Pharmacokinetics-pharmacodynamics of first-line antitubercular drugs: a comparative study in tuberculosis patients with and without concomitant diabetes mellitus

To observe the variability in the plasma concentrations and pharmacokinetic-pharmacodynamic (PK-PD) profiles of first-line antitubercular drugs in pulmonary tuberculosis (TB) patients with and without diabetes mellitus (DM).

Newly diagnosed pulmonary TB patients aged 18–60 years with or without DM were included in the study. Group I (n = 20) included patients with TB, whereas group II (n = 20) included patients with both TB and DM. After 2 weeks of therapy, plasma concentrations and other PK-PD parameters were determined. Improvements in clinical features, X-ray findings, sputum conversion, and adverse drug reactions (ADRs) were assessed after 2 months of therapy.

Isoniazid displayed non-significantly higher plasma concentrations in diabetic patients, along with a significantly (P < 0.05) longer elimination half-life (t_1/2). Rifampicin plasma concentrations at 4, 8, and 12 h were significantly (P < 0.05) lower, and it displayed significantly (P < 0.05) lower area under the curve (AUC_0-12 and AUC_0-∞), shorter t_1/2, higher clearance (Cl), and a lower AUC_0-∞/MIC ratio in diabetic patients. Pyrazinamide and ethambutol showed non-significantly higher plasma concentrations, AUC_0-12, AUC_0-∞, and t_1/2 in diabetic patients. The improvements in clinical features, X-ray findings, sputum conversion, and ADRs were comparable in both groups.

The presence of DM in TB patients affects the PK-PD parameters of isoniazid, rifampicin, pyrazinamide, and ethambutol variably in the Indian population. Studies with a larger number of patients are required to further elucidate the role of DM on the PK-PD profile of first-line antitubercular drugs and treatment outcomes in TB patients with concomitant DM.

CTRI/2021/08/035578 dated 11/08/2021.