Menopause Support (vit B complex/vit E acet/folic acid/minerals no.35/soybean)
Vitamin B Complex Oral Tablet
Last reviewed · Source: First Databank (FDB) drug data
Overview
Folic acid is a water-soluble, B complex vitamin.
Folic acid is used for the treatment of megaloblastic and macrocytic anemias resulting from folate deficiency. The drug is usually indicated in the treatment of nutritional macrocytic anemia; megaloblastic anemias of pregnancy, infancy, and childhood; and megaloblastic anemia associated with primary liver disease, alcoholism and alcoholic cirrhosis, intestinal strictures, anastomoses, or sprue. Folate deficiency may also result from increased loss of folate secondary to renal dialysis or the administration of some drugs such as phenytoin, primidone, barbiturates, methotrexate, nitrofurantoin, or sulfasalazine.
Generic name: vit B complex/vit E acet/folic acid/minerals no.35/soybean
Drug class: Vitamin B Complex
Therapeutic class: Alternative Therapy
Reference product & biosimilars
No reference, biosimilar or interchangeable associated with this drug.
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Indications
No indications are available for this drug.
Dosing
Dosage of folic acid injection (sodium folate) is expressed in terms of folic acid. In general, although patient response to folic acid therapy depends on the degree and nature of the deficiency, once proper corrective measures are undertaken, folate-deficient patients generally respond rapidly. During the first 24 hours of treatment, the patient experiences an improved sense of well-being, and within 48 hours, the bone marrow begins to become normoblastic. Reticulocytosis generally begins within 2-5 days following initiation of folic acid therapy.
Folic acid is usually administered orally. When oral administration is not feasible or when malabsorption is suspected, the drug may be administered by deep IM, subcutaneous, or IV injection. However, most patients with malabsorption are able to absorb oral folic acid.
No dosing information is available for this tab.
No dosing information is available for this tab.
Drug interactions
In folate-deficient patients, folic acid therapy may increase phenytoin metabolism, resulting in decreased phenytoin serum concentrations. Although this interaction is not usually clinically important, an increase in seizure frequency may occur in some patients.
It has been reported that concurrent administration of chloramphenicol and folic acid in folate-deficient patients may result in antagonism of the hematopoietic response to folic acid. Although the importance and mechanism of the interaction is unclear, the hematologic response to folic acid in patients receiving both drugs should be carefully monitored.
Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.
Amylase; Pancreatin/Acarbose; Miglitol
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: Digestive enzyme preparations such as amylase or pancreatin may break down acarbose(1) and miglitol.(2)
CLINICAL EFFECTS: The concurrent administration digestive enzyme preparations such as amylase or pancreatin may decrease the effectiveness of acarbose(1) and miglitol.(2)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The manufacturer of acarbose states that digestive enzymes such as amylase or pancreatin should not be taken concomitantly with acarbose.(1) The manufacturer of miglitol states that digestive enzymes such as amylase or pancreatin should not be taken concomitantly with miglitol.(2)
DISCUSSION: Because digestive enzyme preparations such as amylase or pancreatin may break down acarbose(1) and miglitol(2) and decrease their effectiveness, the manufacturer of acarbose(1) and miglitol(2) state they should not be taken concomitantly with these agents.
Antacids/Olverembatinib
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 aqueous solubility of olverembatinib is pH dependent. Higher gastric pH leads to lower solubility which may reduce olverembatinib absorption.(1)
CLINICAL EFFECTS: Coadministration of antacids may reduce the bioavailability of olverembatinib leading to decreased systemic levels and effectiveness.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The manufacturer of olverembatinib states that concurrent use with antacids should be avoided.(1)
DISCUSSION: Olverembatinib has pH-dependent solubility.(1)
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)
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.
Alum;Ca;Mag/Oral Phosphate Supplements; Urinary Ph Modifiers
SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
MECHANISM OF ACTION: Medications containing significant amounts of aluminum, calcium, or magnesium may bind to the phosphate and prevent its absorption.(1)
CLINICAL EFFECTS: Concurrent use of medications containing significant amounts of aluminum, calcium, or magnesium may result in decreased effectiveness of phosphate supplements and urinary pH modifiers high in phosphate.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Patients receiving phosphate supplements or urinary pH modifiers high in phosphate should be instructed to avoid medications containing aluminum, calcium, or magnesium.(1) If concurrent use cannot be avoided, separate the administration of phosphate containing products by as much time as possible from medications containing aluminum, calcium, or magnesium. Some phosphate laxative products used as phosphate supplements may contain sufficient quantities of phosphate to interact as well.
DISCUSSION: The manufacturer of K-Phos states that products containing aluminum, calcium, or magnesium may bind to the phosphate and prevent its absorption. Therefore, patients receiving phosphate supplements and urinary pH modifiers high in phosphate should be instructed to avoid products containing aluminum, calcium, or magnesium.(1)
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.
Antacids/Selected Mesalamine
SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
MECHANISM OF ACTION: Certain mesalamine formulations (namely Apriso) contain granules with an enteric coating that dissolves at pH 6 and above. Antacids may raise the intragastric pH, resulting in premature release of the drug in the stomach.(1)
CLINICAL EFFECTS: Simultaneous administration of certain mesalamine formulations (namely Apriso) with an antacid may result in premature release of mesalamine in the stomach and decreased effectiveness in the intestines and colon.(1-2)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The manufacturer of Apriso states that coadministration with antacids should be avoided.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: Dissolution of the enteric coating of mesalamine is pH-dependent. Coadministration of certain mesalamine formulations (namely Apriso) with antacids should be avoided.(1)
Antacids/Ziftomenib
SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
MECHANISM OF ACTION: The aqueous solubility of ziftomenib is pH dependent. Higher gastric pH leads to lower solubility which may reduce ziftomenib absorption.(1)
CLINICAL EFFECTS: Coadministration with antacids may reduce the bioavailability of ziftomenib, leading to decreased systemic levels and effectiveness.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The manufacturer of ziftomenib states that concurrent use with antacids should be avoided.(1) If concurrent use cannot be avoided, administer ziftomenib 2 hours before or 2 hours after the administration of an antacid.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: The impact of antacids on the pharmacokinetics of ziftomenib has not been investigated in clinical studies. In an interaction study, coadministration of proton pump inhibitors (PPIs) decreased ziftomenib area-under-the-curve (AUC) by 53% and maximum concentration (Cmax) by 70%.(1)
Calcium Carbonate/Raltegravir (600 MG HD)
SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
MECHANISM OF ACTION: Calcium carbonate may alter raltegravir absorption by altering gastric pH and binding to raltegravir in the GI tract, preventing its absorption.(1)
CLINICAL EFFECTS: Calcium carbonate may reduce levels and clinical effectiveness of raltegravir.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Calcium carbonate is not recommended for patients receiving one daily raltegravir (600 mg HD tablets).(1)
DISCUSSION: Simultaneous administration of calcium carbonate (3000 mg) with raltegravir (1200 mg singe dose given as two 600 mg HD tablets) decreased raltegravir maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) by 74%, 72%, and 48%, respectively.(1,2) Administration of calcium carbonate (3000 mg) 12 hours after raltegravir (1200 mg singe dose given as two 600 mg HD tablets) decreased raltegravir Cmax, AUC, and Cmin by 2%, 10%, and 57%, respectively.(1,2) Data from in vitro(3) and in vivo simulations(4) suggest that magnesium's effect on raltegravir may involve chelation as well as changes in pH. Calcium may have a similar effect.
Folic Acid/Fluorouracil & Fluorouracil Prodrugs
SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
MECHANISM OF ACTION: Folic acid has been shown to enhance both the therapeutic and toxic effects of fluoropyrimidines, such as 5-fluorouracil (5-FU) and fluorouracil prodrugs.(1-3) Fluorouracil prodrugs include capecitabine and tegafur.
