26 renal transplant recipients, conjugated estrogens 3.75 mg daily increased the tacrolimus dose-corrected concentration of tacrolimus by 85.6%. Discontinuation of the conjugated estrogens led to a decrease in tacrolimus concentration of 46.6%.(3) A case report describes a 65-year-old kidney transplant recipient who was stable on tacrolimus 9 mg per day with trough levels of 5 to 7.5 ng/mL. Ten days after starting on estradiol gel 0.5 mg per day, her tacrolimus level rose to 18.3 ng/mL and serum creatinine (Scr) rose from 1.1 mg/dL at baseline to 2 mg/dL. Tacrolimus dose was reduced by 60%, and trough levels and Scr normalized after two weeks.(4) A study of 16 healthy volunteers found that elbasvir 50 mg/grazoprevir 200 mg daily increased the area-under-curve (AUC) of tacrolimus by 43%, while the maximum concentration (Cmax) of tacrolimus was decreased by 40%.(5) An analysis of FAERS data from 2004-2017, found a significant association between transplant rejection and concurrent use of tacrolimus and clotrimazole (reporting odds ratio 1.92, 95% CI). A retrospective study of 7 heart transplant patients on concurrent tacrolimus and clotrimazole troche showed a significant correlation between tacrolimus trough concentration and AUC after clotrimazole discontinuation. Tacrolimus clearance and bioavailability after clotrimazole discontinuation was 2.2-fold greater (0.27 vs. 0.59 L/h/kg) and the trough concentration decreased from 6.5 ng/mL at 1 day to 5.3 ng/mL at 2 days after clotrimazole discontinuation.(7) A retrospective study of 26 heart transplant patients found that discontinuation of concurrent clotrimazole with tacrolimus in the CYP3A5 expresser group had a 3.3-fold increase in apparent oral clearance and AUC of tacrolimus (0.27 vs. 0.89 L/h/kg) compared to the CYP3A5 non expresser group with a 2.2-fold mean increase (0.18 vs. 0.39 L/h/kg).(8) A study of 6 adult kidney transplant recipients found that clotrimazole (5-day course) increased the tacrolimus AUC 250% and the blood trough concentrations doubled (27.7 ng/ml versus 27.4 ng/ml). Tacrolimus clearance decreased 60% with coadministration of clotrimazole.(9) A case report describes a 23-year-old kidney transplant recipient who was stable on tacrolimus 5 mg twice daily, mycophenolate mofetil 30 mg daily, prednisone (30 mg daily tapered over time to 5 mg), and clotrimazole troche 10 mg four times daily. Discontinuation of clotrimazole resulted in a decrease in tacrolimus trough levels from 13.7 ng/ml to 5.4 ng/ml over a period of 6 days. Clotrimazole was restarted with tacrolimus 6 mg resulting in an increased tacrolimus level of 19.2 ng/ml.(10) A retrospective study in 95 heart transplant recipients on concurrent clotrimazole and tacrolimus found a median tacrolimus dose increase of 66.7% was required after clotrimazole discontinuation. Tacrolimus trough concentration was found to have decreased 42.5% after clotrimazole discontinuation.(11) A retrospective study in 65 pancreas transplant patients on concurrent tacrolimus, clotrimazole, cyclosporine, and prednisone found that clotrimazole discontinuation at 3 months after transplantation may cause significant tacrolimus trough level reductions.(12) A case report describes a 6-year-old kidney transplant recipient who was on a regimen of tacrolimus and mycophenolate mofetil. The patient was started letermovir 240 mg via G-tube 2 months post kidney transplant. One week after starting letermovir, the routine tacrolimus level showed a supratherapeutic concentration of 22.9 ng/L. A 36% dose reduction of tacrolimus was required. Upon discontinuation of letermovir, the tacrolimus level decreased by 42%.(13) Moderate CYP3A4 inhibitors linked to this monograph include: berotralstat, conivaptan, fluvoxamine, lenacapavir, letermovir, netupitant, nirogacestat, sevabertinib, stiripentol, and tofisopam.(6) Weak CYP3A4 inhibitors linked to this monograph include: avacopan, baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, camizestrant, chlorzoxazone, cimetidine, cranberry juice, daclatasvir, daridorexant, delavirdine, diosmin, elinzanetant, estrogens, flibanserin, fostamatinib, ginkgo biloba, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lazertinib, linagliptin, lomitapide, lumateperone, lurasidone, peppermint oil, piperine, propiverine, ranitidine, resveratrol, rimegepant, simeprevir, sitaxsentan, skullcap, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan-amoxicillin.(6)

