Development and characterization of isradipine compression coated controlled release mini-tablets

The intent of present study is to develop the Isradipine controlled release tablets through compression coating of mini-tablets with the help of hydrophilic and hydrophobic polymers. Isradipine mini-tablets were prepared by direct compression method and compression coated using various concentrations of HPMC K15M, Ethyl cellulose and combination of Ethyl cellulose and HPMC K15M. The prepared tablets were characterized for weight variation, hardness, thickness, friability, drug content and swelling studies. Formulations were evaluated for the release of Isradipine over a period of 12 h using type-II USP XXIV standard dissolution apparatus in 6.8 pH phosphate buffer. From the in vitro drug release studies, F5 tablets showed 99.43±0.72% % drug release in 12 h and it followed zero order drug release. The mean dissolution time of all formulations was found to be 4.48 – 10.52 h and it was higher for formulations with ethyl cellulose when compared to HPMC K 15M due to its hydrophobic nature. Time in hours to take 80% drug release explained the ability of prolonged release and they were found to be 10.2 h for best formulation F5. From the stability study, similarity factor (f2) was found as 80.48, which is more than 50 indicates similarity between the dissolution profile before and after storage. Hence the development of Isradipine compression coated mini-tablets is a promising way to control the drug release as per therapeutic requirement.