Anticoagulants interaction with medications

Unwanted side effects and undesirable interactions can occur when herbals are taken with prescription medication. For example, Coumadin, which is an anticoagulant, interacts with ginkgo, an herb that inhibits platelets, resulting in increased bleeding and stroke. 

In two of the five spontaneous bleeding episodes described in Heading 4, medications that can affect platelet function or prothrombin time (PT) (i.e., aspirin and warfarin) were involved. Because GB is known to be an inhibitor of PAF (41), in theory GB could interact with antiplatelet drugs (e.g., aspirin, nonsteroidal anti-inflammatory drugs, clopidogrel, ticlopidine, dipyridamole) or anticoagulants (e.g., warfarin, heparin). EGb 761 was shown to potentiate the antiplatelet effect of ticlopidine in rats (42). However, in two studies in humans, the coadministration of GB with warfarin had no effect on either international normalized ratio or warfarin metabolism (43,44). 

Warfarin was also implicated in several interactions with antiviral medications. A recent case series suggests an interaction between warfarin and oseltamivir (Tamiflu). Among 15 patients on anticoagulation tiierapy who took oseltamivir, 7 had an increase in INR levels and the remaining 8 maintained stable INR levels. Bleeding events such as blood-tinged sputum and bloody ascites occurred in three patients in the increased INR group [13 ]. 

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