Abstract: In the Present study, nimodipine-PVP solid dispersion was investigated to enhance the dissolution rate of nimodipine (NMDP), a poorly water-soluble substance, and to formulate the dosage forms with fast-release properties. The dissolution properties of NMDP-PVP coprecipitate and physical mixture were compared. The physical states of NMDP in both newly-made and one-yak-old samples of solid dispersion were also investigated by X-ray diffraction analysis. The dissolution rate of NMDP from the tablets and capsules of coprecipitate was compared with that of two kinds of commercial tablets. The results showed that solid dispersion gave much higher improvement than Physical mixture in the dissolution rate. In 5 min, 89% of the ding was released from solid dispersion, and 45% from physical mixture. Powder X-ray diffraction pattern showed that NMDP was present in amorphous or molecular form in the solid dispersion while it was in crystal line form in physical mixture. There was no appearance of crystallization in solid dispersion after one-year storage in a sealed glass bottle under room temperature. Capsules and tablets of coprecipitate both showed fast-release properties, and the drug dissolution fate from the former was greater than that from the latter, suggesting that the compressing pressure could influence the dissolution rate. It was also demonstrated that the dissolution rate of NMDP from the selected capsules was much greater (about three to four times) than that from the two kinds of commercial tablets.

Key words: Nirnodipine, Solid dispersion, Fast-release formulation, Dissolution