Antidepressant interactions with warfarin.

The interactions between warfarin and antidepressants can have potentially serious consequences resulting from enhanced or reduced anticoagulant activity. Information about such interactions was obtained from a Medline and hand search of the published literature, and by directly contacting manufacturers. The different classes of antidepressants are discussed in turn. The possible mechanisms are considered with particular reference to the cytochrome p450 system. From currently available data on the newer antidepressants our conclusions are that citalopram, nefazodone and sertraline may be relatively less likely to interact with warfarin. Fluoxetine, fluvoxamine, paroxetine and moclobemide appear to have the highest potential of the antidepressants for interactions. There is insufficient data on venlafaxine to make a prediction. The clinical implications of these findings are discussed and specific recommendations for International Normalized Ratio monitoring are suggested.