Formulation and Evaluation of Cilnidipine Solid Dispersions and Oral Controlled Release Tablets

Drug solubility plays an important role in the improvement of bioavailability. Biopharmaceutical Classification System (BCS) Class-II drugs have less solubility and more permeability. Most of the drugs available in the market belong to BCS class-II. The objective of the present study is to improve the solubility of BCS Class-II drug, Cilnidipine by formulating them as solid dispersions and to make controlled release formulations. Solid dispersions of Cilnidipine were prepared by solvent evaporation technique using plasdone K29/32. Various physical parameters were evaluated for the prepared solid dispersions. The in vitro drug release studies were performed for the solid dispersions using phosphate buffer pH 6.8. The solid dispersions which showed maximum drug release were selected for the preparation of oral controlled release formulations. Tablets were prepared using Cilnidipine solid dispersions and varying concentrations of polyethylene oxide (PEO) WSR 303 by direct compression technique. Pre and post-compression parameters were evaluated along with in vitro drug release studies. In vitro dissolution studies revealed that solid dispersion CP3 containing Cilnidipine and plasdone K29/32 in 1:3 ratios showed faster drug release in a short time. The pre and post compression parameters of the solid dispersions and tablets were within specified limits. Formulation CPP5 containing CP3 solid dispersion with 25% w/w of PEO WSR 303 showed prolonged drug release up to 12h. Similar drug release was also obtained with CPP6 formulation having 30%w/w of PEO WSR 303. The present study prepared a novel Cilnidipine pharmaceutical product having increased solubility and prolonged drug release which is not available in the market. The solubility of Cilnidipine was enhanced using plasdone K-29/32 and the drug release was delayed using PEO WSR 303 as polymer. This could be advantageous to many of the patients with cardiovascular disorders