Ascorbic acid prevents contrast-mediated nephropathy in patients with renal dysfunction undergoing coronary angiography or intervention

Background - Contrast agents can cause a reduction in renal function that may be due to the generation of reactive oxygen species. Conflicting evidence suggests that administration of the antioxidant acetylcysteine prevents this renal impairment. The action of other antioxidant agents has not been investigated. Methods and Results - We conducted a randomized, double-blind, placebo-controlled trial of ascorbic acid in 231 patients with a serum creatinine concentration greater than or equal to 1.2 mg/dL who underwent coronary angiography and/or intervention. Ascorbic acid, 3 g at least 2 hours before the procedure and 2 g in the night and the morning after the procedure, or placebo was administered orally. Contrast-mediated nephropathy was defined by an absolute increase of serum creatinine greater than or equal to 0.5 mg/dL or a relative increase of greater than or equal to 25% measured 2 to 5 days after the procedure. Contrast-mediated nephropathy occurred in 11 of the 118 patients (9%) in the ascorbic acid group and in 23 of the 113 patients (20%) in the placebo group (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.17 to 0.85; P = 0.02). The mean serum creatinine concentration increased significantly in the placebo group ( from 1.36 +/- 0.50 to 1.50 +/- 0.54 mg/ dL, P < 0.001) and nonsignificantly in the ascorbic acid group ( from 1.46 +/- 0.52 to 1.52 +/- 0.64 mg/ dL, P = 0.07). The mean increase in serum creatinine concentration was greater in the placebo group than in the ascorbic acid group ( difference of 0.09 mg/ dL; 95% CI, 0.00 to 0.17; P = 0.049). Conclusions - Prophylactic oral administration of ascorbic acid may protect against contrast-mediated nephropathy in high-risk patients undergoing a coronary procedure.