CLINICAL EFFECTS: Folic acid, when used concurrently with 5-FU or fluorouracil prodrugs, has been shown to increase side effects of 5-FU.(1-3)
PREDISPOSING FACTORS: Patients who are intermediate or poor dihydropyrimidine dehydrogenase (DPYD) metabolizers have diminished or no DPYD function. Since DPYD is the rate-limiting enzyme involved in fluoropyrimidine metabolism, these patients may be more susceptible to the effects of this interaction.(3)
PATIENT MANAGEMENT: Folic acid or folate analog-containing products should not be used concurrently with fluorouracil or fluorouracil prodrugs unless directed by the healthcare provider.(1-3) Fluorouracil prodrugs include capecitabine and tegafur.
DISCUSSION: Due to increased toxic effects, stomatitis and diarrhea are observed more commonly, may be more severe, and may occur for a prolonged duration when compared to therapy with 5-FU alone. It is postulated that the lower standard dose of 5-FU in the US versus other regions may be due to increased folic acid supplementation within the US food supply.(2) In a cohort study in 290 patients, the use of dietary supplements with folic acid during treatment compared to nonuse increased the risk of capecitabine toxicities (HR 1.81, 95%CI: 1.15,2.85). The detection of folic acid in plasma also increased the risk of capecitabine toxicities (HR 2.09, 95%CI: 1.24,3.52 and HR 2.31, 95%CI: 1.29,4.13 at diagnosis and during treatment, respectively).(4) In a cohort study of 9 patients, patients taking folate-containing supplements and higher serum folate levels had an increased risk of grade >=2 toxicity. The risk of grade >=2 toxicity increased by 9% for every increase in serum folate level by 10 nmol/L. Patients with grade >=2 toxicity had higher serum folate levels than patients with grade <= 1 toxicity (28 nmol/L [range, 13.2-45.4] vs. 20 nmol/L [range, 12.8-45.4]; p=0.001).(5) In two case reports, patients developed capecitabine toxicity while taking supplements containing folic acid 400-500 mcg.(6) In a case report, a woman developed grade 4 diarrhea, grade 3 vomiting, and grade 3 hand-foot syndrome 8 days after the addition of capecitabine (2500 mg/m2/day) to high-dose folic acid supplementation. She developed necrotic colitis and died, despite the discontinuation of folic acid and capecitabine.(7) There are two other reports of excessive fluorouracil toxicity in patients treated with folic acid.(8)
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)
Serum Phosphate Level-Altering Drugs/Erdafitinib
SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.
MECHANISM OF ACTION: Medications that alter serum phosphate may interfere with interpretation of phosphate levels that are needed to determine initial erdafitinib dose.(1)
CLINICAL EFFECTS: Serum phosphate levels that are elevated by concomitant medications may result in an inappropriately low dose and decreased effectiveness of erdafitinib. Serum phosphate levels that are decreased by concomitant medications may result in an inappropriately high dose and increased toxicity from erdafitinib.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The manufacturer of erdafitinib states that agents that alter serum phosphate levels should be avoided before the initial dose increase period for erdafitinib based on serum phosphate levels (days 14 to 21).(1)
DISCUSSION: Concomitant administration of serum phosphate level-altering agents during the initial dose increase period of erdafitinib based on serum phosphate levels (days 14 to 21) may interfere with serum phospate levels and lead to incorrect dosing of erdafitinib.(1) Agents that may alter serum phosphate levels linked to this monograph include: aluminum carbonate, aluminum hydroxide, calcium acetate, calcium carbonate, calcium citrate, cod liver oil, ferric citrate, lanthanum, magnesium carbonate, magnesium hydroxide, potassium phosphate, sevelamer, sodium phosphate, sucroferric oxyhydroxide, tenapanor, and vitamin D.(1)
Moderate Interaction: Assess the risk to the patient and take action as needed.
Agents Affecting Gastric Ph/Itraconazole; Ketoconazole
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Antacids, buffers in didanosine products, H2 antagonists, and proton-pump inhibitors increase the stomach pH. Quinapril tablets may contain a high percentage of magnesium. Since some orally administered azole antifungal agents require an acidic medium for optimal absorption, agents may decrease the absorption of azole antifungal agents.
CLINICAL EFFECTS: Simultaneous administration of an antacid, buffered didanosine, a H2 antagonist, or a proton-pump inhibitor may result in decreased therapeutic effects of the azole antifungal.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: If the concurrent administration of these two agents cannot be avoided, consider administering two capsules of glutamic acid hydrochloride 15 minutes before administering the antifungal and separate the administration times of the antifungal and the agent affecting gastric pH by at least two hours.
DISCUSSION: Itraconazole, ketoconazole, and posaconazole require an acidic medium for predictable dissolution and absorption decreases as pH increases and proton pump inhibitors are expected to decrease their absorption.(1-4) In a study in 11 healthy subjects, omeprazole (40 mg daily) decreased the maximum concentration (Cmax) and area-under-curve (AUC) of itraconazole (200 mg single dose) by 66% and 64%, respectively.(5) In a study in 15 healthy subjects, omeprazole (40 mg daily) had no effect on the pharmacokinetics of itraconazole solution.(6) In a study in 9 healthy subjects, omeprazole (60 mg) decreased the AUC of ketoconazole (200 mg single dose) by 83.4% compared to control (ketoconazole alone). Administration of Coca-Cola (240 ml) with ketoconazole and omeprazole raised ketoconazole AUC to 65% of control values.(7) Omeprazole has been shown to have no significant effect on the absorption of fluconazole(8) or voriconazole.(9) Case reports and in-vivo studies have documented significant decreases in ketoconazole levels during concurrent therapy with H-2 antagonists, including cimetidine and ranitidine. Concurrent administration of itraconazole and famotidine resulted in a significant decrease in itraconazole levels, but no significant changes in famotidine levels. An interaction should be expected to occur between both ketoconazole or itraconazole and the other H-2 antagonists.(10-14) In randomized, open-labeled, cross-over study in 12 healthy subjects, simultaneous administration of an antacid decreased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of itraconazole (200 mg) by 66% and 70%, respectively. Time to Cmax (Tmax) increased by 70%.(15) This interaction has also been reported in a case report.(16) In a study in 3 subjects, simultaneous administration of a combination aluminum hydroxide/magnesium hydroxide (30 ml) decreased the AUC of a single dose of ketoconazole (200 mg) by 41%.(172) In a case report, a patient receiving concurrent ketoconazole with aluminum hydroxide, cimetidine, and sodium bicarbonate did not respond to therapy until cimetidine was discontinued and the administration time of aluminum hydroxide and cimetidine was changed to 2 hours after ketoconazole. In a follow-up study in 2 subjects, concurrent cimetidine and sodium hydroxide lowered ketoconazole levels.(18) In a study in 14 subjects, simultaneous administration of aluminum hydroxide/magnesium hydroxide (20 ml, 1800 mg/1200 mg) had no significant effects on fluconazole pharmacokinetics.(3) In a randomized, open-label, cross-over study in 6 subjects, simultaneous administration of itraconazole with buffered didanosine tablets resulted in undetectable levels of itraconazole.(19) In a randomized cross-over study in 12 HIV-positive subjects, administration of buffered didanosine tablets 2 hours after ketoconazole had no effects on ketoconazole levels.(20) In a randomized, cross-over, open-label study in 24 healthy subjects, simultaneous administration of enteric-coated didanosine had no effect on ketoconazole pharmacokinetics.(21) One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.