Polyvalent Cations And Phosphate Binders/Vadadustat

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

MECHANISM OF ACTION: Vadadustat may form a chelate with iron supplements, phosphate binders, and other medicinal products whose primary component consists of polyvalent cations such as aluminum, calcium, magnesium, selenium, and zinc.(1)

CLINICAL EFFECTS: Simultaneous administration of vadadustat and polyvalent cations and phosphate binders decreases the exposure and effectiveness of vadadustat.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of vadadustat states that it should be administered at least 1 hour before or 2 hours after any medications or products whose primary component consists of iron, phosphate binders and polyvalent cations.(1)

DISCUSSION: Two studies evaluating the pharmacokinetics, safety, and tolerability of a single oral dose of vadadustat coadministered with a phosphate binder or iron supplement were conducted in healthy adult participants. Vadadustat exposure was reduced by coadministration with sevelamer carbonate, calcium acetate, ferric citrate, and ferrous sulfate. Geometric least squares mean ratios for area under the concentration-time curve (AUC) were reduced 37% to 55% by phosphate binders and 46% by ferrous sulfate. However, when vadadustat was administered 1 hour before phosphate binders, 90% confidence intervals for vadadustat exposure were within the no-effect boundaries of +50% to -33%, indicating that drug-drug interactions can be reduced by administering vadadustat 1 hour before phosphate binders.(2)

Polyvalent Cations/Baloxavir

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

MECHANISM OF ACTION: Aluminum, calcium, iron, magnesium, selenium, and zinc may form chelation compounds with baloxavir.(1)

CLINICAL EFFECTS: Simultaneous administration of products containing aluminum, calcium, iron, magnesium, selenium, and zinc may result in decreased levels of and clinical effects from baloxavir.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid concurrent administration of baloxavir with cation-containing products.(1)

DISCUSSION: A significant decrease in baloxavir exposure was observed when baloxavir was coadministered with calcium, aluminum, magnesium, or iron in monkeys. No studies have been conducted in humans.(1)

Polyvalent Cations/Penicillamine, Oral

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

MECHANISM OF ACTION: Penicillamine chelates with polyvalent cations such as aluminum, calcium, iron, magnesium, and zinc in the GI tract reducing the absorption of the penicillamine.

CLINICAL EFFECTS: Reduced (to 30% of fasting) bioavailability of penicillamine with decreased pharmacologic response.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: In order to assure systemic absorption and maximal effectiveness from penicillamine, counsel patient to separate penicillamine by at least 1 hour before or 1 hours after any medications or products containing polyvalent cations such as antacids or mineral supplements. Monitor clinical status for decreased effectiveness and adjust the penicillamine dose if necessary.

DISCUSSION: Clinical studies with polyvalent cations have not been conducted. Multivitamins with low doses of cations including iron and zinc may decrease penicillamine absorption so insure patient is aware of the risks.

Polyvalent Cations; Lanthanum; Sucralfate/Bictegravir

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

MECHANISM OF ACTION: Polyvalent cations, lanthanum, and sucralfate may bind to bictegravir in the GI tract, preventing its absorption.(1)

CLINICAL EFFECTS: Polyvalent cations, lanthanum and sucralfate may reduce levels and clinical effectiveness of bictegravir.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Bictegravir must be taken 2 hours before or 6 hours after polyvalent cations, lanthanum or sucralfate. Medicines containing calcium can be taken together with bictegravir if taken with food.(1) Some vitamin preparations may contain sufficient quantities of polyvalent cations to interact as well.

