Gastrointestinal bleeding coumarin anticoagulants

On the basis of the above studies, no coumarin dose adjustment would be expected to be needed with nabumetone. However, care is still needed with every NSAID , (p.427), because, to a greater or lesser extent, they irritate the stomach lining, which can result in gastrointestinal bleeding, which will be more severe in anticoagulated patients. 

An equal number of randomised studies have found a modest increase in the anticoagulant effect (e.g. an increase in HSR of 1) of coumarins as have reported no effect. One retrospective cohort study reported that concurrent use tends to increase the incidence of upper gastrointestinal bleeding, but other cohort studies found no evidence of a change in anticoagulant effect. There are isolated case reports of an increase in anticoagulant effects in patients taking warfarin or acenocoumarol and paracetamol... 

The principal adverse reaction to warfarin is hemorrhage. Prolonged therapy with the coumarin-type anticoagulants is relatively free of untoward effects. Bleeding may be observable (e.g., skin, mucous membranes) or occult (e.g., gastrointestinal, renal, cerebral, hepatic, uterine, or pulmonary). Rarer untoward effects include diarrhea, small intestine necrosis, urticaria, alopecia, skin necrosis, purple toes, and dermatitis. 

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