By Ashley Starkweather, B.S. and Asher Kimchi M.D.

Athens, Greece – Ascorbic acid was found to decrease the incidence of contrast-mediated nephropathy (CMN) in patients with renal insufficiency undergoing percutaneous coronary angiography. Published in the November 2, 2004 issue of Circulation, investigators Konstantinos Sparias, MD, et al, from the Onassis Cardiac Surgery Centre in Athens, Greece, enrolled 238 patients in a randomized, double-blind, placebo-controlled trial that tested the efficacy of ascorbic acid in preventing CMN in coronary angiography patients with a baseline serum creatinine concentration of >1.2 ml/dL.  

Ascorbic acid has a well established history as a safe dietary supplement in humans, and based on previous trials of the antioxidant acetylcysteine, the possibility of using ascorbic acid as a prophylatic treatment for CMN was explored. 

Patients undergoing nonemergent coronary angiography or intervention at the Onassis Cardiac Surgery Centre in Athens, Greece, who had a baseline serum creatinine concentration of >1.2 ml/dL within three months prior to the procedure were included in the study.  

Patients were randomly assigned to receive either 3 g of ascorbic acid via chewable tablet or placebo at least 2 hours before the procedure, followed by 2 g ascorbic acid or placebo the night and morning after the procedure. 

Baseline serum creatinine concentration was measured from a sample drawn at the time of randomization, and follow-up levels were drawn at 2 and 5 days post-procedure. CMN was defined as an absolute rise in serum creatinine concentration of at least 0.5mg/dL or a relative rise of at least 25% from baseline. 

231 patients completed the study out of the 238 patients enrolled. In the control group, the mean serum creatinine concentration increased from 1.36 to 1.50 mg/dL, while in the ascorbic acid group it only increased from 1.46 to 1.52 mg/dL. The increase in the placebo group was significantly larger than in the ascorbic acid group. 

CMN, by the investigator’s definition, occurred in 9% of the ascorbic acid group, compared to 20% of the control group.  

Furthermore, the mean baseline serum creatinine concentration and age tended to be higher and the baseline creatinine clearance lower in the ascorbic acid group. However, the ascorbic acid group still showed a lower rate of CMN despite these random inbalances in factors that have been shown in previous studies to increase the risk of CMN. 

The results of this study show that ascorbic acid, a safe, well-tolerated, inexpensive, and readily available oral antioxidant, appears to prevent the occurrence of CMN after invasive coronary imaging procedures in patients with pre-existing renal dysfunction. Furthermore, these findings are consistent with the hypothesis that CMN is caused in whole or in part by oxidative stress.  

Co-authors were Elias Alexopoulos, MD; Stamatis Kyrzopoulos, MD; Panayiotis Iacovis, MD; Darren C. Greenwood, MSc; Athanassios Manginas, MD; Vassilis Voudris, MD; Gregory Pablides, MD; Christopher E. Buller, MD; Dimitrios Kremastinos, MD; Dennis V. Cokkinos, MD