Pharmacokinetics of Levornidazole Tablet in Healthy Chinese Subjects and Proposed Dosing Regimen Based on Pharmacokinetic/Pharmacodynamic Analysis

INTRODUCTION: Levornidazole is a novel nitroimidazole antimicrobial agent active against anaerobes. We aimed to investigate the pharmacokinetic (PK) profile of levornidazole after single and multiple oral doses of levornidazole tablets in healthy Chinese subjects and propose the dosing regimen based on pharmacokinetic/pharmacodynamic (PK/PD) analysis. METHODS: A single-center, randomized, double-blind, placebo-controlled study was conducted with a single ascending dose (250, 500, 1000, and 1500 mg) and multiple doses of 500 mg levornidazole q12h for 7 days. Food effect on PK and absolute bioavailability were investigated at the 500 mg dose level. Blood and urine samples were collected to determine the PK parameters of levornidazole. The probability of target attainment (PTA) and cumulative fraction of response (CFR) were calculated by Monte Carlo simulation to predict the clinical efficacy of levornidazole tablets. RESULTS: Plasma concentration reached peak about 0.5 h after single dose (250–1500 mg) of levornidazole tablets. The maximal concentration (C(max)) and exposure (AUC(0–∞)) of levornidazole increased linearly with dose. High-fat diet did not affect the absorption extent of levornidazole tablets. The absolute oral bioavailability of levornidazole tablets was 98.3% ± 7.6%, associated with large apparent volume of distribution (48.68 ± 4.92 l) and long half-life (11.93 ± 1.28 h). The urinary excretion of levornidazole was 7.99%. Levornidazole, administered at either 500 mg q12h or 750 mg q24h, achieved a CFR > 95.4% and PTA > 99% for B. fragilis (minimum inhibitory concentration ≤ 1.0 mg/l) infections. CONCLUSION: Levornidazole tablets are absorbed rapidly and completely and distributed extensively with a long half-life and low urinary excretion after a single dose or multiple doses in healthy Chinese subjects. Levornidazole tablets can be taken with or without food. Levornidazole tablets 500 mg q12h and 750 mg q24h are expected to achieve the desired efficacy in B. fragilis infections. CLINICAL TRAIL REGISTRATION: Trial registration number CTR20160786 at http://www.chinadrugtrials.org.cn/.