DISCUSSION: Simultaneous administration of aluminum and magnesium hydroxide (20 ml) in a fasted state with bictegravir (50 mg single dose) decreased bictegravir maximum concentration (Cmax) and area-under-curve (AUC) by 80% and 79%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 2 hours after bictegravir (50 mg single dose) in a fasted state decreased bictegravir Cmax and AUC by 7% and 13%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 2 hours before bictegravir (50 mg single dose) in a fasted state decreased bictegravir Cmax and AUC by 58% and 52%, respectively.(1) Simultaneous administration of aluminum and magnesium hydroxide (20 ml) in a fed state with bictegravir (50 mg single dose) decreased bictegravir Cmax and AUC by 49% and 47%, respectively.(1) Simultaneous administration of calcium carbonate (1200 mg single dose) in a fasted state with bictegravir (50 mg single dose) decreased bictegravir Cmax and AUC by 42% and 33%, respectively.(1) Simultaneous administration of calcium carbonate (1200 mg single dose) in a fed state with bictegravir (50 mg single dose) decreased bictegravir Cmax by 10% and increased AUC 3%, respectively.(1) Simultaneous administration of ferrous fumarate (324 mg single dose) in a fasted state with bictegravir (50 mg single dose) decreased bictegravir Cmax and AUC by 71% and 63%, respectively.(1) Simultaneous administration of ferrous fumarate (324 mg single dose) in a fed state with bictegravir (50 mg single dose) decreased bictegravir Cmax and AUC by 25% and 16%, respectively.(1)

Sel Oral Cations; Antacids; H2 Antag/Dolutegravir-Rilpivirin

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

MECHANISM OF ACTION: Aluminum, calcium, iron, lanthanum, magnesium, sucralfate, and zinc may form chelation compounds with dolutegravir.(1) Rilpivirine requires an acidic medium for absorption. Antacid or H2 antagonist induced decrease in gastric pH may result in decrease in rilpivirine absorption.(1)

CLINICAL EFFECTS: Simultaneous administration or administration of products containing aluminum, calcium, iron, lanthanum, magnesium, and/or sucralfate close to the administration time of dolutegravir may result in decreased absorption and clinical effectiveness of dolutegravir.(1) Simultaneous administration of an antacid or a H2 antagonist may result in decreased levels and effectiveness of rilpivirine, as well as the development of resistance.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: If possible, avoid concurrent therapy with dolutegravir-rilpivirine and cation-containing products. If it is necessary to use these agents concurrently, dolutegravir-rilpivirine should be administered 4 hours before or 6 hours after taking these medications.(1) Alternatively, dolutegravir-rilpivirine and supplements containing calcium or iron can be taken together with food.(1) In patients maintained on dolutegravir-rilpivirine, administer dolutegravir-rilpivirine at least 4 hours before or 6 hours after antacids .(1) In patients maintained on dolutegravir-rilpivirine, administer dolutegravir-rilpivirine at least 4 hours before or 12 hours after H2 antagonists.(1) Concurrent use of proton pump inhibitors will dolutegravir-rilpivirine is contraindicated.(1)

DISCUSSION: In a study in 16 subjects, the administration of an antacid (Maalox - aluminum and magnesium hydroxide) simultaneously with dolutegravir (50 mg single dose) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of dolutegravir by 72%, 74%, and 74%, respectively.(1) In a study in 16 subjects, the administration of an antacid (Maalox - aluminum and magnesium hydroxide) 2 hours after dolutegravir (50 mg single dose) decreased dolutegravir Cmax, AUC, and Cmin by 18%, 26%, and 30%, respectively.(1) In a study in 16 subjects, the administration of a multiple vitamin (One-A-Day) simultaneously with dolutegravir (50 mg single dose) decreased dolutegravir Cmax, AUC, and Cmin by 35%, 33%, and 32%, respectively.(1) In a study in 16 subjects, omeprazole (20 mg daily) decreased the Cmax, AUC, and Cmin of rilpivirine (150 mg daily) by 40%, 40%, and 33%, respectively. The Cmax and AUC of omeprazole decreased by 14% and 14%, respectively.(1) In a study in 24 subjects, famotidine (40 mg single dose) administered 12 hours before a single dose of rilpivirine (150 mg) had no significant effect on rilpivirine Cmax or AUC.(1) In a study in 23 subjects, famotidine (40 mg single dose) administered 2 hours before a single dose of rilpivirine (150 mg) decreased the rilpivirine Cmax and AUC by 85% and 76%, respectively.(1) In a study in 24 subjects, famotidine (40 mg single dose) administered 4 hours before a single dose of rilpivirine (150 mg) increased the rilpivirine Cmax and AUC by 21% and 13%, respectively.(1)

Selected Minerals, Oral/Trientine

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

MECHANISM OF ACTION: Mineral supplements may bind to trientine and block its absorption.

