Controlled-Release Theophylline Tablet Formulations Containing Acrylic Resins

The purpose of this work was to study the film coating potential of grewia gum, extracted from the stem bark of Grewia mollis, using praziquantel as a model drug. Core tablets of praziquantel were prepared by wet granulation method and the physicochemical properties such as weight, hardness, friability and disintegration time were evaluated. Aqueous coating suspensions of grewia gum extract (2.5%w/w) with or without plasticizers were prepared and used to coat the tablets in an improvised coating pan. The coated tablets were evaluated for weight uniformity, diameter, thickness, hardness, friability, and disintegration time and moisture uptake at controlled humidity. The coating remained intact, durable and resistant to chipping when challenged to catastrophic fall or rubbed on a white paper. Hardness of coated tablets improved by 40% and the disintegration time was extended five- fold compared to the core tablets. There were changes in the amount of moisture absorbed, which was dependent on the formulation and the environmental condition. The formulation of grewia gum without plasticizer and that containing polyethylene glycol 4000 were of better quality compared to those with glycerin and propylene glycol.