Aluminum-Magnesium Hydroxide; Oral Calcium/Phenytoin
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Aluminum hydroxide; magnesium hydroxide, and oral calcium may bind to phenytoin, preventing its absorption.(1-4)
CLINICAL EFFECTS: Simultaneous ingestion of aluminum-magnesium hydroxide and/or calcium-containing products may result in decreased levels and effectiveness of phenytoin.(1-4)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The US manufacturer of phenytoin recommends that administration times of phenytoin and antacids being staggered.(1)
DISCUSSION: In a study in 8 healthy subjects, simultaneous administration of phenytoin (600 mg) with calcium carbonate significantly decreased the area-under-curve (AUC) of phenytoin.(2) In a study in 8 healthy subjects, simultaneous administration of aluminum-magnesium hydroxide or calcium carbonate significantly decreased the AUC of phenytoin.(3) In a study in 6 patients with epilepsy, concurrent administration of an aluminum-magnesium hydroxide antacid resulted in a small but statistically significant decrease in phenytoin AUC.(4)
Antacids And Selected Minerals/Oral Iron Supplements
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Some antacids may bind to iron, preventing its absorption. Alterations in gastric pH by antacids may also play a role. Iron may bind to other minerals such as calcium, manganese, tin, and zinc in the GI tract.
CLINICAL EFFECTS: Simultaneous administration of an antacid or minerals may decrease the absorption of orally administered iron.
PREDISPOSING FACTORS: The interaction with some combinations may be affected by the presence or absence of food.
PATIENT MANAGEMENT: Iron supplements should not be taken within 1 hour before or 2 hours after antacids, calcium, manganese, or zinc.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: Magnesium hydroxide has been shown to inhibit the absorption of elemental iron,(2) although other studies have shown conflicting results.(3,4) Sodium bicarbonate has been shown to decrease the absorption of iron by 50%.(3) In a study in 61 healthy subjects, calcium citrate, calcium carbonate, and calcium phosphate inhibited iron absorption when taken with food. However, in the fasted state, calcium carbonate had no effect on iron absorption. In the fasted state, calcium citrate and calcium phosphate decreased iron absorption by 49% and 62%, respectively,(6) In a study in 23 healthy subjects, calcium acetate and calcium carbonate decreased the area-under-curve (AUC) of elemental iron (65 mg) by 27% and 19%, respectively.(7) In a study, manganese decreased iron absorption. A ratio of 5:1 of zinc:iron decreased iron absorption by 56%.(8) In a study, inorganic iron decreased zinc absorption.(9) In another study, ferrous sulfate decreased the absorption of zinc sulfate in a concentration dependent manner; however, heme chloride had no effect on zinc sulfate.(10) In a study in premature infants, administration of liquid zinc and iron supplements between feedings decreased iron uptake; however, no effect was seen when the supplements were mixed with feedings.(11) One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.
Antacids/Cefpodoxime
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Absorption of oral cefpodoxime may be reduced in patients receiving concomitant treatment with acid reducing agents.(1-3)
CLINICAL EFFECTS: Antibiotic efficacy against organisms with a high minimum inhibitory concentration (MIC) to cefpodoxime could be decreased.
PREDISPOSING FACTORS: Taking cefpodoxime on an empty stomach magnifies this effect.
PATIENT MANAGEMENT: Separate the administration of cefpodoxime by at least 1-2 hours after administration of antacids. Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. Since concurrent use of H2 antagonists and proton pump inhibitors (PPIs) in patients taking cefpodoxime should be avoided, these would not be alternatives to antacids in these patients.
DISCUSSION: In a study of ten subjects, administration of cefpodoxime after single dose famotidine 40 mg decreased both maximum concentration (Cmax) and area-under-curve (AUC) by approximately 40% compared with administration of cefpodoxime on an empty stomach.(2) In a study of 17 subjects, administration of cefpodoxime after single dose ranitidine 150 mg decreased Cmax and AUC by approximately 40% compared with administration of cefpodoxime on an empty stomach.(3)
Antacids/Defactinib
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The aqueous solubility of defactinib is pH dependent. Higher gastric pH leads to lower solubility which may reduce defactinib absorption.(1)
CLINICAL EFFECTS: Coadministration with antacids may reduce the bioavailability of defactinib, leading to decreased systemic levels and effectiveness.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The manufacturer of defactinib states that patients requiring acid-lowering therapy should separate defactinib from antacid administration by 2 hours.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: The impact of antacids on the pharmacokinetics of defactinib has not been investigated in clinical studies. In an interaction study, defactinib area-under-the-curve (AUC) decreased by 79% and maximum concentration (Cmax) decreased by 85% following concomitant use of multiple doses of omeprazole 40 mg daily. The AUC and Cmax of N-desmethyl amide (M4), a major active metabolite of defactinib, decreased by 83% and 88%, respectively.(1)
Antacids/Delavirdine
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The exact mechanism is unknown. Antacids decrease the absorption of delavirdine.(1)
CLINICAL EFFECTS: The simultaneous administration of delavirdine with an antacid may decrease the absorption of delavirdine, which may result in subtherapeutic levels.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The administration of delavirdine and antacids should be separated by at least one hour.(1) Some vitamin preparations may contain sufficient quantities of magnesium salts with antacid properties to interact as well.
DISCUSSION: In a single dose study in 12 healthy subjects, the simultaneous administration of delavirdine with an alumina and magnesia oral suspension (20 ml) decreased the delavirdine area-under-curve (AUC) and maximum concentration (Cmax) by 44% and 52%, respectively.(1)
Antacids/Infigratinib; Selpercatinib
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The solubility of infigratinib and selpercatinib is pH dependent. Antacid-induced changes in gastric pH may decrease the absorption of infigratinib and selpercatinib.(1,2)
CLINICAL EFFECTS: Simultaneous administration of antacids may result in decreased levels and effectiveness of infigratinib and selpercatinib.(1,2)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Avoid the use of antacids, proton pump inhibitors (PPIs), and H2 antagonists, in patients receiving treatment with infigratinib or selpercatinib. If coadministration with antacids cannot be avoided, take infigratinib or selpercatinib at least 2 hours before or 2 hours after the antacid.(1,2) If the antacid is replaced with a H2 antagonist, take infigratinib or selpercatinib 2 hours before or 10 hours after the H2 antagonist.(1,2) If the antacid is replaced with a PPI, take selpercatinib with food.(2)
DISCUSSION: Infigratinib is practically insoluble at pH 6.8.(1) Selpercatinib solubility is pH dependent.(2) Antacids may decrease the solubility and absorption of infigratinib and selpercatinib and decrease their effectiveness.