CLINICAL EFFECTS: The levels and clinical effects of trientine may be decreased.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of trientine states that mineral supplements should not be given with trientine. If concomitant therapy is necessary, take trientine on an empty stomach and separate administration at least one hour apart from any other drug. Monitor clinical status for decreased effectiveness and adjust the trientine dose if necessary.

DISCUSSION: Multivitamins with minerals may decrease trientine absorption so ensure patient is aware of the risks and counsel on instructions for concurrent use.

Selected Oral Cations/Dolutegravir

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

MECHANISM OF ACTION: Aluminum, calcium, iron, lanthanum, magnesium, sucralfate, and zinc may form chelation compounds with dolutegravir.(1)

CLINICAL EFFECTS: Simultaneous administration or administration of products containing aluminum, calcium, iron, lanthanum, magnesium, and/or sucralfate close to the administration time of dolutegravir may result in decreased absorption and clinical effectiveness of dolutegravir.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: If possible, avoid concurrent therapy with dolutegravir and cation-containing products. If it is necessary to use these agents concurrently, dolutegravir should be administered 2 hours before or 6 hours after taking these medications.(1) Alternatively, dolutegravir and supplements containing calcium or iron can be taken together with food.(1)

DISCUSSION: In a study in 16 subjects, the administration of an antacid (Maalox - aluminum and magnesium hydroxide) simultaneously with dolutegravir (50 mg single dose) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of dolutegravir by 72%, 74%, and 74%, respectively.(1) In a study in 16 subjects, the administration of an antacid (Maalox - aluminum and magnesium hydroxide) 2 hours after dolutegravir (50 mg single dose) decreased dolutegravir Cmax, AUC, and Cmin by 18%, 26%, and 30%, respectively.(1) In a study in 16 subjects, the administration of a multiple vitamin (One-A-Day) simultaneously with dolutegravir (50 mg single dose) decreased dolutegravir Cmax, AUC, and Cmin by 35%, 33%, and 32%, respectively.(1)

Selected Oral Cations/Elvitegravir

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

MECHANISM OF ACTION: The exact mechanism is unknown, but aluminum, calcium, iron, lanthanum, magnesium, sucralfate, and zinc may bind to elvitegravir in GI tract.

CLINICAL EFFECTS: Simultaneous administration or administration of products containing aluminum, calcium, iron, lanthanum, magnesium, and/or sucralfate may result in decreased levels and effectiveness of elvitegravir, as well as the development of resistance.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Separate the administration of elvitegravir and products containing aluminum, calcium, iron, lanthanum, magnesium, and/or sucralfate by at least 2 hours.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.

DISCUSSION: Administration of an antacid (exact formulation not stated) 2 hours before elvitegravir (50 mg) decreased the maximum concentration (Cmax), area-under-curve (AUC), or minimum concentration (Cmin) of elvitegravir by 18%, 15%, and 10%, respectively.(1) Administration of an antacid 2 hours after elvitegravir (50 mg) decreased the Cmax, AUC, or Cmin of elvitegravir by 21%, 20%, and 20%, respectively.(1) Administration of an antacid 4 hours before elvitegravir (50 mg) decreased the Cmax and AUC of elvitegravir by 5%, and 4%, respectively.(1) Administration of an antacid 4 hours before elvitegravir (50 mg) decreased both the Cmax and AUC of elvitegravir by 2%.(1)

Slt Moderate And Weak Cyp3a4 Inhibit/Sirolimus Protein-Bound

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

MECHANISM OF ACTION: Moderate and weak CYP3A4 inhibitors may inhibit the metabolism of sirolimus by CYP3A4.(1)

CLINICAL EFFECTS: Concurrent use of moderate or weak CYP3A4 inhibitors may result in elevated levels of and side effects from sirolimus.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of sirolimus protein-bound injection (Fyarro) states a dose reduction to 56 mg/m2 is recommended when used concurrently with moderate or weak CYP3A4 inhibitors. Concurrent use with strong CYP3A4 inhibitors should be avoided.(1)

