Warfarin and Antidepressants: Happiness without Hemorrhaging.

Warfarin, a commonly prescribed anticoagulant, has a very narrow therapeutic index. Because a multitude of drugs may potentially alter warfarin levels, primarily through the cytochrome P-450 isoenzyme system, in this edition of The Interface, we explore drug interactions between warfarin and the antidepressants. According to the available data, sertraline and citalopram appear to be the safest antidepressants to use in patients on warfarin, whereas fluvoxamine and fluoxetine pose the highest potential risks. The remaining antidepressants appear to lie somewhere in between, with most having little empirical data to guide the practitioner other than the potential interactions of these drugs and warfarin in the cytochrome P-450 isoenzyme system.