Psychotropic interactions with warfarin.

Abstract

OBJECTIVE: Improving knowledge about the cytochrome p450 system means that potential drug interactions can be predicted. Interactions involving warfarin may be thus avoidable. As many patients who have suffered from a stroke or other thromboembolic events may also develop psychiatric disorder, knowledge about possible interactions with psychotropics is essential for prescribers. METHOD: A Medline and hand search of published literature was complemented by contacting manufacturers. RESULTS: The antidepressants citalopram, nefazodone and sertraline have relatively low interaction potential with warfarin; fluoxetine and fluvoxamine relatively high. Carbamazepine appears to reduce warfarin's anticoagulant effect. Other antipsychotics, antidepressants and anxiolytics have only a theoretical risk of interaction. Lithium, gabapentin, sulpiride and amisulpride are predominantly renally excreted and so are not likely to interact with warfarin. CONCLUSION: Many psychotropics are involved in predictable interactions with warfarin. Drugs with a known low interaction potential should be chosen instead of those known or predicted to interact.