Standard vs double dose of N-acetylcysteine to prevent contrast agent associated nephrotoxicity.

AIMS: Prophylactic administration of N-acetylcysteine (NAC) (600mg orally twice daily), along with hydration, prevents contrast agent-associated nephrotoxicity (CAN) induced by a low dose of non-ionic, low-osmolality contrast dye. We tested whether a double dose of NAC is more effective to prevent CAN. METHODS AND RESULTS: Two-hundred-twenty-four consecutive patients with chronic renal insufficiency (creatinine level > or =1.5mg/dl and/or creatinine clearance <60ml/min), referred to our institution for coronary and/or peripheral procedures, were randomly assigned to receive 0.45% saline intravenously and NAC at the standard dose (600mg orally twice daily; SD Group; n=110) or at a double dose (1200mg orally twice daily; DD Group; n=114) before and after a non-ionic, low-osmolality contrast dye administration. Increase of at least 0.5mg/dl of the creatinine concentration 48h after the procedure occurred in 12/109 patients (11%) in the SD Group and 4/114 patients (3.5%) in the DD Group (P=0.038; OR=0.29; 95% CI=0.09-0.94). In the subgroup with low (<140ml, or contrast ratio <=1) contrast dose, no significant difference in renal function deterioration occurred between the 2 groups. In the subgroup with high (> or =140ml, or contrast ratio >1) contrast dose, the event was significantly more frequent in the SD Group. Conclusions Double dose of NAC seems to be more effective than the standard dose in preventing CAN, especially with high volumes of non-ionic, low-osmolality contrast agent.