Pharmacokinetics and Bioequivalence of 2 Azithromycin Tablet Formulations: A Randomized, Open-Label, 2-Stage Crossover Study in Healthy Volunteers

The current study aimed to assess the bioequivalence of a new branded azithromycin with the reference formulation. An open-label, randomized, 2-stage, crossover study design was implemented involving 77 healthy volunteers under fasting conditions. Each volunteer received a single dose of 250-mg azithromycin tablets test and reference formulations separated by a 21-day washout period. Twenty-two samples were collected at pre-dose and until 72 hours post-dose. Azithromycin concentrations were analyzed using a high-performance liquid chromatography-mass spectrometry validated method following a solid-phase plasma extraction. Noncompartmental analysis was carried out to estimate the pharmacokinetic parameters, which were compared between the test and reference products using a multivariate analysis of variance. The difference between C-max and AUC(0-72) of the test and reference formulation was not significant. The 94.1% confidence intervals of ln-transformed C-max and AUC(0-72) of azithromycin were within the bioequivalence acceptance limits of 80%-125%, therefore it can be concluded that the tested formulation is bioequivalent to the reference formulation.