The effect of co-processed dry binder with microcrystalline cellulose on release of verapamil hydrochloride from hydrophilic matrix tablets

The aim of this study was to evaluate the use of co-processed dry binder MicroceLac®100 (lactose and microcrystalline cellulose in ratio 3:1) and Comprecel® 102 (pure microcrystalline cellulose) in formulations for the extended release of verapamil hydrochloride. Hydrophilic matrix tablets containing verapamil hydrochloride, hypromellose and dry binder were prepared by the direct compression method. Hypromelloses MethocelTM K4M Premium CR or MethocelTM K100M Premium CR were used as controlled release agents. Using scanning electron microscopy regular distribution of the active substance in the prepared tablets was confirmed. Release of verapamil hydrochloride from the prepared formulations was studied by the dissolution test method. The dissolution profiles were fitted to the first-order kinetic model, Higuchi diffusion model, Korsmeyer-Peppas and Weibull model and kinetic parameters as the first order release rate constant (k1), release exponent (n) from Korsmeyer-Peppas model, Higuchi constant (KH) and parameters of Weibull model (b, λ) were determined. Based on results of non-linear regression analysis, the higher release rate constants were found for formulations containing co-processed dry binder MicroceLac®100 in comparison with formulations containing pure microcrystalline cellulose (Comprecel® 102). In addition, tablets swelling, erosion and disintegration during the dissolution test were monitored photographically.