Tramadol Phenprocoumon

In a retrospective cohort study of patients taking acenocoumarol or phenprocoumon, tramadol was found to be assoeiated with a threefold increased risk of bleeding. The study was speeifieally looking at potentially interacting drugs taken by at least 50 patients and with at least 5 eases of bleeding. ... 

In one study tramadol did not change the mean HSR in response to phenprocoumon, although two patients had increases. Isolated cases of an increase in anticoagulant effects of warfarin and phenprocoumon have been reported. One retrospective cohort study also found an increased risk of bleeding when acenocoumarol or phenprocoumon was given with tramadol. 

In a double-blind, placebo-controlled, crossover study the mean INRs of 19 patients anticoagulated with phenprocoumon were unchanged when they were given tramadol 50 mg three times daily for a week,. - Although the mean difference was not changed, one patient had an INR rise from 4 to 7.3, and another from a just under 5 to 6, while taking tramadol, but not while taking placebo. 

Boeijinga JK, van Meegen E, van den Ende R, Schook CE, Cohen AF. Is there intemcticxi between tramadol and phenprocoumon Lancet 99T) 350,1552. 

Ivkidsen H, Rasmussen JM, Brosen K. Interaction between tramadol and phenprocoumon. Lun-ce/(1997) 350,637. 

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