Antacids/Levoketoconazole
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The aqueous solubility of levoketoconazole is pH dependent. Higher gastric pH leads to lower solubility. Antacids increase gastric pH and may decrease the absorption of levoketoconazole.(1)
CLINICAL EFFECTS: Coadministration of antacids may reduce the bioavailability of levoketoconazole, leading to decreased systemic levels and effectiveness.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Coadministration of levoketoconazole with proton pump inhibitors and H2 antagonists should be avoided. If coadministration with an acid-reducing agent is unavoidable, take the antacid 2 hours before levoketoconazole.(1)
DISCUSSION: Levoketoconazole is very slightly soluble in water but soluble below pH 2. Antacids raise gastric pH and may impair dissolution and absorption of levoketoconazole.(1)
Antacids/Nirogacestat
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The aqueous solubility of nirogacestat is pH dependent. Higher gastric pH leads to lower solubility which may reduce nirogacestat absorption.(1)
CLINICAL EFFECTS: Coadministration of antacids may reduce the bioavailability of nirogacestat, leading to decreased systemic levels and effectiveness.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Coadministration of nirogacestat with proton pump inhibitors, H2 antagonists, and antacids should be avoided. If coadministration with an acid-reducing agent is unavoidable, take nirogacestat 2 hours before or 2 hours after a locally acting antacid.(1)
DISCUSSION: The solubility of nirogacestat is poor at a pH >= 6.(1) Concomitant use of proton pump inhibitors, H2 antagonists, or antacids are expected to reduce concentrations of nirogacestat.(1)
Antacids/Pritelivir
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The aqueous solubility of pritelivir is pH dependent. Higher gastric pH leads to lower solubility which may reduce pritelivir absorption.(1)
CLINICAL EFFECTS: Coadministration of antacids may reduce the bioavailability of pritelivir, leading to decreased systemic levels and effectiveness.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Take pritelivir at least 2 hours before or 2 hours after antacids.(1)
DISCUSSION: The combination of pritelivir with antacids has not been studied. Pritelivir absorption is pH-dependent.(1) Coadministration of a single oral dose of 100 mg pritelivir (on Day 1) with esomeprazole 40 mg once daily (from day -3 to Day 1; 4 days total) decreased pritelivir's maximum concentration (Cmax) by 76% and area-under-curve (AUC) by 59% compared to pritelivir administered alone.(1)
Antacids/Ravidasvir
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Absorption of ravidasvir may be reduced in patients receiving concomitant treatment with acid reducing agents.(1)
CLINICAL EFFECTS: Administration of antacids may reduce the bioavailability of ravidasvir, leading to decreased systemic levels and effectiveness.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: In order to assure systemic absorption and maximal effectiveness from use of this Hepatitis C treatment, counsel patient to separate ravidasvir from antacid administration by 4 hours.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: Interaction studies with antacids have not been performed. Co-administration with antacids are expected to decrease ravidasvir plasma concentrations and potentially result in Hepatitis C treatment failure.(1)
Antacids/Rilzabrutinib
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Rilzabrutinib solubility decreases with increasing pH. Antacid induced increase in gastric pH may result in a decrease in rilzabrutinib absorption.(1)
CLINICAL EFFECTS: Simultaneous administration of an antacid may result in decreased levels and effectiveness of rilzabrutinib.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Administer rilzabrutinib at least 2 hours before taking antacids.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: The impact of antacids on the pharmacokinetics of rilzabrutinib has not been investigated in clinical studies. In an interaction study, administration of famotidine (H2 receptor antagonist) two hours after the evening dose of rilzabrutinib decreased the next morning dose of rilzabrutinib maximum concentration (Cmax) by 35% and area-under-curve (AUC) by 28%.(1) In another interaction study, coadministration of esomeprazole decreased rilzabrutinib Cmax by 55% and AUC by 51%.(1)
Antacids/Riociguat
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The mechanism of interaction is not clear. Increased gastric pH is thought to decrease riociguat solubility and absorption.(1)
CLINICAL EFFECTS: Simultaneous administration of riociguat with an antacid may result in decreased levels and effectiveness of riociguat.(1-2)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Separate the administration of antacids and riociguat by at least 1 hour.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: Administration of 10 mL of an aluminum hydroxide-magnesium hydroxide containing antacid decreased the area-under-curve (AUC)and maximum concentration (Cmax)of riociguat by 34% and 56% respectively.(1)
Antacids/Selected Cephalosporins
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Absorption of oral cefuroxime may be reduced in patients receiving concomitant treatment with acid reducing agents.(1,2)
CLINICAL EFFECTS: Antibiotic efficacy against organisms with a high minimum inhibitory concentration (MIC) to cefuroxime could be decreased.
PREDISPOSING FACTORS: Taking cefuroxime on an empty stomach magnifies this effect.
PATIENT MANAGEMENT: Separate the administration of cefuroxime by at least 1-2 hours after administration of antacids. Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. Since concurrent use of H2 antagonists and proton pump inhibitors (PPIs) in patients taking cefuroxime should be avoided, these would not be alternatives to antacids in these patients.
DISCUSSION: In a study performed prior to the introduction of PPIs, administration of ranitidine 300 mg and sodium bicarbonate followed by cefuroxime taken on a empty stomach lowered both Cmax and AUC of cefuroxime by approximately 40 per cent compared with administration of cefuroxime alone on an empty stomach. Postprandial administration of cefuroxime in subjects taking ranitidine was similar to that of subjects taking cefuroxime on an empty stomach.(2)
Antacids/Selected Kinase Inhibitors
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The solubility of bosutinib,(1) dasatinib,(2) erlotinib,(3) gefitinib,(4) neratinib,(5) nilotinib(6), pazopanib,(7) and pexidartinib(8) is pH dependent. Antacid-induced changes in gastric pH may decrease the absorption of these agents.(1-8)
CLINICAL EFFECTS: Simultaneous administration of antacids may result in decreased levels and effectiveness of bosutinib,(1) dasatinib,(2) erlotinib,(3) gefitinib,(4) neratinib,(5) nilotinib(6), pazopanib,(7) and pexidartinib.(8)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Antacid use should be considered in place of H2 blockers or proton pump inhibitors in patients receiving bosutinib,(1) dasatinib,(2) erlotinib,(3) gefitinib,(4) neratinib,(5) nilotinib(6), pazopanib,(7) and pexidartinib;(8) however, separation of administration times is required. If antacids are used, separate the administration times by several hours(1-8) but at least 2 hours for bosutinib,(1) dasatinib,(2) nilotinib,(6) and pexidartinib(8), 6 hours for gefitinib,(4) and 3 hours for neratinib.(5) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: In a study in 24 healthy subjects, lansoprazole (60 mg) decreased bosutinib (400 mg single dose) area-under-curve (AUC) and maximum concentration (Cmax) by 26% and 46%, respectively.(1) In a study in 24 healthy subjects, simultaneous administration of dasatinib (50 mg) with aluminum hydroxide/magnesium hydroxide (30 ml) decreased dasatinib AUC and Cmax by 55% and 58%, respectively. In the same subjects, administration of the antacid 2 hours before dasatinib decreased dasatinib Cmax by 26%, but had no effect on dasatinib AUC.(2) In a study in 24 healthy subjects, administration of a single dose of dasatinib (50 mg) 10 hours after famotidine decreased dasatinib AUC and Cmax by 61% and 63%, respectively.(2) In a study, concurrent omeprazole decreased the AUC and Cmax of erlotinib by 46% and 61%, respectively.3) In a study, concurrent esomeprazole decreased the AUC of nilotinib by 34%.(6) In a study in 15 healthy subjects, lansoprazole (30 mg at steady state) decreased the Cmax and AUC of a single dose of neratinib (240 mg) by 71% and 65%, respectively.(5) There were no significant changes in nilotinib pharmacokinetics when famotidine was administered 10 hours before or 2 hours after nilotinib.(6) There were no significant changes in nilotinib pharmacokinetics when an antacid (aluminum hydroxide/magnesium hydroxide/simethicone) was administered 2 hours before or after nilotinib.(6) Coadministration of esomeprazole decreased pexidartinib Cmax and AUC by 55% and 50%, respectively.(8)
Antacids/Sotorasib
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The aqueous solubility of sotorasib is pH dependent. Higher gastric pH leads to lower solubility which may reduce sotorasib absorption.(1)
CLINICAL EFFECTS: Coadministration of antacids may reduce the bioavailability of sotorasib, leading to decreased systemic levels and effectiveness.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Coadministration of sotorasib with proton pump inhibitors, H2 antagonists, and antacids should be avoided. If coadministration with an acid-reducing agent is unavoidable, take sotorasib 4 hours before or 10 hours after a locally acting antacid.(1)
DISCUSSION: The solubility of sotorasib in the aqueous media decreases over the range pH 1.2 to 6.8 from 1.3 mg/mL to 0.03 mg/mL. In an interaction study, coadministration of repeat doses of omeprazole with a single dose of sotorasib decreased sotorasib maximum concentration (Cmax) by 65% and area-under-curve (AUC) by 57% under fed conditions, and decreased sotorasib Cmax by 57% and AUC by 42% under fasted conditions. Coadministration of a single dose of famotidine given 10 hours prior to and 2 hours after a single dose of sotorasib under fed conditions decreased sotorasib Cmax by 35% and AUC by 38%.(1)
Antacids/Taletrectinib
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The aqueous solubility of taletrectinib is pH dependent. Higher gastric pH leads to lower solubility which may reduce taletrectinib absorption.(1)
