Pharmacokinetic Evaluation of Sulfamethoxazole at 800 Milligrams Once Daily in the Treatment of Tuberculosis

N Alsaad, J A Dijkstra, O W Akkerman, W C M de Lange, D van Soolingen, J G W Kosterink, T S van der Werf, J W C Alffenaar

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For treatment of multidrug-resistant tuberculosis (MDR-TB), there is a scarcity of antituberculosis drugs. Co-trimoxazole is one of the available drug candidates, and it is already frequently coprescribed for TB-HIV-coinfected patients. However, only limited data are available on the pharmacokinetic (PK) and pharmacodynamic (PD) parameters of co-trimoxazole in TB patients. The objective of this study was to evaluate the PK parameters and in vitro PD data on the effective part of co-trimoxazole: sulfamethoxazole. In a prospective PK study in patients infected with drug-susceptible Mycobacterium tuberculosis (drug-susceptible TB patients) (age, >18), sulfamethoxazole-trimethoprim (SXT) was administered orally at a dose of 960 mg once daily. One-compartment population pharmacokinetic modeling was performed using MW\Pharm 3.81 (Mediware, Groningen, The Netherlands). The area under the concentration-time curve for the free, unbound fraction of a drug (ƒAUC)/MIC ratio and the period in which the free concentration exceeded the MIC (fT > MIC) were calculated. Twelve patients received 960 mg co-trimoxazole in addition to first-line drugs. The pharmacokinetic parameters of the population model were as follows (geometric mean ± standard deviation [SD]): metabolic clearance (CLm), 1.57 ± 3.71 liters/h; volume of distribution (V), 0.30 ± 0.05 liters · kg lean body mass(-1); drug clearance/creatinine clearance ratio (fr), 0.02 ± 0.13; gamma distribution rate constant (ktr_po), 2.18 ± 1.14; gamma distribution shape factor (n_po), 2.15 ± 0.39. The free fraction of sulfamethoxazole was 0.3, but ranged between 0.2 and 0.4. The median value of the MICs was 9.5 mg/liter (interquartile range [IQR], 4.75 to 9.5), and that of theƒAUC/MIC ratio was 14.3 (IQR, 13.0 to 17.5). The percentage of ƒT > MIC ranged between 43 and 100% of the dosing interval. The PK and PD data from this study are useful to explore a future dosing regimen of co-trimoxazole for MDR-TB treatment. (This study has been registered at under registration no. NCT01832987.).

Original languageEnglish
Pages (from-to)3942-7
Number of pages6
JournalAntimicrobial Agents and Chemotherapy
Issue number7
Publication statusPublished - Jul 2016

Cite this

Alsaad, N., Dijkstra, J. A., Akkerman, O. W., de Lange, W. C. M., van Soolingen, D., Kosterink, J. G. W., ... Alffenaar, J. W. C. (2016). Pharmacokinetic Evaluation of Sulfamethoxazole at 800 Milligrams Once Daily in the Treatment of Tuberculosis. Antimicrobial Agents and Chemotherapy, 60(7), 3942-7.