Formulation of metoprolol succinate solid dispersion by solvent evaporation method

The solid dispersion method was originally used to improve the dissolution properties and bioavailability of poorly water-soluble drugs by dispersing them in water-soluble carriers. In addition, dissolution retardation through the solid dispersion technique using water-insoluble and water-swellable polymers for the development of controlled-release dosage forms has become a field of interest. In recent years, significant attention has been paid to the use of solid dispersions for the development of sustained-release drugs. The objective of this study was to produce sustained-release systems of metoprolol succinate using solid dispersion techniques and evaluate their physicochemical characteristics. In the solvent method, dichloromethane (DCM), containing the drug and different ratios of HPMC K4M, HPMC K15M, and HPMC K100M, and ethyl cellulose in ratios of 0.5:1, 1:1, and 0.5:0.5:1, Drug release profiles were determined by the USP II rotating paddle method in phosphate buffer solution (pH 6.8). DSC, IR, and microscopic observations were performed to evaluate the physical characteristics of solid dispersions. The results showed that the drug release pattern of formulations including both HPMC K100 and ethyl cellulose was such that only ethyl cellulose functioned well, controlling the early burst and improving drug release within the first one–six hours. Solid dispersion batches containing different proportions of drug and ethyl cellulose were prepared for optimization, and in vitro drug release was investigated. Drug release was 90% in 12 h for formulations EF1 and EF2, which included polymer-drug ratios of 1.5:0.5 and 2.0:0.5, respectively. Likewise, at 24 h, formulations EF3 and EF4 demonstrated 100% drug release.