Effect of allopurinol on the survival of hyperemic island skin flaps.

Allopurinol was investigated in 3 x 6 cm congested island skin flaps in rats. Eight hours of venous occlusion produced total flap necrosis. Pretreatment with systemic allopurinol, an inhibitor of xanthine oxidase, enhanced the survival rate of hyperemic skin flaps. Xanthine oxidase activities were demonstrated in skin, and these enzyme activities were noted to increase in skin flaps during ischemia and reperfusion. Much of this increase in enzyme activity was prevented by allopurinol treatment. The xanthine oxidase system appears to be one of the sources of the superoxide radical, which may be involved in ischemic and reperfusion injury in skin.