Pharmacokinetics of two pharmaceutical presentations of benznidazole in adult Trypanosoma cruzi infected population.

Background: Benznidazole (BNZ) is the primary treatment for Chagas disease. While pharmacokinetic studies of BNZ began in the 1970s, its metabolism and excretion are not fully understood. Alternatives like Benznidazol Lafepe® and Abarax® have replaced the original Radanil®.

Objectives: To compare the pharmacokinetic profiles of both currently available formulations of BNZ in adults with chronic Trypanosoma cruzi infection.

Methods: The study involved 13 subjects each one receiving 100 mg of both presentations one week apart. Blood samples were collected over 48 hours post-administration to analyse BNZ concentration and calculate pharmacokinetic parameters.

Findings: The analysis showed that both presentations had similar maximum plasma concentration and time to reach maximum plasma concentration values. Area under curve (AUC) values were slightly lower in Abarax® than Benznidazol Lafepe®. High intra-individual variability was observed, attributed to erratic absorption patterns with multiple peaks in concentration-time curves. The half-life values for both formulations were 9.1 and 8.0 h, respectively, with a significant intra-individual variability over 30%.

Main Conclusions: The mean difference in the AUC was lower than 10%, but exceeded the 90% confidence interval for the higher bioequivalence limit. Despite the high variability that confirms erratic absorption, the pharmacokinetic parameters of both formulations were within expected ranges.