The effectiveness of oral N-acetylcysteine administered three hours before angiography in the prevention of contrast nephropathy in patients with mildly elevated creatinine levels

OBJECTIVES
We evaluated the effectiveness of oral N-acetylcysteine (NAC) in the prevention of contrast nephropathy, when administered three hours before angiography in conjunction with parenteral hydration therapy.

STUDY DESIGN
This double-blind study included 81 patients (58 men, 23 women; mean age 62±10 years) with mildly elevated (1.4 mg/dl to 2 mg/dl) blood creatinine levels. Before elective coronary angiography, the patients were randomized to receive, in addition to hydration therapy (1000 ml 0.9% NaCl), 600 mg NAC before three hours and 600 mg NAC after six hours of the procedure (n=40) or placebo (n=41). Contrast nephropathy was defined as a 25% or 0.5 mg/dl increase in blood creatinine levels measured on Day 2 and Day 7 following the procedure.

RESULTS
There were no significant differences between the two groups with respect to age, sex, risk factors, baseline creatinine levels, and the amount of contrast medium used. Creatinine levels significantly increased in both groups 48 hours after the procedure (p<0.05), but they returned to near-baseline levels on Day 7, at which time 20 patients (50%) in the NAC group, and 17 patients (42%) in the placebo group had the same or lower creatinine levels compared to the baseline. The incidence of nephropathy did not differ significantly (p>0.05); two patients (5%) in the NAC group, and four patients (10%) in the placebo group developed contrast nephropathy, all of which improved in the first week without the need for dialysis.

CONCLUSION
Hydration therapy is the most efficient way to prevent contrast nephropathy. Administration of NAC on the same day seems to provide no additional benefits.