Influence of combined administration of herbal complexes and warfarin on international normalized ratio in stroke and anoxic brain damage patients: A retrospective study

Aim of the studyWarfarin is commonly used for preventing thromboembolic diseases. Care is taken when administering warfarin, since combined therapy with other substances can affect the prothrombin time international normalized ratio (INR). Whether warfarin interacts with herbal medicines remains controversial. This study aimed to examine the effect of herbal complexes on INR in patients being treated with warfarin.MethodologyWe examined medical records of patients treated with a combination therapy of warfarin and herbal complexes from January 1, 2009 to December 31, 2010. We recorded changes in INR and tested the significance of the difference in INR using a paired T-test.ResultsTwenty-eight patients were identified. INR did not change significantly in this group of patients (p = 0.615). In 1 case, a dramatic change in INR was observed. However, this did not appear to occur in relation to combined warfarin and herbal complex therapy.ConclusionsThere is no strong evidence that herbal complexes have an influence on INR when taken in combination with warfarin. However, we propose that further evaluation of larger samples is required to reach a definite conclusion.