CLINICAL EFFECTS: Coadministration with antacids may reduce the bioavailability of taletrectinib, leading to decreased systemic levels and effectiveness.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The manufacturer of taletrectinib states that patients requiring acid-lowering therapy should separate taletrectinib from antacid administration by 2 hours.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: The impact of antacids on the pharmacokinetics of taletrectinib has not been investigated in clinical studies. In an interaction study, taletrectinib area-under-the-curve (AUC) decreased by 40% and maximum concentration (Cmax) decreased by 65% following concomitant use of omeprazole 40 mg daily.(1)
Antacids; Buffered Formulations/Amprenavir; Atazanavir
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Antacids increase gastric pH. As gastric pH increases, the solubility of atazanavir decreases.(1,2) The exact mechanism behind the interaction between amprenavir and antacids is unknown.(3)
CLINICAL EFFECTS: Simultaneous administration of amprenavir or atazanavir with antacids or buffered formulations may result in decreased levels and effectiveness of amprenavir(3) and atazanavir.(1,2)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The manufacturer of amprenavir states that amprenavir should be administered 1 hour before or after antacids or buffered formulations such as didanosine.(3) The manufacturer of atazanavir states that atazanavir should be administered 2 hours before or 1 hour after antacids or buffered formulations.(1,2) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: Simultaneous administration of atazanavir with didanosine buffered tablets decreased atazanavir area-under-curve (AUC), maximum concentration (Cmax) and minimum concentration (Cmin) by 87%, 89% and 84%, respectively. Administration of atazanavir 1 hour after didanosine buffered tablets had no significant effect on atazanavir pharmacokinetics.(1) Other buffered formulations and antacids are expected to substantially decrease atazanavir concentrations and therapeutic effectiveness as well.(1,2)
Antacids; H2 Antagonists/Ledipasvir; Velpatasvir
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The aqueous solubility of ledipasvir and velpatasvir is pH dependent. Higher gastric pH leads to lower solubility which may reduce ledipasvir and velpatasvir's absorption.(1-3)
CLINICAL EFFECTS: Administration of antacids and H2 antagonists may reduce the bioavailability of ledipasvir and velpatasvir, leading to decreased systemic levels and effectiveness.(1-3)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: In order to assure systemic absorption and maximal effectiveness from use of this Hepatitis C treatment, counsel patient to separate products containing ledipasvir or velpatasvir from antacid administration by 4 hours.(1-3) H2 antagonists may be administered simultaneously or 12 hours apart from products containing ledipasvir or velpatasvir at a dose that does not exceed doses comparable to famotidine 40 mg twice daily (or a total daily dose comparable to famotidine 80 mg).(1-3) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: In an interaction study, famotidine 40 mg, given with or 12 hours after a ledipasvir-sofosbuvir dose did not have significant effects on ledipasvir-sofosbuvir exposure.(1) In an interaction study, famotidine 40 mg, given with or 12 hours prior to a velpatasvir-sofosbuvir dose did not have a significant effect on velpatasvir-sofosbuvir exposure.(2) In an interaction study, famotidine (dosage not stated) did not have a significant effect on the pharmacokinetic of sofosbuvir, velpatasvir, or voxilaprevir.(3)
Antacids; H2 Antagonists/Rilpivirine
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Rilpivirine requires an acidic medium for absorption. Antacid or H2 antagonist induced decrease in gastric pH may result in a decrease in rilpivirine absorption.(1)
CLINICAL EFFECTS: 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: In patients maintained on rilpivirine, administer antacids at least 2 hours before or 4 hours after rilpivirine.(1) In patients maintained on rilpivirine, administer H2 antagonists at least 12 hours before or 4 hours after rilpivirine.(1) Concurrent use of proton pump inhibitors with rilpivirine is contraindicated.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: In a study in 16 subjects, omeprazole (20 mg daily) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (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 after a single dose of rilpivirine (150 mg) increased the rilpivirine Cmax and AUC by 21% and 13%, respectively.(1)
Antacids; Selected H2 Antagonists/Acalabrutinib Capsules
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Acalabrutinib capsules solubility decreases with increasing pH. Antacid or H2 antagonist induced increase in gastric pH may result in a decrease in acalabrutinib capsules absorption.(1)
CLINICAL EFFECTS: Simultaneous administration of an antacid or a H2 antagonist may result in decreased levels and effectiveness of acalabrutinib capsules.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Separate administration of acalabrutinib capsules and antacids by at least 2 hours.(1) In patients on acalabrutinib capsules, administer acalabrutinib capsules at least 2 hours before taking H2 antagonists.(1) Concurrent use of proton pump inhibitors with acalabrutinib capsules is not recommended.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. Acalabrutinib tablets are not affected by coadministration with H2 antagonists or antacids, and may be used concurrently.(1)
DISCUSSION: In a study in healthy subjects, coadministration with an antacid (calcium carbonate 1 gram) decreased area-under-curve (AUC) of acalabrutinib capsules by 53%. Coadministration with a proton pump inhibitor (omeprazole 40 mg for 5 days) decreased AUC of acalabrutinib capsules by 43%.(1)
Antacids; Urinary Alkalinizers/Amphetamines
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Antacids and urinary alkalinizers increase the absorption of amphetamines.(1-3)
CLINICAL EFFECTS: Concurrent use of amphetamines and antacids or urinary alkalinizers may result in increased amphetamine levels and side effects.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The US and Canadian manufacturers state that coadministration of alkalinizing agents with amphetamines should be avoided.(1-3) The Canadian manufacturer states that concurrent use of proton pump inhibitors and amphetamines should be avoided.(3) The US manufacturer states that patients receiving concurrent therapy should be monitored for changes in clinical effects.(1) Monitor patients receiving concurrent therapy for changes in amphetamine effectiveness and side effects. If concurrent use cannot be avoided, separate the administration times of amphetamines and antacids. Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: Concurrent use of alkalinizing agents with amphetamines increase the absorption of amphetamines. Co-administration of these should be avoided because of the potential of increased actions of the amphetamines.(1,2)
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)
Calcium; Iron; Sucralfate/Thyroid Preparations
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The mechanism by which malabsorption of thyroid preparations occurs from calcium-containing products is presumed to be a binding of the medication to the thyroid hormone, forming an insoluble or nonabsorbable complex.(1-3) Iron may form a ferric-thyroxine complex with thyroid agents, preventing their absorption from the gastrointestinal tract.(1,4) Sucralfate binds to other agents in the gastrointestinal tract and alters absorption of other drugs, including thyroid agents.(1,5)
CLINICAL EFFECTS: The simultaneous administration of thyroid preparations with calcium, iron, or sucralfate may result in decreased levels and clinical effects of thyroid preparations.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Instruct patients to separate the administration time of thyroid preparations from calcium or iron by as much time as possible, preferably by at least four hours.(1) Administer thyroid preparations at least 2 hours before sucralfate.(5) Patients taking thyroid preparations and calcium- or iron-containing products or sucralfate should be monitored for changes in thyroid function. The dosage of the thyroid preparation may need to be increased. Separating the administration times of the thyroid preparation and the calcium- or iron-containing products or sucralfate may decrease the effects of the interaction.(1-5)
DISCUSSION: In a pharmacokinetic study 8 healthy, euthyroid adults were given levothyroxine alone and levothyroxine coadministered with calcium carbonate, calcium citrate, or calcium acetate in doses containing 500 mg elemental calcium. The coadministration of each of the three calcium preparations significantly reduced levothyroxine absorption by about 20%-25% compared with levothyroxine given alone.(3) In a study in 14 subjects, the simultaneous administration of thyroxine with ferrous sulfate for 12 weeks resulted in an increase in the mean level of thyroid stimulating hormone (TSH) from 1.6+/-0.4 mU/L to 5.4+/-2.8 mU/L. Mixing thyroxine with ferrous sulfate in vitro resulted in a poorly soluble complex.(4) In a study in 20 hypothyroid patients, the simultaneous administration of levothyroxine and calcium carbonate (1200 mg) daily for three months resulted in reductions in the mean free T4 and total T4 levels. These values increased in most patients following the discontinuation of calcium carbonate. A concurrent in-vitro study found that calcium carbonate adsorbed levothyroxine in solution at a pH of 2, gastric pH, but not at a pH of 7.4.(6) One author reported three cases of decreased levothyroxine efficacy following the addition of calcium carbonate to therapy.(7) In a study in 5 healthy subjects, levothyroxine (five 200 mcg tablets) was administered in 3 different dosing regimens: after an overnight fast, with the fifth and final dose of sucralfate (1 gram every 6 hours) and 8 hours after the second and final dose of sucralfate (2 grams every 12 hours). When administered alone, 80% of levothyroxine was absorbed within 6 hours of administration, compared to 23% when administered concurrently with sucralfate. There was no difference in levothyroxine absorption when administered alone or 8 hours after sucralfate.(8) There are several case reports documenting decreased effects of thyroid supplementation as the result of simultaneous administration of sucralfate.(9,10) One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.
