Phenprocoumon requirement, whole blood coagulation time, bleeding time and plasma gamma-GT in patients receiving mianserin.

A possible interaction between the tetracyclic antidepressant mianserin and a coumarin derivative has been investigated. Sixty-three subjects, 61 of whom required anticoagulant therapy for a variety of medical conditions, were treated for 5 consecutive weeks with phenprocoumon, in a dose adjusted to reduce the prothrombin time to 15%-25%. After an initial control period of one week, subjects were randomly treated under double-blind conditions with mianserin 3 X 10 mg daily or 3 X 20 mg daily, or with a matching placebo. The dose of mianserin was gradually increased to reach the maximum by the 6th day. Three subjects dropped out and 60 completed the trial. The dose of phenprocoumon and the prothrombin, bleeding, and coagulation times were not significantly affected by administration of mianserin. It can be concluded that there is no clinically important interaction between phenprocoumon and doses of mianserin effective in depression. Sedation was more frequent in patients taking mianserin than in those given placebo.