Abstract

Purpose: The present investigation was carried out to optimize the drug release pattern of a sustained release dosage form of metoprolol succinate. Method: The preparation of MS (metoprolol succinate) microspheres was carried out using poly (ε-caprolactone) at different polymer: drug ratios from 1:1 to 7:1 and 10:1 (F1 to F7 and F8) by the emulsion-solvent evaporation method. Physicochemical characterization of different ratios of formulations (F1 to F8) of microspheres was carried out such as the drug content, drug entrapped, particle size, bulk density and angle of repose. The in vitro drug release over 24 h was performed by the method specified in USP XXIV. Results: The bulk density and angle of repose data of the microspheres indicate their free flowing nature. The formulations with code F1 to F4 showed increased of drug entrapment (%) and F5 to F8 showed a steady amount of drug entrapment (%) with an increase in the amount of polymer. The formulation F4 (4:1 ratio) exhibited the most sustained effect over a period of 24 h with other formulations. It was found that the drug release kinetics followed the Korsmeyer–Peppas equation. The microspheres were spherical in shape with channeled surface as shown by SEM. The FT-IR spectrum showed no evidence of an interaction between drug and polymer. Conclusion: This approach optimizes the properties of the sustained release microspheres of metoprolol succinate, which can minimize both drug dose, and frequency of dosing. Formulation F4 proved to be the most stable.


Keywords:  Microspheres   Emulsion-solvent evaporation   Metoprolol succinate   Sustained release   Poly (ε-caprolactone)