Calcium; Iron; Sucralfate/Tiratricol
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The mechanism by which malabsorption of thyroid preparations such as tiratricol occurs from calcium-containing products is presumed to be a binding of the medication to the thyroid hormone, forming an insoluble or nonabsorbable complex.(1,2) Iron may form a ferric-thyroxine complex with thyroid agents such as tiratricol, preventing their absorption from the gastrointestinal tract.(1,2) Sucralfate binds to other agents in the gastrointestinal tract and alters absorption of other drugs, including thyroid agents such as tiratricol.(1-3)
CLINICAL EFFECTS: The simultaneous administration of thyroid preparations with calcium, iron, or sucralfate may result in decreased levels and clinical effects of thyroid preparations.(1,2)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Instruct patients to take iron and calcium supplements at the same time every day relative to tiratricol dosing.(6,7) Patients taking thyroid preparations and calcium- or iron-containing products or sucralfate should be monitored for changes in thyroid function. The dosage of the thyroid preparation may need to be increased. Separating the administration times of the thyroid preparation and the calcium- or iron-containing products or sucralfate may decrease the effects of the interaction.(1-3)
DISCUSSION: Iron and calcium may interfere with the absorption of tiratricol.(1,2)
Di-; Trivalent Cations/Chloroquine; Hydroxychloroquine
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Di- and trivalent cations such as aluminum, calcium, lanthanum, and magnesium may adsorb chloroquine and hydroxychloroquine; preventing their absorption.(1-5) The adsorption may also limit the effectiveness of the di- or trivalent cation.(1)
CLINICAL EFFECTS: Simultaneous administration of di- or trivalent cations may result in decreased levels and effectiveness of chloroquine and hydroxychloroquine(2-5) and decreased effectiveness of the di- or trivalent cation.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Instruct patients to separate the administration times of these medicines by 2 to 4 hours.(2,3)
DISCUSSION: Adsorption of chloroquine by magnesium trisilicate was found to decrease hydrochloric acid uptake and decrease the amount of magnesium released in an acidic environment.(1) In a study, calcium carbonate, kaolin, and magnesium trisilicate were found to decrease the absorption of chloroquine by 52.8%, 46.5%, and 31.3%, respectively.(3) Magnesium trisilicate and magnesium oxide have been shown to decrease the release of chloroquine from tablets and to adsorb chloroquine after its release.(4) In a study in 6 subjects, magnesium trisilicate and kaolin decreased the area-under-curve (AUC) of chloroquine by 18.2% and 28.6%, respectively.(5)
Divalent & Trivalent Cations/Tetracyclines
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Di- and trivalent cations may form chelation complexes with tetracyclines, preventing their absorption.(1,2)
CLINICAL EFFECTS: Simultaneous administration of di- or trivalent cations may result in decreased levels of and therapeutics effects from tetracyclines.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Administer tetracyclines at least two hours before or after the di- or trivalent cations. When used for the treatment of H. pylori infection, tetracyclines and bismuth should be given simultaneously. The US manufacturer of omadacycline states to fast for at least four hours, administer omadacycline, and then wait four hours before taking di- or trivalent cations.(21) The US manufacturer of ferric maltose recommends separation of ferric maltose by at least 4 hours.(22)
DISCUSSION: Concurrent administration of aluminum hydroxide or divalent cations (such as calcium, magnesium, or zinc) has been shown to significantly decrease the gastrointestinal absorption of tetracycline.(3-5) Concurrent administration of tetracycline and magnesium-aluminum hydroxide gel has been shown to decrease the tetracycline area-under-curve (AUC) by 90%.(6) Magnesium-aluminum silicate has been shown to decrease the AUC of tetracycline by 27%.(7) Demeclocycline(8,9) methacycline,(10) chlortetracycline,(11) and oxytetracycline(10,12) have been shown to interact with aluminum hydroxide and/or dairy products. Doxycycline has been reported to interact with aluminum hydroxide gel.(13) Aluminum magnesium hydroxide has been shown to decrease doxycycline absorption by 84%.(14) Minocycline absorption has been shown to be impaired by aluminum, calcium, and magnesium.(15) Bismuth subsalicylate has been shown to decrease absorption of doxycycline and tetracycline by 37%(16) and 34%,(17) respectively. Since sucralfate is an aluminum salt of a sulfated disaccharide, it may also prevent absorption of tetracyclines. This complex has been used to provide site-specific delivery of tetracycline to gastric ulcers in the treatment of Helicobacter pylori gastric ulcer disease and may be useful in some indications.(18) Quinapril tablets contain a high percentage of magnesium and have been shown to decrease the absorption of tetracycline by 28-37%.(19) Lanthanum is expected to interact with tetracyclines as well.(20)
Fat Soluble Vitamins/Colesevelam
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Colesevelam may decrease the absorption of fat-soluble vitamins A, D, E, and K.(1)
CLINICAL EFFECTS: Colesevelam may reduce absorption of fat soluble vitamins, leading to a deficiency state.
PREDISPOSING FACTORS: A pre-existing deficiency of fat soluble vitamins (A,D,E and K) or chronic malabsorption syndrome.
PATIENT MANAGEMENT: The inhibition of fat soluble vitamin absorption by colesevelam should be borne in mind during implementation of a vitamin supplementation strategy. Oral multivitamin supplements should be taken at least four hours before the dose of colesevelam.(1)
DISCUSSION: Colesevelam may decrease the absorption of fat-soluble vitamins A, D, E, and K.(1)
Fat Soluble Vitamins/Orlistat
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: The acetate ester forms of vitamin A and vitamin E must undergo hydrolysis for absorption from the gastrointestinal tract.(1) The enzyme responsible for this hydrolysis is inhibited by orlistat.(2)
CLINICAL EFFECTS: Orlistat may reduce absorption of fat soluble vitamins, leading to a deficiency state.
PREDISPOSING FACTORS: A pre-existing deficiency of fat soluble vitamins (A,D,E and K) or chronic malabsorption syndrome.
PATIENT MANAGEMENT: The inhibition of fat soluble vitamin absorption by orlistat should be borne in mind during implementation of a vitamin supplementation strategy. Patients should be strongly encouraged to take a multivitamin supplement which contains fat soluble vitamins, particularly Vitamin D as it appears most susceptible to this interaction.(4,5) Multivitamin supplements should be taken at least two hours before or after the dose of orlistat, or at bedtime.(4) Patients with chronic malabsorption syndromes should not receive orlistat.(4)
DISCUSSION: Adult patients taking orlistat without supplementation showed a greater reduction in vitamin A,D,E and beta-carotene levels compared to placebo during two or more consecutive visits in studies of 1-2 years duration; these patients had normal baseline values prior to orlistat therapy. Low vitamin values in orlistat patients were as follows: low Vitamin D 12%, low beta-carotene 6.1%, low Vitamin E 5.8%, low Vitamin A 2.2%.(4) A pharmacokinetic interaction study showed a 30% reduction in beta-carotene supplement absorption and a 60% decreased in vitamin E acetate absorption with concomitant orlistat.(4) In a study, orlistat produced the vitamin net concentration by approximately 43%.(1) In a study, no statistically significant decrease in vitamin A absorption was observed with concurrent orlistat.(2) In a study, mean vitamin D levels were significantly reduced compared with baseline after one month of orlistat therapy despite multivitamin supplementation.(5)
Folic Acid/Pafolacianine
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Folate, folic acid, and folate-containing supplements may reduce binding of pafolacianine to folate receptors expressed on ovarian cancer cells.
