Treatment of rats with the Pelargonium sidoides extract EPs 7630 has no effect on blood coagulation parameters or on the pharmacokinetics of warfarin.

Umckaloabo is a herbal drug for the treatment of respiratory tract infections. It contains an aqueous ethanolic extract from roots of Pelargonium sidoides DC (EPs) 7630) as the active ingredient. Polymeric polyphenols and coumarins have been identified as the principal ingredients of EPs 7630. In view of the coumarin content, it has been suggested that the administration of Umckaloabo could possibly be associated with an increased risk of bleeding. This study, therefore, investigated whether a change in blood coagulation parameters or an interaction with coumarin-type anticoagulants occurred after administration of EPs 7630 to rats. No effect on thromboplastin time (TPT), partial TPT (PTPT) or thrombin time (TT) was observed after oral administration of EPs 7630 (10, 75, 500 mg/kg) for 2 weeks, while treatment with warfarin (0.05 mg/kg) for the same period resulted in significant changes in TPT and PTPT. If EPs 7630 (500 mg/kg) and warfarin (0.05 mg/kg) were given concomitantly, the anticoagulant action of warfarin was not influenced. Similarly, the pharmacokinetics of warfarin were unchanged after pre-treatment with EPs 7630 for 2 weeks. Coumarin-type anticoagulants inhibit the synthesis of vitamin K-dependent coagulation factors via an identical mechanism in rat and man, and have a similar pattern of metabolism in both species. Moreover, as the coumarins so far identified in EPs 7630 do not posses the structural characteristics needed for anticoagulant activity, it appears unlikely that an increased tendency to haemorrhage arises in patients after intake of Umckaloabo.