interactions
Last reviewed 01/2018
Amiodarone is metabolised by hepatic cytochrome P450 3A4(CYP 3A4) isoenzyme:
- concomitant administration of CYP 3A4 inhibitors should either be avoided or used only with caution
- CYP 3A4 inducers (e.g. carbamazepine, rifampicin) may lead to a reduction in amiodarone's plasma concentration and therefore reduce efficacy
- amiodarone itself inhibits CYP 3A4 and therefore will increase plasma concentrations of drugs such as ciclosporin, phenytoin and verapamil
Other important interactions with amiodarone include:
- potentiation of the effects of warfarin (inhibits metabolism via CYP 3A4)
- reduces excretion of digoxin (leads to increased plasma concentration)
- contra-indicated with other drugs that prolong the QT interval (e.g. disopyramide, quinidine, procainamide); only specialists should co-prescribe and monitor such drug therapy
Reference:
- Drug and Therapeutics Bulletin (2003), 41 (2), 9-12.