An Investigation into the Effect of Carbopols on the Release of Propranolol HCl from Tablet Matrices

In this study, attempts were made to evaluate the effect of various acrylic acid based Carbopols on the release profile of a beta-adrenoreceptor blocking drug, propranolol HCl, from matrix-type tablets invitro. For this purpose, tablets containing 160 mg of propranolol HCl along with various amounts of Carbopols 934 (C934), 971 (C971), 974 (C974) and Pemulen (Pem) were prepared using the wet granulation technique. Tablets prepared were placed in a USP apparatus I dissolution tester containing a pH 1.5 HCl solution for the first 2 h of this study and a pH 6.8 phosphate buffer for the next 10 h of the study. The amount of drug released was determined using the constructed calibration curves at 289 nm, using a uv-visible spectrophotometer. The results showed that tablets containing Pem are unsuitable for preparing tablets with desirable drug release profiles. In contrast, C971, C974 and C934 were all found to be suitable for this purpose at concentrations of 14, 16 and 12%, respectively. Tablets containing C971 were found to have the slowest profile of drug release, while C934 containing tablets had the greatest drug release profile among the Carbopols investigated. Hence, Carbopols 971, 974 and 934 are found to be suitable, when used alone, for the preparation of propranolol HCl hydrophilic matrix-type tablets.