Pentoxifylline does not interfere with stable coumarin anticoagulant therapy: a clinical study.

A study was undertaken to investigate the possible interaction between pentoxifylline and coumarin. Ten patients on a previously stable anticoagulant treatment were investigated twice prior to, then 13 and 27 days after initiation of treatment with 1600 mg pentoxifylline daily. Coumarin therapy was continued in unaltered dosage. Parameters recorded were: bleeding time, platelet count, platelet adhesivity, spontaneous and collagen-induced platelet aggregation, activated partial thromboplastin time, prothrombin time, prothrombin-proconvertin activity, plasminogen activator and fibrin(ogen) degradation products. Platelet aggregation studies revealed a slightly higher sensitivity to collagen in 2 patients compared to pre-treatment values and in 1 patient the tendency to spontaneous aggregation was slightly increased after treatment. No other single test result changed significantly from premedication baseline values.