DISCUSSION: In an open, randomized, cross-over trial in 18 healthy subjects, concurrent single doses of diltiazem (120 mg) and sirolimus (10 mg) increased sirolimus area-under-curve (AUC) and maximum concentration (Cmax) by 60% and by 43%, respectively. Sirolimus apparent oral clearance and volume of distribution decreased by 38% and 45%, respectively. There were no effects on diltiazem pharmacokinetics or pharmacodynamics.(2) In a study in 26 healthy subjects, concurrent sirolimus (2 mg daily) with verapamil (180 mg twice daily) increased sirolimus AUC and Cmax by 2.2-fold and 2.3-fold, respectively. The AUC and Cmax of the active S-enantiomer of verapamil each increased by 1.5-fold. Verapamil time to Cmax (Tmax) was increased by 1.2 hours.(2) Moderate and weak CYP3A4 inhibitors linked to this monograph include: amlodipine, anamorelin, aprepitant, avacopan, azithromycin, berberine, berotralstat, bicalutamide, blueberry, brodalumab, camizestrant, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clofazimine, conivaptan, crizotinib, daclatasvir, daridorexant, delavirdine, diltiazem, diosmin, elinzanetant, estrogen, flibanserin, fluvoxamine, fosaprepitant, fosnetupitant, fostamatinib, ginkgo, givinostat, glecaprevir/pibrentasvir, gepotidacin, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lazertinib, oral lefamulin, lenacapavir, levamlodipine, linagliptin, lomitapide, lumateperone, lurasidone, mavorixafor, netupitant, nicardipine, omeprazole, osilodrostat, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, resveratrol, rimegepant, roxithromycin, scutellarin, sevabertinib, simeprevir, sitaxsentan, stiripentol, ticagrelor, tofisopam, tolvaptan, trofinetide, vonoprazan, and voxelotor.(3,4)

Theophylline Derivatives/Lithium

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

MECHANISM OF ACTION: Theophylline derivatives increase the renal excretion of lithium.

CLINICAL EFFECTS: Decreased levels of lithium which may result in decreased clinical effectiveness.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Lithium levels and response should be monitored in patients in whom theophylline therapy is initiated or withdrawn. Patients receiving concurrent therapy should be monitored for increased adverse effects.

DISCUSSION: In a study involving ten volunteers, the concurrent administration of lithium and theophylline resulted in a significant decrease in lithium serum levels. Upon discontinuation of theophylline, lithium levels and half-life increased, and the clearance of lithium decreased. Individual variability in these parameters was significant. The overall incidence of adverse effects was significantly greater with concurrent therapy including restlessness, tremor, and anorexia. In another study in ten normal subjects, lithium (1200 mg/day for seven days) was administered and it was reported that theophylline infusion (dosed to achieve a plasma level of 14 mcg/ml) increased lithium clearances by 51%. In a case report, reduced lithium levels as well as worsening of manic symptoms occurred after increasing doses of theophylline were administered. It has been shown that aminophylline increases the lithium/creatinine clearance ratio, which may result in decreased serum lithium below the therapeutic level. Caffeine withdrawal has been reported to increase lithium levels in several case reports. This interaction is most important to consider in patients who have been previously sensitive to relapse with decreased lithium levels and in whom levels are maintained at the therapeutic/prophylactic borderline.

Weak Cyp3a4 Inhibitors/Lemborexant (<= 5 MG)

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

MECHANISM OF ACTION: Inhibitors of CYP3A4 may inhibit the metabolism of lemborexant.(1)

CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP3A4 may result in increased levels of and effects from lemborexant, including somnolence, fatigue, CNS depressant effects, daytime impairment, headache, and nightmare or abnormal dreams.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The maximum recommended dose of lemborexant with concurrent use of a weak CYP3A4 inhibitors should not exceed 5 mg per dose.(1) For patients on avapritinib: this interaction applies only to gastrointestinal stromal tumor (GIST) patients on avapritinib 200 mg or 300 mg.(2)

DISCUSSION: Lemborexant is a CYP3A4 substrate. In a PKPB model, concurrent use of lemborexant with itraconazole increased area-under-curve (AUC) and concentration maximum (Cmax) by 3.75-fold and 1.5-fold, respectively. Concurrent use of lemborexant with fluconazole increased AUC and Cmax by 4.25-fold and 1.75-fold, respectively.(1) Weak inhibitors of CYP3A4 include: amiodarone, amlodipine, anamorelin, asciminib, avapritinib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, camizestrant, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, vepdegestrant, viloxazine, vonoprazan, and ziftomenib.(1,3)

