Chem. Pharm. Bull. 55(7) 975—979 (2007)

drug-containing suspension and/or solution. They are useful in preparing pellets with a uniform drug content as well as for producing a modified release solid oral dosage form. Even though a variety of polymeric coating techniques have been developed, one popular method relies on the use of a fluidized bed coater. Several studies have focused on the critical process variables as well as their effects on the characteristics of the pellets. However, one limitation associated with a film, particulate and/or pellet coating is the failure to tailor the release patterns of poorly water-soluble drugs due to their limited aqueous solubility. Therefore, a variety of solubilizers including polyethylene glycol and surfactants have been used to improve the aqueous solubility before the coating process. Cisapride has been used to treat adult patients with nocturnal heartburn due to gastroesophageal reflux disease but safety issues have restricted its use in many countries. However, it is still used widely to treat motility disorders in small animals such as dogs and cats. In this study, we prepared and optimized cisapride-loaded sugar spherical pellet formulations for sustained release. Cisapride was chosen as a model compound, on account of its peculiar solubility behavior: it is slightly soluble at an acidic pH but virtually insoluble in water and at a physiological pH. It was expected that a combination of solubilization and polymeric coating techniques could modify the release pattern of cisapride. In order to achieve these objectives, cisapride-loaded pellets were prepared with different formulations. Their dissolution patterns were investigated in the simulated gastric and intestinal fluids. The surface morphology and cross section of the dual drug-loaded pellets were also visualized using scanning electron microscopy (SEM). Finally, after administering the pellets orally to dogs, the pharmacokinetic parameters of the cisapride-loaded sugar spheres were compared with those of a marketed tablet.