The effect of isoniazid intake on ethionamide pharmacokinetics and target attainment in multidrug-resistant tuberculosis patients. Chirehwa, M. T, Court, R., de Kock, M., Wiesner, L., de Vries, N., Harding, J., Gumbo, T., Maartens, G., Warren, R., Denti, P., & McIlleron, H. Antimicrobial Agents and Chemotherapy, 65(10):e00278–21, jul, 2021.
The effect of isoniazid intake on ethionamide pharmacokinetics and target attainment in multidrug-resistant tuberculosis patients. [link]Paper  doi  abstract   bibtex   
Ethionamide is recommended as part of regimens to treat multidrug-resistant and rifampicin-resistant tuberculosis. The study was conducted to (i) describe the distribution of ethionamide minimum inhibitory concentrations (MICs), (ii) describe the pharmacokinetics of ethionamide, and (iii) determine the probability of attaining target AUC 0-24 /MIC values associated with suppression of resistant subpopulation and microbial kill. Participants received 15–20 mg/kg of ethionamide daily (in 500 or 750 mg doses), as part of a multidrug regimen. Pretreatment MICs of ethionamide for M. tuberculosis sputum isolates were determined using Sensititre MYCOTB MIC plates. Plasma concentrations of ethionamide (measured pre-dose and at 2, 4, 6, 8 and 10 hours post-dose) were available for 84 patients. A one-compartment disposition model including a liver compartment capturing hepatic extraction, best described ethionamide pharmacokinetics. Clearance and volume were allometrically scaled using fat-free mass. Isoniazid co-administration reduced ethionamide clearance by 31% resulting in a 44% increase in AUC 0-24 . The median (range) MIC (n=111) was 2.5 mg/L (\textless0.3 to \textgreater40 mg/L). Simulations showed increased daily doses of ethionamide (1 250 mg, 1 500 mg, and 1 750 mg for patients weighing ≤45 kg, 46-70 kg, and \textgreater70 kg, respectively) resulted in the probability of attaining a f AUC 0-24 /MIC ratio ≥ 42 in more than 90% of patients, only at the lowest MIC of 0.3 mg/L. The WHO recommended doses of ethionamide do not achieve target concentrations even for the lowest MIC measured in the cohort.
@article{Chirehwa2021,
abstract = {Ethionamide is recommended as part of regimens to treat multidrug-resistant and rifampicin-resistant tuberculosis. The study was conducted to (i) describe the distribution of ethionamide minimum inhibitory concentrations (MICs), (ii) describe the pharmacokinetics of ethionamide, and (iii) determine the probability of attaining target AUC 0-24 /MIC values associated with suppression of resistant subpopulation and microbial kill. Participants received 15–20 mg/kg of ethionamide daily (in 500 or 750 mg doses), as part of a multidrug regimen. Pretreatment MICs of ethionamide for M. tuberculosis sputum isolates were determined using Sensititre MYCOTB MIC plates. Plasma concentrations of ethionamide (measured pre-dose and at 2, 4, 6, 8 and 10 hours post-dose) were available for 84 patients. A one-compartment disposition model including a liver compartment capturing hepatic extraction, best described ethionamide pharmacokinetics. Clearance and volume were allometrically scaled using fat-free mass. Isoniazid co-administration reduced ethionamide clearance by 31{\%} resulting in a 44{\%} increase in AUC 0-24 . The median (range) MIC (n=111) was 2.5 mg/L ({\textless}0.3 to {\textgreater}40 mg/L). Simulations showed increased daily doses of ethionamide (1 250 mg, 1 500 mg, and 1 750 mg for patients weighing ≤45 kg, 46-70 kg, and {\textgreater}70 kg, respectively) resulted in the probability of attaining a f AUC 0-24 /MIC ratio ≥ 42 in more than 90{\%} of patients, only at the lowest MIC of 0.3 mg/L. The WHO recommended doses of ethionamide do not achieve target concentrations even for the lowest MIC measured in the cohort.},
author = {Chirehwa, Maxwell T and Court, Richard and de Kock, Mariana and Wiesner, Lubbe and de Vries, Nihal and Harding, Joseph and Gumbo, Tawanda and Maartens, Gary and Warren, Rob and Denti, Paolo and McIlleron, Helen},
doi = {10.1128/AAC.00278-21},
file = {:C$\backslash$:/Users/01462563/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Chirehwa et al. - 2021 - The effect of isoniazid intake on ethionamide pharmacokinetics and target attainment in multidrug-resistant tub.pdf:pdf},
journal = {Antimicrobial Agents and Chemotherapy},
keywords = {original},
mendeley-tags = {original},
month = {jul},
number = {10},
pages = {e00278--21},
pmid = {34310215},
title = {{The effect of isoniazid intake on ethionamide pharmacokinetics and target attainment in multidrug-resistant tuberculosis patients.}},
url = {https://journals.asm.org/doi/10.1128/AAC.00278-21},
volume = {65},
year = {2021}
}

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