Strategy for large intestinal mucosa targeting by suppositories dispersing microcapsules contained 5-aminosalicylic acid

Eudragit L and/or RS microcapsules contained 5-aminosalicylic acid (5-ASA) were prepared. The microcapsules having pariticle sizes in the region of 53-150 μm were dispersed into Witepsol S-55 which has been known to be distributed uniformly from rectum to colon after rectal administration. In in vivo evaluation using rats, the plasma concentration-time profiles of 5-ASA obtained after rectal administrations of suppositories dispersing microcapsules showed clearly sustainedreleasing and maintained 5-ASA concentration at almost constant levels 12h after administration. The microcapsules containing 5-ASA in suppositories were widely distributed from upper rectum to colon and higher residual percentages of 5-ASA in large intestinal lumens were obtained compared with the conventional suppositories contained 5-ASA powder.