Studies on enhancement of solubility and dissolution properties of Nimodipine by solid dispersion technique

Nimodipine, a member of calcium channel blocker, specifically binds to L-type voltage-gated calcium channels. The maximum solubility of nimodipine was found at pH 1.2 and solubility decreases up to pH 4.0. At a pH 6.0 and higher pH, solubility reduces drastically. Suitable solid dispersion systems of nimodipine with PVP-K30 and maltodextrin were prepared by physical mixture, solvent evaporation and kneading methods at 1:1 and 1:3 drug: carrier. Drug content, saturation solubility, FTIR, and in-vitro dissolution were studied. The drug content was uniform, solubility of the drug increased linearly as a function of the carrier concentration and method. The FTIR studies indicates no chemical interaction between drug and polymer. The DP₆₀ and DE₆₀ values of solid dispersion systems prepared by solvent evaporation and kneading method were significantly higher (P<0.05) when compared to DP60 and DE60 values of physical mixture and pure Nimodipine. The dissolution follows first order model and obeyed Hixson- Crowell’s cube root law.