Abstract: Nimodipine (NMDP) sustained release formulations were designed with hydroxypropyl methylcellulose (HPMC) as swellable polymer and with solid dispersion of the drug in polyvinyl pyrrolidone (K30), a water-soluble system, and compressed into tablets by direct compression. Drug release kinetics from tablets with different compositions was investigated in vitro. Results showed that dissolution process of NMDP from porous hydrophilic matrix conformed to zero-order release kinetics. The addinon of microcrystalline cellulose to the porous swellable release system increased the NMDP release rate constant. The presence of hydroXyethylcellulose (HEC) in the system, which had a lower viscosity, increased the drug release rate constant. When tablets were prepared with HPMC 40 mesh granulation, the release rate of the drug was sustained. These show that the dosage form may be formulated as a drug-polymer system with constant release at a desired rate. The release properties of the sustained release tablets made by pure drug instead of drug solid dispersion were also investigated. In the present study, the optimal formulations that constantly released the drug during 12 h were selected for in vivo analysis.

Key words: Nimodipine, Nimodipine, Hydroxypropyl methylcellulose, Sustained release tablets, Solid dispersion,Release kinetics, Hydroxypropyl methylcellulose, Sustained release tablets, Solid dispersion,Release kinetics