[The influence of diazepam (valium) on the effect of phenprocoumon (marcumar) (author's transl)]

In 10 patients who were treated with phenprocoumon (Marcumar) for thrombembolic diseases, we examined the influence of the combined therapy with diacepam (Valium) on the effect of the anticoagulant. After stopping the therapy with diacepam we saw a significant increase of the prothrombinetime (Quick) beyond the therapeutic level of 25%. By increasing the dosis of phenprocoumon the therapeutic level was achieved again not until after 8 days. The dosis needed for maintaining this level was on the average 32% higher than during the time of the therapy in which diacepam was used. Because of the increased thrombembolic risk, when going beyond the therapeutic level of the prothrombinetime, this interaction is of clinical importance.