Sodium valproate, platelet dysfunction, and bleeding.

The antiepileptic drug sodium valproate (VPA) can provoke a thrombocytopenia or platelet dysfunction, with or without hemorrhages. These unwanted side effects are probably infrequent or, at least, have little clinical importance except in patients undergoing surgery. Thromboelastography appears to be a reliable screening test. As hematological abnormalities are often dose related, VPA dosages greater than 40 mg/kg/day are not advised.