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 activitity, it appears unlikely that an increased tendency to haemorrhage arises in patients after intake of Umckaloabo®.