Aricept Evess Drug Interactions

Donepezil HCl and/or any of its metabolites does not inhibit the metabolism of theophylline, warfarin, cimetidine or digoxin in humans. The metabolism of donepezil HCl is not affected by concurrent administration of digoxin or cimetidine. In vitro studies have shown that the cytochrome P-450 isoenzymes 3A4 and to a minor extent 2D6 are involved in the metabolism of donepezil. Drug interaction studies performed in vitro show that ketoconazole and quinidine, inhibitors of CYP3A4 and 2D6, respectively, inhibit donepezil metabolism. Therefore, these and other CYP3A4 inhibitors eg, itraconazole and erythromycin, and CYP2D6 inhibitors eg, fluoxetine could inhibit the metabolism of donepezil. In a study in healthy volunteers, ketoconazole increased mean donepezil concentrations by about 30%. Enzyme inducers eg, rifampicin, phenytoin, carbamazepine and alcohol may reduce the levels of donepezil. Since the magnitude of an inhibiting or inducing effect is unknown, such drug combinations should be used with care. Donepezil HCl has the potential to interfere with medications having anticholinergic activity. There is also the potential for synergistic activity with concomitant treatment involving medications eg, succinylcholine, other neuromuscular-blocking agents or cholinergic agonists or β-blocking agents which have effects on cardiac conduction.
Incompatibilities: Not applicable.