CLINICAL EFFECTS: Folate, folic acid, and folate-containing supplements could reduce the detection of malignant lesions with pafolacianine.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: Avoid administration of folate, folic acid, or folate-containing supplements within 48 hours before administration of pafolacianine.
DISCUSSION: Folate, folic acid, and folate-containing supplements may reduce binding of pafolacianine to folate receptors expressed on cancer cells, which could result in reduced detection of malignant lesions with pafolacianine.
Folic Acid; Pyrimethamine/Hydantoins
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Unknown, but probably involves altered metabolism of the hydantoin.
CLINICAL EFFECTS: May observe decreased effectiveness of hydantoin, resulting in loss of seizure control.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: If both drugs are administered, monitor both the hydantoin plasma levels as well as the seizure control of the patient. Adjust the dose of hydantoin accordingly.
DISCUSSION: The effects of an interaction are not expected to occur in the majority of patients. Discontinuation of folic acid has caused phenytoin levels to increase in patients who experienced a decrease in phenytoin levels when folic acid was started. Monitor these patients for hydantoin toxicity. Signs and symptoms of hydantoin toxicity include ataxia, nystagmus and involuntary movements.
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)
Oral Calcium Products/Estramustine
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Calcium may bind to estramustine in the gastro-intestinal tract, preventing its absorption.(1-4)
CLINICAL EFFECTS: Simultaneous administration of oral calcium products may result in decreased levels and clinical effectiveness of estramustine.(1-4)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The UK(1) and US(2) manufacturers of estramustine state that calcium containing products should not be taken simultaneously with estramustine. One Australian manufacturer of calcium carbonate recommends separating administration by at least 3 hours.(3)
DISCUSSION: In a randomized, cross-over study in 6 patients, simultaneous administration of estramustine (420 mg) with milk (200 ml containing 120 mg calcium) decreased the area-under-curve (AUC) and maximum concentration (Cmax) of estromustine (a metabolite of estramustine) by 59% and 68%, respectively. The AUC of estrone (another estramustine metabolite) was decreased by 63%.(4)
Oral Calcium Products/Strontium
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Calcium may prevent the absorption of strontium.(1,2)
CLINICAL EFFECTS: Simultaneous administration of strontium with oral calcium products may result in decreased levels and effectiveness of strontium.(1,2)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The administration of strontium and oral calcium products should be separated by at least 2 hours.(1,2)
DISCUSSION: Simultaneous administration of strontium with calcium or food decreased the bioavailability of strontium by 60-70% when compared to administration 3 hours after a meal.(1,2)
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/Cabotegravir
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Cabotegravir chelates polyvalent cations such as aluminum, calcium, iron, magnesium, selenium, and zinc.(1)
CLINICAL EFFECTS: Simultaneous administration of cabotegravir and polyvalent cations may decrease the absorption and clinical effects of cabotegravir.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The US manufacturer of cabotegravir states that it should be administered at least 4 hours before or 2 hours after any medications or products containing polyvalent cations such as antacids or mineral supplements.(1)
DISCUSSION: Clinical studies have not been conducted. Prescribing information states cabotegravir levels may be decreased when coadministered with antacids containing polyvalent cations (examples include aluminum or magnesium hydroxide, calcium carbonate) suggesting cabotegravir is susceptible to chelation.(1)
Polyvalent Cations/Eltrombopag
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Eltrombopag chelates polyvalent cations such as aluminum, calcium, iron, magnesium, selenium, and zinc.(1)
CLINICAL EFFECTS: Simultaneous administration of eltrombopag and polyvalent cations may decrease the absorption and clinical effects of eltrombopag.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The US manufacturer of eltrombopag states that it should be administered at least 2 hours before or 4 hours after any medications or products containing polyvalent cations such as antacids or mineral supplements.(1)
DISCUSSION: In a crossover study in 25 healthy subjects, administration of eltrombopag with an antacid (1524 mg aluminum hydroxide/1425 mg magnesium carbonate/sodium alginate) decreased eltrombopag levels by 70%.(1,2)
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/Roxadustat
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Roxadustat chelates polyvalent cations such as aluminum, calcium, iron, magnesium, selenium, and zinc.(1)
CLINICAL EFFECTS: Simultaneous administration of roxadustat and polyvalent cations may decrease the absorption and clinical effects of roxadustat.(1)
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: The manufacturer of roxadustat states that it should be administered at least 1 hour before or 1 hour after any medications or products containing polyvalent cations such as antacids or mineral supplements.(1)
DISCUSSION: Clinical studies with polyvalent cations have not been conducted. In a study in health subjects, concurrent use of roxadustat with sevelamer carbonate or calcium acetate decreased roxadustat area-under-curve (AUC) by 67% and 46% and concentration maximum (Cmax) by 66% and 52%, respectively.(1)
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)
Selected Oral Cations/Selected Oral Quinolones
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Aluminum, calcium, iron, lanthanum, magnesium, and zinc may form chelation compounds with the quinolones.(1-40)
CLINICAL EFFECTS: Simultaneous administration or administration of products containing aluminum, calcium, iron, lanthanum, magnesium, and/or zinc close to the administration time of an oral quinolone may result in decreased absorption and clinical effectiveness of the quinolone.
PREDISPOSING FACTORS: None determined.
PATIENT MANAGEMENT: If possible, avoid concurrent therapy with quinolones and cation-containing products. If it is necessary to administer these agents concurrently, follow the manufacturers' recommendations regarding timing of administration of the quinolone and cation-containing products. Manufacturer recommendations regarding the separation of administration times of quinolones and products containing aluminum, calcium, iron, lanthanum, magnesium, and/or zinc vary: ---Do not give ciprofloxacin for at least 2 hours before or 6 hours after oral cations.(1) ---Do not give delafloxacin for at least 2 hours before or 6 hours after oral cations.(2) ---Do not give enoxacin for at least 2 hours before or 8 hours after oral cations.(3) ---Do not give levofloxacin for at least 2 hours before or 2 hours after oral cations.(4) ---Do not give nalidixic acid for at least 2 hours before or 2 hours after oral cations.(5) ---Do not give norfloxacin for at least 2 hours before or 2 hours after oral cations.(6) ---Do not give ofloxacin for at least 2 hours before or 2 hours after oral cations.(7) ---Do not give sparfloxacin for at least 4 hours before oral cations.(8) ---Do not give sitafloxacin for at least 2 hours before or 2 hours after oral cations.(9) The US manufacturer of lanthanum recommends that quinolones be taken at least 1 hour before or 4 hours after lanthanum;(10) however, it would be prudent to follow the specific quinolone manufacturers' recommendations regarding concurrent administration of cations. The US manufacturer of ferric maltose recommends separation of ferric maltose by at least 4 hours. For quinolones not listed above, separate their administration from oral cations by as much time as feasible.
