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Steady‐state population pharmacokinetics of terizidone and its metabolite cycloserine in patients with drug‐resistant tuberculosis
Author(s) -
Mulubwa Mwila,
Mugabo Pierre
Publication year - 2019
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/bcp.13975
Subject(s) - pharmacokinetics , cycloserine , volume of distribution , population , metabolite , pharmacology , medicine , tuberculosis , pathology , environmental health
Aims Despite terizidone being part of the second‐line recommended drugs for treatment of drug‐resistant tuberculosis (DR‐TB), information on its pharmacokinetics is scarce. The aim of this study was to describe the steady‐state population pharmacokinetics (PPK) of terizidone and its primary metabolite cycloserine in patients with DR‐TB and determine the effect of patient characteristics. Methods This clinical study involved 39 adult DR‐TB patients admitted to Brewelskloof Hospital in Cape Town, South Africa for intensive treatment phase. Blood samples were collected at predose and 0.5, 1, 2, 3, 3.5, 4, 8, 16 and 24 hours after drug administration. The estimation of PPK parameters was performed using nonlinear mixed‐effects modelling software Monolix 2018R1. Free‐fat mass was used to perform allometric scaling on disposition parameters. Results A 1‐compartment model best described the pharmacokinetics of terizidone and cycloserine. A modified transit compartment model described the absorption of terizidone. The parameters of terizidone model were mean transit time (1.7 h), absorption rate constant (2.97 h −1 ), apparent volume of distribution ( Vp/F : 13.4 L) and apparent total clearance (0.51 L h −1 ). In the joint model, apparent fraction of terizidone converted to cycloserine was 0.29 while apparent clearance of terizidone via other routes and apparent cycloserine clearance was 0.1 L h −1 and 2.94 L h −1 , respectively. Serum albumin had significant effect on Vp/F . Conclusions The developed PPK model described well the concentration–time profile for terizidone and cycloserine in DR‐TB patients. High albumin concentration was associated with low Vp/F .