Abstract

The present work aimed to enhance the water solubility of the hydrophobic drug, nimodipine, using a solid dispersion technique. Soluplus® as a novel hydrophilic polymeric carrier was used. Nimodipine-Soluplus® solid dispersions (1:10) were prepared by the conventional hot-melt (HM) method and impregnation method using supercritical fluid technology (SCF). The pure drug, physical mixtures, and the solid dispersions were characterized and compared. The solubility as well as the dissolution enhancement effects were studied. Solid dispersion by SCF technology showed 77 folds increment in nimodipine solubility, in comparison to only 48 folds when prepared by HM and 7.7 when physically mixed. Moreover, solid dispersion by SCF technology showed 4 folds increment in nimodipine dissolution rate, in comparison to only 3 folds when prepared by HM and < 5% when physically mixed. These results were attributed to the amorphous transfer of the drug inside the polymer matrix which was confirmed by powder X-ray diffraction and DSC. In addition to the hydrogen bonds formation between nimodipine and Soluplus® in the solid dispersion, that was obvious in the FTIR spectra; A weakening of nimodipine N–H stretching vibration of the secondary amine groups and C=O of ester group.

Key words: Nimodipine, solid dispersion, Soluplus®, supercritical fluid technology, dissolution.