Effects of allopurinol on oxygen stress status during open heart surgery.

We tested the hypothesis that allopurinol reduces the levels of markers of oxygen free radical production during open heart surgery. Eighteen patients undergoing coronary artery bypass grafting were randomly assigned to the allopurinol group (10 patients), which received 600 mg of allopurinol before operation, or to the control group (eight patients). Blood samples were taken from the coronary sinus and the radial artery before the cardiopulmonary bypass 2, 10 and 20 min after the aortic cross-clamp was released, as well as 5 min after the cardiopulmonary bypass. The samples were used to calculate transcardiac gradients of: ratio of erythrocyte oxidized to reduced glutathione, and of plasma malondialdehyde, creatinine kinase-MB isoenzyme and lactic acid. After the clamp release, there was a significant increase in all the calculated transcardiac gradients. The gradient of a ratio of erythrocyte oxidized to reduced glutathione showed a significantly smaller increase in the allopurinol group (P = 0.0176) with no significant difference between groups for plasma malondialdehyde, creatinine kinase-MB isoenzyme and lactic acid gradients. The data suggest that allopurinol diminishes free radical production, but with no effect on subsequent lipid peroxidation and cellular injury in low-risk patients with coronary artery disease undergoing open heart surgery.