Factors effecting the morphology of Eudragit S-100 based microsponges bearing dicyclomine for colonic delivery

The purpose of this study was to design microsponge-based novel colon-specific drug delivery system bearing dicyclomine. Eudragit S-100-based microsponges containing the drug in varying amount were prepared using quasi-emulsion solvent diffusion method. The microsponges were prepared by optimizing various process parameters. Differential scanning calorimetry and Fourier transform infrared studies indicated compatibility and stability of the drug in various formulations. Shape and surface morphology of the microsponges were examined using scanning electron microscopy. The formulations were subjected to in vitro release studies, and the results were evaluated kinetically and statistically. In vitro release data showed a biphasic pattern with an initial burst effect. In the first hour, drug release from microsponges was found to be between 17% and 31%. The cumulative percent release at the end of eighth hour was noted to be between 53% and 83%. The release kinetics showed that the data followed Higuchi model and the main mechanism of drug release was diffusion. The colon-specific tablets were prepared by compressing the microsponges followed by coating with pectin:hydroxypropylmethylcellulose mixture. In vitro release studies exhibited that compression-coated colon-specific formulations started releasing the drug at the sixth hour corresponding to the arrival time at colon. The study presents a new approach for colon-specific drug delivery.