Preparation, Characterization, and In Vitro Evaluation of Nitrendipine Solid Dispersions

Abstract

In order to enhance the absorption of dissolution rate of nitrendipine (NIT), solid dispersions were prepared using two water soluble carriers, polyvinylpyrrolidone K30 (PVP K30) and polyethylene glycol 4000 (PEG-4000), by solvent and fusion method. The dissolution profile of solid dispersions were compared to the pure drug in both pH 1.2 hydrochloric acid and pH 6.8 phosphate buffer and the results have shown profound improvement in drug release. The solubility of solid dispersion was increased by several folds when compared to pure NIT. The physicochemical properties of the solid dispersions were examined using analytical techniques. The results of microscopic studies, x-ray powder diffraction (XRPD), and differential scanning calorimetric (DSC) analysis confirmed the amorphous state of solid dispersion in comparison to the crystalline nature of pure drug, proposing that NIT was molecularly dispersed in the polymer matrices, which were accounted for by dissolution rate enhancement. Fourier transform infrared (FTIR) spectroscopic analysis indicated the presence of hydrogen bonding between NIT and the polymers, which also explained the improvement in solubility and dissolution rate. In conclusion, solid dispersion of NIT with PVP K30 and PEG-4000 improved the solubility and rate of dissolution, which may improve the absorption of the drug and subsequently the bioavailability of NIT.