Preparation of Ethylcellulose Coated Gelatin Microspheres as a Multiparticulate Colonic Delivery System for 5-Aminosalicilic Acid

In the long-term management of ulcerative colitis patients, repeat dosing maybe required. Since 5-ASA is largely absorbed from the upper intestine, selective delivery of drugs into the colon may be regarded as a better method of drug delivery with fewer side effects and a higher efficacy. The aim of this study was to prepare and evaluate a double coated multiparticulate system for 5-ASA delivery using gelatin and ethylcellulose as the primary and secondary polymer respectively. Gelatin microspheres containing 5-aminosalicylic acid was produced using the solvent evaporation method. Prepared gelatin microspheres were spherical, free flowing, non-aggregated and showed no degradation in the acidic medium. Entrapment efficacy of microspheres was about 50%. Results showed that drug release was fast and complete and is affected by the amount of core material entrapped. Gelatin microspheres were then coated by ethylcellulose using a coacervation phase separation technique. The idea for this approach was to prepare a delayed drug delivery system, in which, ethylcellulose protects particles for the first 6 h transit through the gastrointestinal tract. However, it was shown that this system could provide a suitable drug release pattern for colonic delivery of active agents, as 30% of the drug was released from the ethylcellulose-coated microcapsules within 6 h, while this amount was 90% of the loaded drug for gelatin microspheres under the same condition.