Clinical Pharmacokinetics of Levornidazole in Elderly Subjects and Dosing Regimen Evaluation Using Pharmacokinetic/Pharmacodynamic Analysis

Population pharmacokinetics of levornidazole in healthy subjects and patients, and sequential dosing regimen proposal using pharmacokinetic/pharmacodynamic analysis

Although sequential treatment with levornidazole has been used for anaerobic infection in clinical practice, there is no evidence-based dosing regimen. This study aimed to evaluate the pharmacokinetics (PK) of levornidazole in healthy subjects and patients, and to propose an evidence-based sequential dosing regimen by pharmacokinetic/pharmacodynamic (PK/PD) analysis. A population PK model was built using the data of 116 Chinese subjects, including 88 healthy young subjects, 12 healthy elderly subjects, and 16 patients with intra-abdominal anaerobic infection. PK/PD analysis was performed combining the minimum inhibitory concentration (MIC) values of levornidazole against 375 anaerobic strains. Four sequential dosing regimens (500 mg q12h, 1000 mg loading dose followed by 500 mg q12h, 750 mg q24h, and 1000 mg q24h) were evaluated in terms of cumulative fraction of response (CFR) and probability of target attainment (PTA) by Monte Carlo simulation. The concentration data of levornidazole and its active metabolites were described adequately by two- and one-compartment models, respectively. Body weight was identified as a significant covariate of levornidazole clearance. Simulations showed that satisfactory PTA (>90%) was achieved for the four dosing regimens when MIC ≤1 mg/L. Considering the simulation results, patients' safety and compliance, levornidazole 750 mg intravenous infusion q24h for 2 days followed by 750 mg oral dose q24h for 5 days was optimal for Bacteroides spp. with an identified MIC ≤1 mg/L.

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/ .