RESUMEN
AIM: We report the prevalence and effect of genetic variability on pharmacokinetic parameters of isoniazid and rifampicin. MATERIALS & METHODS: Genotypes for SLCO1B1, NAT2, PXR, ABCB1 and UGT1A genes were determined using a TaqMan® Genotyping OpenArray™. Nonlinear mixed-effects models were used to describe drug pharmacokinetics. RESULTS: Among 172 patients, 18, 43 and 34% were classified as rapid, intermediate and slow NAT2 acetylators, respectively. Of the 58 patients contributing drug concentrations, rapid and intermediate acetylators had 2.3- and 1.6-times faster isoniazid clearance than slow acetylators. No association was observed between rifampicin pharmacokinetics and SLCO1B1, ABCB1, UGT1A or PXR genotypes. CONCLUSION: Clinical relevance of the effects of genetic variation on isoniazid concentrations and low first-line tuberculosis drug exposures observed require further investigation.