Purpose: To investigate the pharmacokinetics of of a developed metoprolol and a reference standard (Mepressor^®).

Methods: Metoprolol tartrate-loaded Eudragit^® FS microparticles were formulated and compressed into tablets. The tablets were tested for their physicochemical properties according to United States Pharmacopoeia (USP) criteria. In vivo studies of the formulations were carried out in 28 young healthy fasting male volunteers based on a randomized open label 4×4 crossover study design with a washout period of 7 days.

Results: In vitro tests showed that the developed and reference standard of metoprolol tablets met compendia (USP) requirements. Zero order release of drug was observed from all the tablets. In vivo data demonstrated that there were significant (p < 0.05) differences in t_max, C_max, MRT, AUC_0−t, and AUC_0–∞ between the reference and test  (developed) formulations. However, the 90 % class interval for the mean ratios of the ln-transformed Cmax, AUC_0-t and AUC_0-α for the reference, T1, T2, and T3 lied in the bioequivalence range (80 to 125 %) indicating bioequivalence between the compared formulations.

Conclusion: It can be concluded from this single-dose study that the reference and test (developed) formulations met the predetermined criteria for bioequivalence in young healthy fasting male human subjects as the bioequivalence factor lie in the pre-determined limits for bioequivalence. Thus, the two formulations can be considered bioequivalent.