DISCUSSION: Aluminum, calcium, iron, magnesium, and zinc products have been shown to form chelation compounds with quinolone antibiotics, resulting in decreased absorption of the quinolone.(1-40) Treatment failures have been reported.(11-12) In a study in 12 healthy subjects, simultaneous administration of didanosine chewable tablets, which contain aluminum and magnesium, decreased ciprofloxacin area-under-curve (AUC) and maximum concentration (Cmax) by 92% and 98%, respectively.(14) The administration of ciprofloxacin 2 hours prior to Videx chewable/dispersible tablets decreased ciprofloxacin concentrations by 26%.(15,16) In a study in healthy subjects, pretreatment with an antacid containing aluminum-magnesium hydroxide at 5-10 minutes, 2 hours, and 4 hours before a single dose of ciprofloxacin decreased ciprofloxacin AUC by 84.9%, 76.8%, and 30%, respectively. There was no effect when the antacid was administered 6 hours before or 2 hours after.(17) In a study in 12 healthy subjects, aluminum hydroxide decreased ciprofloxacin AUC by 85%.(18) In a study in patients on continuous ambulatory peritoneal dialysis, peak levels of ciprofloxacin were decreased by 67% to 92% in patients receiving aluminum-containing antacids.(19) In a study in 15 healthy subjects, simultaneous administration of calcium acetate decreased the bioavailability of ciprofloxacin by 51%.(20) In a study in 6 healthy males, simultaneous administration of calcium carbonate decreased ciprofloxacin Cmax and AUC by 40% and 43%, respectively.(21) In a study in 12 healthy subjects, calcium carbonate decreased ciprofloxacin AUC by 40%.(18) In a study in 13 healthy males, calcium carbonate had no effect on ciprofloxacin bioavailability when administered 2 hours prior to the antibiotic.(22,23) In a study in healthy males, simultaneous administration of calcium polycarbophil decreased ciprofloxacin AUC by 50%.(24) In a study in 8 healthy males, simultaneous administration of ferrous fumarate (200 mg) decreased ciprofloxacin AUC by 70%.(25) In a study in healthy subjects, ferrous gluconate decreased ciprofloxacin bioavailability by 50%; however, no significant effects were seen with iron-ovotransferrin.(26) In a study in 8 healthy subjects, ferrous sulfate decreased the Cmax and AUC of simultaneously administered ciprofloxacin by 54% and 57%, respectively.(27) In a study in 8 healthy subjects, administration of ferrous sulfate decreased the Cmax and AUC of ciprofloxacin by 33% and 46%, respectively. Administration of ferrous gluconate decreased the Cmax and AUC of ciprofloxacin by 57% and 67%, respectively. Administration of a multivitamin product containing calcium, copper, iron, magnesium, manganese, and zinc decreased the Cmax and AUC of ciprofloxacin by 53% and 56%, respectively.(28) In a study in 12 healthy males, ferrous sulfate decreased ciprofloxacin AUC by 63%.(29) In a study in 12 healthy subjects, lanthanum carbonate decreased the area-under-curve (AUC) and maximum concentration (Cmax) of concurrently administered ciprofloxacin by 54% and 56%, respectively.(30) In a study in 12 healthy males, a multivitamin containing zinc decreased ciprofloxacin AUC by 22%.(29) In a study in 12 healthy subjects, an antacid containing aluminum-magnesium hydroxide had no effect on the pharmacokinetics of intravenous enoxacin.(31) In a study in 10 healthy subjects, administration of an aluminum-magnesium hydroxide antacid 0.5 hours or 2 hours before oral enoxacin (400 mg single dose) decreased the AUC of enoxacin by 73% and 43%, respectively. There were no significant effects on enoxacin AUC when the antacid was administered 8 hours before or 2 hours after enoxacin.(32) In a study in 9 healthy subjects, colloidal aluminum phosphate had no effect on the amount of enoxacin absorbed; however, ferrous sulfate (1050 mg) decreased the amount of enoxacin absorption by 10%.(33) In a study in 5 healthy subjects and 5 patients with cystic fibrosis, separation of levofloxacin (750 mg) and calcium carbonate (500 mg 3 times daily with meals) by 2 hours resulted in no interaction in healthy subjects; however, levofloxacin levels were not bioequivalent in patients with cystic fibrosis.(34) Concurrent magnesium-aluminum hydroxide or calcium have been shown to decrease the bioavailability of norfloxacin by 91.0% and 63.5%, respectively.(35) Concurrent zinc has been shown to decrease the bioavailability of norfloxacin.(36) In a study in 8 healthy subjects, ferrous sulfate decreased the Cmax and AUC of simultaneously administered norfloxacin by 75% and 73%, respectively.(27) Simultaneous aluminum phosphate was found to decrease the rate, but not the extent, of absorption of ofloxacin.(37) In a study in 8 healthy subjects, ferrous sulfate decreased the Cmax and AUC of simultaneously administered norfloxacin by 36% and 25%, respectively.(27) In an in vitro study, ferrous sulfate, aluminum hydroxide, and calcium carbonate decreased ofloxacin availability by 32.6%, 30.7%, and 26.2%, respectively. However, in vivo tests showed a significant effect with only aluminum hydroxide.(38) In a study in 9 healthy subjects, simultaneous administration colloidal aluminum phosphate had no effect on ofloxacin (200 mg) absorption; however, ferrous sulfate (1050 mg) decreased the ofloxacin fraction of dose absorbed by 10.85%.(33) In a study in 16 subjects, administration of either aluminum-magnesium hydroxide or calcium carbonate at least 2 hours before or after ofloxacin administration had no significant effects on ofloxacin levels.(39) The administration of an antacid containing aluminum hydroxide and magnesium hydroxide 2 hours before, 2 hours after, and 4 hours after sparfloxacin decreased sparfloxacin levels by 23%, 17%, and 5%, respectively.(40) One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.
Slt Cation-Donating Antacids/Polystyrene Sulfonate
SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.
MECHANISM OF ACTION: Polystyrene sulfonate may bind the cation from the antacid, resulting in increased intestinal absorption of non-neutralized bicarbonate, which may result in systemic alkalosis and decreased potassium binding by polystyrene sulfonate. Intestinal obstruction has occurred with aluminum hydroxide because of concretion.
CLINICAL EFFECTS: Simultaneous oral use may result in metabolic alkalosis and a decrease in the potassium lowering effect of polystyrene sulfonate. Intestinal obstruction has been reported with aluminum hydroxide.
PREDISPOSING FACTORS: Patients with renal failure may be at a higher risk of systemic alkalosis.
PATIENT MANAGEMENT: Consider the use of alternative agents to cation-donating antacids in patients receiving oral polystyrene sulfonate when possible. If concurrent use is required, separate the dosing by several hours.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well.
DISCUSSION: In a study in 11 patients with decreased renal function, the administration of magnesium hydroxide and sodium polystyrene sulfonate produced moderate to moderately severe metabolic alkalosis.(2) There are case reports documenting this affect as well.(3-7) Intestinal obstruction has been reported with aluminum hydroxide and sodium polystyrene sulfonate.(8) If the polystyrene sulfonate is administered rectally, a clinically significant interaction is not likely to occur.
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.
Contraindications
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- Hypercalcemia
- Hypercalcinuria
- Sarcoidosis
- Constipation
- Dehydration
- Gastrointestinal obstruction
- Hypercalcemia
- Insomnia
- Kidney stone
- Meconium ileus
- Pregnancy
- Sarcoidosis
- Anxiety disorder
- Carcinoma of breast
- Constipation
- Crohn's disease
- Disease of liver
- Endometrial carcinoma
- Fibrosing colonopathy
- Gastrointestinal tract surgery
- Gout
- Hyperparathyroidism
- Hypertension
- Hyperuricemia
- Kidney disease with reduction in glomerular filtration rate (GFr)
- Kidney stone
- Malignant neoplasm of the uterus
- Short bowel syndrome
Adverse reactions
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Rare or Very Rare
- Bronchospastic pulmonary disease
- Concentration difficulty
- Drug-induced hepatitis
Less Frequent
- Abdominal pain with cramps
Rare or Very Rare
- Abdominal distension
- Abdominal distension
- Abnormal vaginal bleeding
- Acute cognitive impairment
- Anorexia
- Constipation
- Constipation
- Cramps
- Depression
- Diarrhea
- Dizziness
- Dysgeusia
- Dyspepsia
- Dyspepsia
- Erythema
- Excitement
- Fatigue
- Flatulence
- Headache disorder
- Hypotension
- Irritability
- Irritability
- Loose stools
- Malaise
- Mastalgia
- Nausea
- Nausea
- Nausea
- Pruritus of skin
- Skin rash
- Skin rash
- Sleep disorder
- Weight gain
Precautions
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ICD codes
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Formulary status
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Last reviewed · Source: First Databank (FDB) drug data
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