Inhibition of phenprocoumon anticoagulation by carbamazepine

Eur Neuropsychopharmacol. 2000 May;10(3):219-21. doi: 10.1016/s0924-977x(00)00056-0.


Carbamazepine inhibits warfarin and dicoumarol anticoagulation through induction of cytochrome P450-enzymes. Inhibition of phenprocoumon anticoagulation by carbamazepine has been supposed in some reviews, however, without hard empirical evidence. We report a patient who was anticoagulated with phenprocoumon in whom carbamazepine produced a dramatic increase in prothrombin time ratio (Quick). After discontinuation of carbamazepine, Quick-values returned to therapeutic levels. Valproate did not affect phenprocoumol's anticoagulant properties. The potentially hazardous carbamazepine-phenprocoumon interaction should be emphasized in reference drug manuals.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anticoagulants / therapeutic use
  • Antimanic Agents / therapeutic use*
  • Carbamazepine / therapeutic use*
  • Drug Interactions
  • Dysthymic Disorder / drug therapy*
  • Female
  • Humans
  • Middle Aged
  • Phenprocoumon / therapeutic use
  • Prothrombin Time
  • Venous Thrombosis / drug therapy


  • Anticoagulants
  • Antimanic Agents
  • Carbamazepine
  • Phenprocoumon