Psychotropic interactions with warfarin.
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.


METHODS
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.


CONCLUSIONS
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.
Sayal
K S
KS
The Maudsley Hospital, London, UK.
Duncan-McConnell
D A
DA
McConnell
H W
HW
Taylor
D M
DM
D000925:Anticoagulants / Q000494:pharmacology* / Q000627:therapeutic use; D000928:Antidepressive Agents / Q000009:adverse effects / Q000494:pharmacology*; D003863:Depression / Q000188:drug therapy* / Q000209:etiology*; D004347:Drug Interactions; D006801:Humans; D007527:Isoenzymes / Q000187:drug effects; D020521:Stroke / Q000188:drug therapy / Q000523:psychology; D014859:Warfarin / Q000378:metabolism* / Q000627:therapeutic use
D000925:Anticoagulants; D000928:Antidepressive Agents; D007527:Isoenzymes; D014859:Warfarin