Interaction between heparin and acetylsalicylic acid on gastric mucosal and skin bleeding in humans.

The haemorrhagic effect of unfractionated heparin and of the low molecular weight heparin, enoxaparin, on gastric mucosal bleeding induced by acetylsalicylic acid (ASA) and on skin bleeding induced by the Simplate technique was investigated in healthy human volunteers. Endoscopic estimation of gastric bleeding by visual analogue scores was more sensitive than biochemical quantitation of blood in the gastric washing by a modified HaemoQuant method. Contrary to what was expected, the ASA-induced gastric mucosal bleeding was not increased by heparin pretreatment, whereas heparin in combination with ASA, but not ASA alone, significantly increased the skin bleeding time. In the interaction with ASA, enoxaparin and unfractionated heparin appeared to act similarly.