Purpose: The aim of the study was to compare plasma concentrations of rifampicin (RMP), isoniazid (INH) and pyrazinamide (PZA) between tuberculosis (TB) patients with and without diabetes mellitus (DM).
Methods: Two-hour post-dosing concentrations of RMP, INH and PZA were determined in adult TB patients that were studied with (n = 452) and without DM (n = 1460), treated with a thrice-weekly regimen in India. Drug concentrations were estimated by HPLC.
Results: The median (IQR) INH [6.6 (3.9-10.0) and 7.8 (4.6-11.3)] and PZA [31.0 (22.3-38.0) and 34.1 (24.6-42.7)] microgram per milliliter concentrations were significantly lower in diabetic than non-diabetic TB patients (p < 0.001 for both drugs). Blood glucose was negatively correlated with plasma INH (r = -0.09, p < 0.001) and PZA (r = -0.092, p < 0.001). Multiple linear regression analysis showed RMP, INH and PZA concentrations were influenced by age and drug doses, INH and PZA by DM, RMP by alcohol use and PZA by gender and category of ATT. DM reduced INH and PZA concentrations by 0.8 and 3.0 μg/ml, respectively.
Conclusions: TB patients with DM had lower INH and PZA concentrations. Negative correlation between blood glucose and drug concentrations suggests delayed absorption/faster elimination of INH and PZA in the presence of elevated glucose.
Keywords: Anti-tuberculosis drug concentrations; Diabetes mellitus; Revised National Tuberculosis Control Programme; Tuberculosis.