The pharmacokinetics of lamivudine in healthy Chinese subjects

Aims The purpose of this study was to investigate the pharmacokinetics of d aily oral doses of lamivudine administered to healthy Chinese subjects for 1 week. Methods Twenty-four subjects were enrolled, 12 males and 12 females, all be tween the ages of 18 and 40 years. After an overnight fast, all subjects re ceived a single oral dose of 100 mg lamivudine. Blood was obtained before l amivudine administration and at regular intervals to 24 h post dose. Subseq uent doses were given once daily for a total of 7 days. On the last day ano ther full pharmacokinetic profile was obtained to 24 h postdose. Timed urin e collections were performed for all subjects on day 1 only. Pharmacokineti c parameters were calculated by using standard non compartmental techniques . Results Lamivudine was well absorbed in all subjects (t(max) 1 h). On day 1 and day 7 the overall geometric mean C-max was 1304 and 1385 ng ml(-1), an d AUC(0,24h) was 4357 and 4353 ng ml(-1) h, respectively. On average 78% of the lamivudine dose was recovered in urine as parent compound. Pharmacokin etic parameters were very similar between male and female subjects, between day 1 and day 7 and in comparison with data obtained in many other pharmac okinetic studies. Conclusions This study demonstrated that the pharmacokinetics of lamivudine are essentially identical between Chinese and Caucasian subjects, and betw een males and females. It confirms 100 mg lamivudine is an appropriate dose for use in Chinese patients, providing adequate exposure for optimal antiv iral effect.