ABS-16 is a novel treatment for Ulcerative Colitis. It is a single molecule with mutual pro-drugs of individual drugs, one of which is different than the pro-drug in ABS-15. The active moieties are well known and have an excellent safety record. The unique molecule consists of a non-absorbed salt of an analgesic that is not active in its ingested form. It is broken down by bacteria in the colon into the effective ingredients. This approach allows maximum exposure of the drugs to the affected tissue while minimizing systemic exposure and their associated side effects. The drug is dosed as sustained release pellets that are enteric coated so they move into the ileum before the drug begins to release. The release patterns of the pellets are optimized to deliver the drugs over a 12 to 24 hour period.