Pharmacokinetic Properties and Tolerability of Cycloserine Following Oral Administration in Healthy Chinese Volunteers: A Randomized, Open-Label, Single- and Multiple-Dose 3-Way Crossover Study

Purpose: A new generic formulation of cycloserine has been developed in China but the pharmacokinetic properties of cycloserine in the Chinese population have not been reported. The aim of our study was to evaluate the pharmacokinetic properties and tolerability of single and multiple oral administrations of cycloserine capsules in healthy Chinese volunteers. Methods: This open-label, single- and multiple-dose 3-way crossover study was conducted in healthy Chinese volunteers. Subjects were randomized to receive a single dose of cycloserine (250, 500, or 1000 mg) in separate trial periods, with a 1-week washout between periods. Those allocated to the 250-mg dose continued into the multiple-dose phase, in which they received 250 mg BID for 5 consecutive days. During the single-dose phase, blood samples were collected at regular intervals from 0 to 72 hours after drug administration and the concentrations of cycloserine were determined using LC-MS/MS. During the multiple-dose phase, blood samples were obtained before drug administration on Days 4, 5, and 6 to determine the Cinin at steady state. On Day 6, blood samples were also collected from 0 to 72 hours after drug administration. Pharmacokinetic parameters were estimated using noncompartmental methods. Tolerability was determined using clinical evaluation and monitoring of adverse events. Findings: The study enrolled 12 healthy Chinese volunteers (6 men: mean [SD] age = 23.0 [2.6] years, weight =- 60.2 [6.2] kg, height = 170.0 [3.0] cm, and body mass index = 20.7 [1.7]; 6 women: mean [SD] age = 25.3 [1.4] years, weight = 51.5 [3.3] kg, height = 160.0 [4.0] cm, and body mass index = 20.1 [0.9]). After administration of a single dose, cycloserine was rapidly absorbed, reaching peak plasma concentrations approximately 0.84 hours after oral administration, and t(1/2) in plasma was about 13.0 hours. The geometric mean (SD) C-max value increased in proportion to cycloserine dose, from 19.42 (5.89) to 84.76 (21.74) mg/L, and the geometric mean (SD) AUC(0-72h) value increased from 264.16 (133.37) to 1153.87 (522.16) mg. h/L in the range of a 250- to 1000-mg dose. After administration of multiple doses of cycloserine 250 mg BID, the mean (SD) t(1/2) was 13.56 (4.38) hours, the apparent total clearance of the drug from plasma after oral administration was 1.02 (0.42) L/h, and the apparent volume of distribution was 18.22 (5.25) L, which were comparable with those after single dosing. The accumulation index was 2.19 (0.51), and the fluctuation was 1.05 (0.35). Results of the t tests of Cmax and AUC found no significant differences between the male and female groups. No serious adverse events were reported, and there were no discontinuations due to adverse events. Implications: The pharmacokinetic properties of cycloserine were linear at doses from 250 mg to 1000 mg. After multiple doses, the pharmacokinetic properties of cycloserine were consistent with those after single doses. At the doses studied, cycloserine appears to be well tolerated in these healthy volunteers. Chinese Clinical Trials registration: ChiCTR-TTRCC-13003982. (C) 2015 Published by Elsevier HS Journals, Inc.