The objectives of this study were to compare dissolution profiles of a verapamil (VRP) formulation manufactured in-house and Isoptin SR using USP Apparatus 2 and 3 and to elucidate drug release kinetics of these dosage forms. Eudragit NE 30D (ethyl acrylate-methyl methacrylate copolymer in a 2:1 ratio) aqueous dispersion was used as a granulating binder for the manufacture of VRP mini-matrix sustained-release tablets.The wet granulation process was performed to prepare free-flowing granules that were blended with Carbopol.The tablets were manufactured using a single-punch press by compression of the granules with magnesium stearate as a lubricant. Drug release was determined in phosphate buffer solution using USP Apparatus 2 and 3. Dissolution data were fitted to zero- and first-order models; in addition, the kinetic data were determined by evaluation of Higuchi release kinetics.The mechanism of drug release was established using the Korsmeyer-Peppas model. In general, all tablets showed high mechanical resistance with less than 1 friability. There was no significant difference between the dissolution profiles of the formulation manufactured in-house and the commercially available product.The release mechanism of the formulated and marketed products was controlled by anomalous non-Fickian diffusion. VRP release was prolonged for 12 h indicating the usefulness of the formulation as a twice-daily dosage form.The mechanism of drug release for the dosage forms was unaffected by the choice of apparatus.
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