NSAIDs Phenprocoumon

Studies surest that diclofenac does not alter the anticoagulant effect of acenocoumarol, phenprocoumon or warfarin, su esting dose adjustments are unlikely to be needed. Isolated cases of raised INRs have been described. Note that all NSAIDs increase the risk of gastrointestinal bleeding, and an increased risk is seen when they are combined with anticoagulants. 

There is limited evidence to suggest that diflunisal might increase the anticoagulant effects of acenocoumarol and possibly warfarin, but probably not phenprocoumon. All NSAIDs increase the risk of gastrointestinal bleeding, and should be used with care in patients taking oral anticoagulants. 

A single 1-g dose of metamizole sodium did not alter the steady-state anticoagulant effeets of either phenprocoumon (5 subjects) or ethyl biscoumacetate (6 subjects). Conversely, another report describes a short-lived but rapid increase (within 4 hours) in the effects of ethyl biscoumacetate caused by single 1-g dose metamizole sodium. The reasons are not understood. However, care is still needed with every NSAID , (p.427), because, to a greater or lesser extent, they irritate the stomach lining, which... 

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