Comparison of methods to improve the dissolution rate of nitrendipine

Purpose: Nitrendipine, a dihydropyridine calcium antagonist, was used as a poorly water-soluble model drug to compare several methods of improving its dissolution rate. Methods: Nitrendipine dispersions were prepared by micronization, solvent deposition, the solvent evaporation method, and the solvent evaporation-deposition method. The drug dissolution rate and the physicochemical properties of these solid dispersions were investigated and compared using dissolution tests, X-ray diffraction analysis (XRD) and differential scanning calorimetry (DSC). Results: The dissolution rate of nitrendipine was greatly improved in disper-sions, particularly in the solid dispersions prepared by the solvent evaporation-deposition method, in which nitrendipine was present in amorphous form and the percentage of nitrendipine dissolved in the first 10 min was more than 80%. Conclusion: The nitrendipine dissolution rate is greatly improved when its solid dispersions were prepared by the solvent evaporation-deposition method.

Keywords: Nitrendipine Solid dispersion Solvent evaporation-deposition method Dissolution test