GLUCAGON AND WARFARIN AND OTHER ORAL ANTICOAGULANTS

The anticoagulant effects of warfarin are rapidly and markedly increased by glucagon in large doses (62 to 362 mg over 3 to 8 days), and bleeding can occur. This interaction did not occur in patients given, in total, less than 30 mg of glucagon over 1 to 2 days.
It has been suggested that if glucagon 25 mg per day or more is given for two or more days, the dosage of warfarin should be reduced in anticipation of the interaction, and prothrombin times closely monitored. Information about other anticoagulants is lacking, but it would be prudent to assume that all coumarins will interact similarly.