Sincalide: Mechanism, Dosing & Research Data

Sincalide (Kinevac) is the synthetic C-terminal octapeptide of cholecystokinin (CCK-8-sulfate), the biologically active fragment of native CCK. It is FDA-approved for IV use to stimulate gallbladder contraction (cholecystokinin cholescintigraphy), stimulate pancreatic secretion for function testing, and accelerate transit of barium during intestinal radiographic studies.

Mechanism of Action

CCK1R on gallbladder smooth muscle: Gq/11/PLC/IP3-mediated contraction; gallbladder ejection fraction measurable by hepatobiliary scintigraphy
CCK1R on pancreatic acinar cells: stimulates digestive enzyme secretion (lipase, amylase, trypsinogen, chymotrypsinogen)
CCK1R on Oddi sphincter: causes relaxation, allowing bile and pancreatic juice to flow into duodenum
Vagal afferent activation via CCK1R in gut wall: sends satiety signals to brainstem (nucleus tractus solitarius)
Pylorospasm at high doses (CCKB/gastrin receptor activation): causes abdominal cramping characteristic of sincalide diagnostic use

Research Findings

Cholecystokinin cholescintigraphy: sincalide 0.02 mcg/kg IV over 3-10 minutes reduces GBEF (gallbladder ejection fraction) below 35% in biliary dyskinesia; >80% sensitivity/specificity for sphincter of Oddi dysfunction
Pancreatic function test: sincalide + secretin combination produces duodenal aspirate for lipase, amylase, bicarbonate quantification; gold standard for exocrine pancreatic insufficiency
Gallbladder ejection fraction: normal GBEF >35-40% at 30 minutes after sincalide infusion; values <35% associated with biliary dyskinesia and improved with cholecystectomy
Satiety research: sincalide IV reduces food intake in healthy volunteers; used to study CCK satiety signaling and develop CCK analogs for obesity
Functional dyspepsia: sincalide provocation of symptoms during HIDA scan helps identify functional gallbladder disease vs organic pathology

Research Protocols

Gallbladder ejection fraction (FDA-approved): 0.02 mcg/kg IV over 3-10 minutes concurrent with HIDA scan imaging; slow infusion reduces side effects
Pancreatic function testing: 0.02 mcg/kg/hr IV infusion for 1 hour + secretin 1 U/kg IV; aspirate duodenal contents for enzyme/bicarbonate analysis
Accelerated intestinal transit: 0.04 mcg/kg IV in single dose to accelerate barium through small bowel during radiography
Research satiety studies: 0.01-0.08 mcg/kg IV in dose-response assessment of food intake and nausea thresholds

Interactions

Secretin: synergistic for pancreatic function testing; combined sincalide/secretin test maximizes sensitivity for exocrine insufficiency
Morphine and opioids: reduce CCK-driven GI motility; may blunt sincalide-mediated gallbladder contraction during HIDA scan (acute care consideration)
Atropine: anticholinergic blocks some gallbladder motor response to sincalide; avoid during HIDA scan

Safety Profile

FDA-approved diagnostic peptide. Common: abdominal pain/cramping (reproduced biliary-type pain), nausea, dizziness during infusion. Slow infusion (over 10 min) dramatically reduces side effects vs bolus. Rare: hypotension, bradycardia. Contraindicated in complete biliary obstruction (risk of bile duct rupture).