Final Analysis Analysis will be by intention-to-treat. For the efficacy parameter, a comparison will be made between COM and the average of SOB and NAC (the primary analysis). Pair-wise comparisons may also be made between COM and each of SOB and NAC. Tests for significance will be conducted using the chi-squared test for the primary endpoint. Relative risks and their 95% confidence intervals will be presented for the primary analysis and, although not powered to demonstrate equivalence, between SOB and NAC. Further analysis will be conducted using logistic regression to adjust for potential risk factors. For binary saftey outcomes (need for hemodialysis within 30 days and 30-day mortality) and adverse events, the chi-squared test or Fisher's exact test will be used. T-tests or Wilcoxon-signed rank tests will be used for continuous saftey outcomes (maximum change in serum creatinine level within 30 days, length of hospital stay, maximum change in GFR within 30 days and peak creatinine level within 48 hours and 30 days). A two-tailed significance level of p<0.05 will be used for all endpoints at the final analysis.