Sincalide (Kinevac)

Prescription

Sincalide (brand name Kinevac) is the synthetic C-terminal octapeptide of cholecystokinin (CCK-8) — the biologically active tail of the natural gut hormone cholecystokinin. CCK is released by the small intestine in response to fats and proteins and tells the gallbladder to contract and the pancreas to secrete digestive enzymes. Sincalide reproduces those actions on demand, which makes it a valuable diagnostic tool. Its best-known use is in nuclear medicine hepatobiliary (HIDA) scans. After a radiotracer is taken up by the liver and concentrated in the gallbladder, sincalide is infused to make the gallbladder contract, and imaging measures how much of its contents are expelled — the gallbladder ejection fraction (GBEF). A low ejection fraction supports a diagnosis of functional gallbladder disorder (biliary dyskinesia), helping explain biliary-type pain in people whose gallbladder looks normal on ultrasound. The rate of infusion matters: a slow, standardized 30- to 60-minute infusion gives more reproducible results than a rapid injection, which can cause cramping and falsely low values. Sincalide has additional diagnostic roles: stimulating pancreatic enzyme secretion for pancreatic function testing (sometimes together with secretin), promoting gallbladder emptying before certain imaging or to help clear retained contrast, and accelerating the transit of barium through the small intestine during radiographic studies. Mechanistically sincalide binds CCK-A (CCK1) receptors on gallbladder smooth muscle and pancreatic acinar cells, triggering contraction and enzyme secretion. Because it is a potent stimulant of gut smooth muscle, transient abdominal cramping, nausea, or an urge to defecate can occur, especially with faster infusions. It is given by clinicians during imaging studies, and results are interpreted alongside symptoms and other findings.