Di- and tripeptidyl peptidases (EC 3.4.14.-) make up an individual class of aminopeptidases. Butabindide oxalate (Axon 1228) has proven to inhibit the cholecystokinin-8 (CCK-8)-inactivating peptidase, which is in fact a membrane-bound isoform of tripeptidyl peptidase II (EC 18.104.22.168). CCK-8 in its sulfated form functions as a neurotransmitter. It is released in response to ingestion of food and is involved in the control of food digestion through regulation of gallbladder contraction, pancreatic secretion, and contraction of the pyloric sphincter to delay gastric emptying. Inhibition of the enzyme therefore could be an opportunity to treat obesity related metabolic diseases.
 Inhibitors of Tripeptidyl Peptidase II. 3. Derivation of Butabindide by Successive Structure Optimizations Leading to a Potential General Approach to Designing Exopeptidase Inhibitors. C.R. Ganellin et al. J. Med. Chem., 2005, 48, 7333-7342.