Sincalide ammonium (Cholecystokinin octapeptide ammonium, CCK-8 ammonium) is a rapid-acting amino acid polypeptide hormone analogue of cholecystokinin (CCK) for intravenous use in postevacuation cholecystography. Sincalide ammonium is a major bioactive segment of CCK that retains most of the biological activities of CCK. CCK‐8 can promote gallbladder contraction by injection and helps diagnose gallbladder and pancreas disorders. Sincalide ammonium can increase bile secretion, cause the gallbladder to contract and relax the sphincter of Oddi, resulting in bile drainage into the duodenum. Sincalide ammonium is a major bioactive segment of CCK that retains most of the biological activities of CCK.