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Drug Interactions between cyclophosphamide and amiodarone

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

amiodarone cycloPHOSphamide

Applies to: amiodarone and cyclophosphamide

MONITOR: One case report suggests that coadministration of amiodarone and cyclophosphamide may result in increased risk of pulmonary toxicity. The exact mechanism of interaction is unknown, although both agents can individually cause pulmonary toxicity such as pulmonary fibrosis and interstitial pneumonitis and may have additive effects on the lungs during coadministration. In the case report, a patient who had been on amiodarone therapy developed biopsy-proven pulmonary toxicity a little over two weeks after receiving a single, high dose of cyclophosphamide (4000 mg/m2). The time frame was much shorter than would have been predicted with cyclophosphamide alone, suggesting an accelerated pathogenic process. The patient had previously tolerated lower doses of cyclophosphamide while receiving treatment with amiodarone.

MANAGEMENT: Caution is advised during coadministration of amiodarone and cyclophosphamide, particularly at high dosages. Patients should be advised to notify their physician if they experience cough, dyspnea, or any new respiratory symptoms.

References

  1. Bhagat R, Sporn TA, Long GD, Folz RJ (2001) "Amiodarone and cyclophosphamide: potential for enhanced lung toxicity." Bone Marrow Transplant, 27, p. 1109-11

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Drug and food interactions

Major

amiodarone food

Applies to: amiodarone

GENERALLY AVOID: Grapefruit juice may significantly increase the plasma concentrations of orally administered amiodarone. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. In 11 nonsmoking, healthy volunteers, grapefruit juice (300 mL with drug administration, then 3 hours and 9 hours later) increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of amiodarone (17 mg/kg single dose) by 84% and 50%, respectively, compared to water. Formation of the pharmacologically active metabolite, N-desethylamiodarone (N-DEA), was completely inhibited. Clinically, this interaction can lead to altered efficacy of amiodarone, since antiarrhythmic properties of amiodarone and N-DEA appear to differ. In the study, mean increases in PR and QTc intervals of 17.9% and 11.3%, respectively, were observed 6 hours postdose with water, while increases of 10.2% and 3.3%, respectively, were observed after administration with grapefruit juice.

ADJUST DOSING INTERVAL: Food increases the rate and extent of absorption of amiodarone. The mechanism appears to involve the effect of food-induced physiologic changes on drug release from its formulation. In 30 healthy volunteers, administration of a single 600 mg dose of amiodarone following a high-fat meal resulted in a Cmax and AUC that were 3.8 and 2.4 times the respective values under fasting conditions. The time to reach peak plasma concentration (Tmax) was decreased by 37%, indicating an increased rate of absorption. Mean Cmax and AUC for the active metabolite, N-DEA, also increased by 32% and 55%, respectively, but there was no change in the Tmax.

MANAGEMENT: Patients treated with oral amiodarone should avoid consumption of grapefruits and grapefruit juice. In addition, oral amiodarone should be administered consistently with regard to meals.

References

  1. (2002) "Product Information. Cordarone (amiodarone)." Wyeth-Ayerst Laboratories
  2. Libersa CC, Brique SA, Motte KB, et al. (2000) "Dramatic inhibition of amiodarone metabolism induced by grapefruit juice." Br J Clin Pharmacol, 49, p. 373-8
  3. Meng X, Mojaverian P, Doedee M, Lin E, Weinryb I, Chiang ST, Kowey PR (2001) "Bioavailability of Amiodarone tablets administered with and without food in healthy subjects." Am J Cardiol, 87, p. 432-5

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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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