Development and Evaluation of Hydrophobic Carriers Based Sustained Release Diltiazem Hydrochloride Formulations by Various Techniques and Its Comparison

The aim of present work is to study the release of diltiazem hydrochloride from tablets with ethyl cellulose (EC), eudragit RSPO and kollidon SR in different drug-to-polymer ratios were investigated with a view to develop twice-daily sustained release dosage form by polymeric dispersion (PD) technique. The polymeric dispersions containing ehtyl cellulose, eudragit RSPO or kollidon SR at drug-polymer ratios of 1:0.5, 1:1, 1:1.5, 1:2, with diltiazem hydrochloride were developed using solvent evaporation technique and co precipitation technique. The physical mixtures of drug and polymers were prepared by using simple mixing technique at the same ratio. The study of FTIR could not show significant interaction between diltiazem HCl and ethyl cellulose or kollidon SR or eudragit RSPO. Prepared tablets were evaluated for the release of diltiazem Hydrochloride over a period of 12 h in pH 7.4 phosphate buffer using US Pharmacopoeia type II dissolution apparatus. The in vitro drug release study revealed that the tablets prepared by dispersion technique have extended the release rate for 12 h whereas the tablets prepared by physical mixing technique at the same concentration have extended the release rate only up to 8 h. The in vitro release profile and the mathematical models indicate that release of diltiazem Hydrochloride can be effectively controlled from a tablet containing polymeric dispersion of eudragit RSPO.