CCK/gastrin antagonists--clinical perspectives.

There are (at least) two types of receptor for cholecystokinin (CCK)/gastrin peptides. Highly potent specific antagonists are available for both types. The CCKA-receptor mediates classical CCK-like effects on the gut. Antagonists given to man inhibit pancreatic enzyme secretion and generally shorten gastrointestinal transit times. Potential clinical indications include anorexia, gastro-paresis, pseudo-paresis, pseudo-obstruction, severe constipation and chronic pancreatitis. However gallbladder contraction is markedly inhibited and this led to gallstone formation in baboons. This will obviously have to be avoided if CCKA antagonists are to be used in man. CCKB-receptors mediate the effects of gastrin on the gut and the effects of CCK in the brain. They inhibit gastrin-stimulated acid secretion. If used in acid-peptic disease they might inhibit the trophic effects of gastrin on enterochromaffin cells. CCKB-antagonists can also inhibit the growth of some gastrin-dependent tumours, including certain human colonic cancer cell lines which produce gastrin. CCKB-antagonists have a potent anxiolytic-like effect in animals, and this effect might become their main clinical application.