Basic Information
ID DDInter1589 and DDInter76
Interaction Coadministration with inducers of CYP450 3A4, such as rifamycins and St. John's wort, may decrease the serum concentrations of amiodarone and its metabolite desethylamiodarone (DEA) and result in therapeutic failure. The proposed mechanism is induction of CYP450 3A4 hepatic metabolism of amiodarone.
Management Monitoring serum amiodarone and DEA levels and patient's clinical status is recommended if CYP450 3A4 inducers are added to or deleted from a stable drug regimen that includes amiodarone. Alternative therapy or dosage adjustments may also be considered. Patients should be advised to notify their doctor if they experience worsening of their symptoms (e.g., palpitations or irregular heartbeat).
References [1] "Product Information. Cordarone Intravenous (amiodarone)." Wyeth-Ayerst Laboratories, Philadelphia, PA. [2] Zarembski DG, Fischer SA, Santucci PA, Porter MT, Costanzo MR, Trohman RG "Impact of rifampin on serum amiodarone concentrations in a patient with congenital heart disease." Pharmacotherapy 19 (1999): 249-51 [3] "Product Information. Cordarone (amiodarone)." Wyeth-Ayerst Laboratories, Philadelphia, PA. [4] Libersa CC, Brique SA, Motte KB, et al. "Dramatic inhibition of amiodarone metabolism induced by grapefruit juice." Br J Clin Pharmacol 49 (2000): 373-8 [5] Meng X, Mojaverian P, Doedee M, Lin E, Weinryb I, Chiang ST, Kowey PR "Bioavailability of Amiodarone tablets administered with and without food in healthy subjects." Am J Cardiol 87 (2001): 432-5 [6] "Product Information. Cordarone (amiodarone)." Wyeth-Ayerst Laboratories, Philadelphia, PA. [7] Patel S, Robinson R, Burk M "Hypertensive crisis associated with St. John's Wort." Am J Med 112 (2002): 507-8
Alternative for Rifabutin J04A
Streptomycin Trimethoprim Cycloserine Pyrazinamide Rifamycin Pyridoxine
Aminosalicylic acid Pretomanid

A02B
Bismuth subcitrate potassium Vonoprazan Tetracycline
More
Alternative for Amiodarone C01B
Flecainide Procainamide Propafenone Mexiletine Moricizine Tocainide
Ibutilide Bretylium
Potential Metabolism Interactions
Substrate-Substrate Interaction：If more than one drug is metabolized by the same CYP, it is possible that its metabolism is inhibited because of the competition between the drugs. That means, it can be useful to lower the dosage of the drugs in the drug-cocktail because they remain longer in the organism than in monotherapy.
Inhibitor-Inhibitor Interaction：Combining two or more inhibitors of one CYP, should be compensated by lowering the dosage of these drugs because the metabolism is reduced and the drugs remain longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.
Inhibitor-Substrate Interaction：Combining drugs that have inhibitory effect and are substrates of one particular CYP, should be compensated by lowering the dosage. They rest longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.