Pharmacokinetics of N-acetylcysteine following repeated intravenous infusion in haemodialysed patients

Objective: N-acetylcysteine (NAC) is a mucolytic agent with anti-oxidant properties. It might have potential positive effects in renal patients and, therefore, its pharmacokinetics and safety in haemodialysis was investigated. Methods: Twelve dialysis patients received 2 g NAC (10 ml NAC 20% solution i.v.) mixed with 500 ml saline during the first 3 h of the session for six dialysis sessions. A bolus of heparin was injected intravenously as LWH-heparin. In six patients, one session was repeated with NAC mixed with heparin and infused through the heparin pump. Results: Baseline NAC was on average 454 ng ml(-1); its concentration increased to 9,253 ng ml(-1) at the second infusion and attained a steady state between 14,000 ng ml(-1) and 17,000 ng ml(-1) at the fourth dose. We observed a C-max of 53,458 ng ml(-1) with a t(max) of 3.0 h. Plasma clearance was 1.25 l h(-1) and dialytic clearance 5.52 l h(-1). No side effects were observed. Conclusion: In the case of repeated doses, the NAC pre-dose concentration after repeated infusion of 2 g of the drug during the first 3 h of a dialysis session reached the steady state at the fourth infusion, without further accumulation. The dialytic clearance is effective, the total body clearance being reduced to 1.25 l h(-1). In dialysis patients, 2 g NAC given intravenously over 3 h is a safe dosage, with no short-term side effects.