Abstract: Aim To prepare a solid dispersion of cisapride with hydroxypropylmethyl cellulose (HPMC E5 LV) as carrier for the purpose of accelerating the in vitro drug release by means of improving the solubility of the model drug. Methods Alcohol and simulated gastric fluid (SGF) were used to dissolve cisapride and HPMC in order to make the model drug dispersed homogeneously in the carrier. The HPMC-cisapride solid dispersion was then obtained by conventional solvent evaporation method. Powder X-ray diffraction (XRD) was used to measure the diffraction peaks of pure carrier, pure cisapride, physical mixture of HPMC with cisapride (4:1), and HPMC-cisapride solid dispersion (4:1) to confirm the crystal existence. The solubility of pure drug and HPMC-cisapride solid dispersion was measured with water, SGF and simulated intestinal fluid (SIF). The in vitro drug releases of the sustained release tablet prepared with pure cisapride or HPMC-cisapride solid dispersion were investigated with water and SGF as media, respectively. Results No diffraction peaks were found by X-ray diffraction in the HPMC-cisapride solid dispersion (4:1), indicating that the drug existed in an amorphous form at that drug-carrier ratio. Compared with the pure drug, the solubilities of HPMC-cisapride solid dispersion are increased by 239.4% in SGF, 132.6% in water, and 117.9% in SIF. According to the in vitro drug release, the sustained release tablet prepared with HPMC-cisapride solid dispersion had a faster drug release than did that prepared with pure drug. The in vitro drug release profiles were found to comply with Higuchi's rule. Conclusion The in vitro drug release of the sustained release tablet made by HPMC-cisapride solid dispersion is improved owing to the increased drug solubility.

Key words: cisapride, cisapride, HPMC E5 LV, HPMC E5 LV, solid dispersion, solid dispersion