Melt extrusion process for adjusting drug release of poorly water soluble drug felodipine using different polymer matrices.

The purpose of the present study was to use commercial available polymers like PVP/PEG, soluplus® and kollidon® SR to prepare immediate and sustained release formulations of felodipine by hot melt mixing method. Solid dispersions containing 5, 10, 20 and 30wt% drug have been prepared in a Haake-Buchler Reomixer at melt temperature 130°C and mixing time 10min. As was found from DSC and XDR studies completely amorphous and miscible solid dispersions can be prepared. In all cases a single glass transition was recorded, which is depended from the used drug amount. Hydrogen bonds and the molecular interaction between felodipine and polymer matrices are responsible for the miscibility of prepared formulations. This has as result the substantial enhancement of felodipine release rate in PVP/PEG mixture and due to the high solubility of used polymers immediate release formulations have been prepared. On the contrary, sustained release formulations can be prepared in the case of kollidon SR solid dispersions. The release mechanism of all preparations was studied using different kinetic models. Finally, binding affinity values calculated by molecular docking simulations were used as estimators for predicting long-term drug's physical stability in solid dispersions.