Bleeding, warfarin-induced

Absolute contraindications to warfarin include active bleeding, hemorrhagic tendencies, pregnancy, and a history of warfarin-induced skin necrosis. It should be used with great caution in patients with a history of GI bleeding, recent neurosurgery, alcoholic liver disease, severe renal... 

Drugs like salicylates, dipyridamole, phenylbutazone decrease the ability of platelets to aggregate, and thus impairing the haemostasis if warfarin induced bleeding occurs. 

Evans G, Luddington R, Baglin T. Beriplex P/N reverses severe warfarin-induced overanticoagulation immediately and completely in patients presenting with major bleeding. Br J Haematol 2001 115(4) 998-1001. 

One patient taking warfarin developed haematuria with a therapeutic prothrombin time three months after starting phenformin. Another patient developed metformin-induced lactic acidosis after warfarin-induced bleeding caused renal obstruction. However, these interactions are isolated and seem unlikely to be of general importance. 

Patients at increased risk of NSAID-induced gastrointestinal adverse effects (e.g., dyspepsia, peptic ulcer formation, and bleeding) include the elderly, those with peptic ulcer disease, coagulopathy, and patients receiving high doses of concurrent corticosteroids. Nephrotoxicity is more common in the elderly, patients with creatinine clearance values less than 50 mL/minute, and those with volume depletion or on diuretic therapy. NSAIDs should be used with caution in patients with reduced cardiac output due to sodium retention and in patients receiving antihypertensives, warfarin, and lithium. 

Pridiard PJ, Kitchingman GK, Walt RP Daneshmend TK, Hawkey CJ Human gastric mucosal bleeding induced by low dose aspirin, but not warfarin. Brit. Med. J. 298 493, 1989... 

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