Weak Cyp3a4 Inhibitors/Mavacamten

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

MECHANISM OF ACTION: Weak CYP3A4 inhibitors may decrease the metabolism of mavacamten.(1)

CLINICAL EFFECTS: Concurrent use of weak CYP3A4 inhibitors may increase the plasma levels and the incidence and severity of adverse reactions of mavacamten.(1)

PREDISPOSING FACTORS: CYP2C19 poor metabolizers may experience an increased incidence or severity of adverse effects.(1)

PATIENT MANAGEMENT: The UK manufacturer of mavacamten states no dose adjustment is necessary when starting mavacamten in patients on weak CYP3A4 inhibitors or in intermediate, normal, rapid, or ultra-rapid CYP2C19 metabolizers already on mavacamten and starting a weak CYP3A4 inhibitor. In poor CYP2C19 metabolizers already on mavacamten and starting a weak CYP3A4 inhibitor, reduce mavacamten 5 mg to 2.5 mg or if on 2.5 mg pause treatment for 4 weeks. If CYP2C19 phenotype is unknown, consider a mavacamten starting dose of 2.5 mg daily.(1) For patients on avapritinib: this interaction applies only to gastrointestinal stromal tumor (GIST) patients on avapritinib 200 mg or 300 mg.(2)

DISCUSSION: In a PBPK model, concomitant use of mavacamten (15 mg daily) with cimetidine 400 mg twice daily, a weak CYP3A4 inhibitor, was predicted to increase mavacamten area-under-curve (AUC) by 6% and maximum concentration (Cmax) by 4% in poor CYP2C19 metabolizers and by 3% and 2%, respectively, in both intermediate and normal CYP2C19 metabolizers.(3) Weak CYP3A4 inhibitors include: amiodarone, amlodipine, anamorelin, asciminib, avapritinib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, chlorzoxazone, cilostazol, clotrimazole, cranberry, cyclosporine, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, istradefylline, ivacaftor, lacidipine, lapatinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, pazopanib, peppermint oil, propiverine, propofol, ranitidine, resveratrol, roxithromycin, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, vepdegestrant, and viloxazine. (4,5)

Weak Cyp3a4 Inhibitors/Ubrogepant (<= 50 MG)

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

MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of ubrogepant.(1)

CLINICAL EFFECTS: Concurrent use of ubrogepant with weak CYP3A4 inhibitors may result in an increase in exposure of ubrogepant.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when used concomitantly with weak CYP3A4 inhibitors. Initial dose of ubrogepant should not exceed 50 mg when used concomitantly with weak inhibitors of CYP3A4. A second dose may be given within 24 hours but should not exceed 50 mg when used concurrently with weak CYP3A4 inhibitors.(1) For patients on avapritinib: this interaction applies only to gastrointestinal stromal tumor (GIST) patients on avapritinib 200 mg or 300 mg.(2)

DISCUSSION: Coadministration of ubrogepant with verapamil, a moderate CYP3A4 inhibitor, resulted in a 3.5-fold and 2.8-fold increase in area-under-curve (AUC) and concentration maximum (Cmax), respectively. No dedicated drug interaction study was conducted to assess concomitant use with weak CYP3A4 inhibitors. The conservative prediction of the maximal potential increase in ubrogepant exposure with weak CYP3A4 inhibitors is not expected to be more than 2-fold.(1) Weak inhibitors of CYP3A4 include: amiodarone, amlodipine, anamorelin, asciminib, avapritinib, azithromycin, Baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, camizestrant, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, delavirdine, deutivacaftor, dihydroberberine, diosmin, elinzanetant, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, maribavir, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, pirtobrutinib, propiverine, propofol, ranitidine, ranolazine, resveratrol, roxithromycin, simeprevir, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, vepdegestrant, viloxazine, vonoprazan, and ziftomenib.(3,4)

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• Biliary obstruction

• Biliary calculus
• Insomnia

• Anxiety disorder
• Disease of liver
• Hypertension

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Rare or Very Rare

• Hypersensitivity drug reaction

Rare or Very Rare

• Acute abdominal pain
• Alopecia
• Headache disorder
• Pain in oropharynx
• Pharyngitis
• Skin rash

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