Anti-tuberculosis drug concentrations and treatment outcomes among HIV-infected patients with tuberculosis

Introduction: A poor response to tuberculosis (TB) treatment in patients with human immunodeficiency virus (HIV) infection can be related to inadequate adherence or low anti-tuberculosis drug concentrations in serum. Therapeutic drug monitoring (TDM) may be a useful tool to optimize drug therapy in these patients. This study aimed to determine serum concentrations of anti-TB drugs and treatment outcomes in HIV/TB patients. Material and methods: Twenty-two HIV/TB infected patients were entered into the study. Venous blood was obtained 2 h after a daily dose of isoniazid (INH), rifampin (RIF), and pyrazinamide (PZA). Serum levels of anti-TB drugs were analyzed using high pressure liquid chromatography (HPLC) and compared with published normal ranges. Treatment outcomes were assessed according to World Health Organization (WHO) definitions. Results: All the patients (median age: 35 years [range 27-57 years], median CD4+: 16 cells/mm(3) [range 5-444 cells/mm(3)]) had low or very low serum concentrations of INH and RIF. Serum concentration of PZA was in the reference (normal) range in 5 (22.73%) patients. Of 22 patients, 4 were considered cured, 10 died on TB treatment or during follow-up, 5 relapsed after treatment, and 3 were lost to follow-up. Conclussions: Low serum concentrations of anti-TB drugs and poor treatment outcomes are common among our patients. Further studies in a wider patient sample are required to explore the association between anti-TB drug concentrations and treatment outcomes.