Pharmacokinetics and Safety of Single and Multiple Doses of Oral N-Acetylcysteine in Healthy Chinese and Caucasian Volunteers: An Open-Label, Phase I Clinical Study

This single- and multiple-dose, single-centre, open-label, phase I clinical study was conducted in healthy adult volunteers. All participants received oral NAC 600-mg uncoated tablets, which were administered first as a single dose and, following a 48-h wash-out period, twice daily for 3 days. Blood and urine were collected after single- and multiple-dose NAC administration. Adverse event (AE) data were collected throughout the study.

Fifteen Chinese and 15 Caucasian (mostly Italian) individuals (males 66.7%, mean age 36.8 years) participated in the study. Pharmacokinetic characteristics of NAC were similar in the two cohorts. Following both single- and multiple-dose administration, plasma concentration of NAC increased rapidly, reaching a peak at approximately 1.0 h. Maximum plasma concentration and extent of exposure were higher after multiple doses than after a single dose. The accumulation ratio was relatively consistent in both Chinese (mean ± standard deviation 1.5 ± 0.4) and Caucasian (1.4 ± 0.2) participants. The half-life was 15.4 h in Chinese and 18.7 h in Caucasian participants, and the fraction of NAC excreted in urine in the 36 h following administration was 3.7% in Chinese and 3.8% in Caucasian participants. Two Caucasian participants had a total of 3 AEs (headache, presyncope and dysmenorrhoea). No AEs occurred in Chinese participants.

The pharmacokinetic characteristics of NAC are similar in healthy Chinese and Caucasian individuals after single and repeated administration. NAC has a favourable tolerability profile.