Development of Extended Release Matrix Tablets of Felodipine Through Solid Dispersions for Better Drug Release Profile by a 32 Factorial Design

Felodipine extended release matrix tablets with slow initial release and long action are suitable for once daily administration and might be good substitutes for immediate acting calcium channel blockers to minimize the risk of myocardial infarction. The aim of the present study are to prepare felodipine extended release matrix tablets through forming solid dispersions of the drug followed by wet granulation technique and also to study the influence of polymers on the release rate of the drug. The drug excipients compatibility was confirmed by Fourier transmission infrared spectroscopy and Differential Scanning Calorimetry studies. The solid dispersions, with an enteric polymer Eudragit L 100, and then the matrix tablets with hydroxypropyl methyl cellulose K4M were prepared. Here, a 32 factorial design of response surface method was employed to study the influence of the two polymers at 3 levels by design of experiments. The influence on the release rate constant was studied by response surface plots and Analysis of Variance. The drug release pattern from formulation F8, with a release of 87.84 % after 8 hrs, was complied with the dissolution criteria of test 2 of USP 35 and NF 30. The results of dissolution kinetics indicated that the selected model and the factors were significant at polynomial quadratic order.