Secretin
/ Endogenous 27-residue gut peptide; secretin receptor (SCTR) agonist; foundational discovery hormone (Bayliss & Starling 1902)ALIAS · Synthetic human secretin · ChiRhoStim · SecreFlo
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Tier 1. Synthetic human secretin is FDA-approved as ChiRhoStim and SecreFlo for diagnostic use - stimulating pancreatic secretions during endoscopic retrograde cholangiopancreatography (ERCP) and as a provocative agent for secretin-stimulated MRCP and gastrinoma diagnosis. Famously the first hormone discovered (Bayliss and Starling 1902), founding the endocrine concept of 'hormone'.
Secretin is a 27-residue peptide of the secretin/glucagon superfamily released from S cells of the duodenum in response to acidic chyme. It binds the secretin receptor (SCTR), a class B G-protein-coupled receptor expressed primarily on pancreatic ductal cells, where Gs-mediated activation of adenylyl cyclase drives bicarbonate-rich aqueous secretion that neutralises gastric acid in the duodenum.
Secondary actions include modulation of gastric acid secretion, enhancement of cholecystokinin-stimulated pancreatic enzyme release, and effects on hepatic bile flow. The pancreatic ductal bicarbonate response is the basis for the diagnostic indication.
In clinical use, intravenous synthetic human secretin produces a rapid, reproducible pancreatic exocrine response that can be quantified by duodenal aspiration during endoscopy or by secretin-stimulated MR cholangiopancreatography (s-MRCP). In gastrinoma diagnosis, secretin paradoxically increases serum gastrin in patients with Zollinger-Ellison syndrome - the basis for the secretin stimulation test.
Tier 1 for the diagnostic indication. Synthetic human secretin (ChiRhoStim) holds FDA approval for stimulation of pancreatic secretions during pancreatic function testing, stimulation of pancreatic and biliary secretions to facilitate identification of the ampulla of Vater during ERCP, and gastrin secretion in suspected gastrinoma. Off-label use in autism (after a single 1998 case-series) generated controlled trials that did not support efficacy.
Intravenous synthetic secretin in diagnostic doses is generally well tolerated. Reported adverse effects are typically mild - flushing, nausea, abdominal cramping. Hypersensitivity reactions are rare. The diagnostic indication uses a single dose, so chronic-administration safety questions do not arise.
Regulatory status
- FDA status:
- FDA-approved
- Compounding:
- Not eligible for compounding (approved, not in shortage)
The secretin-for-autism episode (1998 case series suggesting symptom improvement after diagnostic secretin in autistic children) drove substantial off-label use and family interest; a series of well-controlled randomised trials in the early 2000s consistently failed to replicate benefit, and the indication was abandoned.
Compounding eligibility is 'not eligible' because the molecule is a marketed FDA-approved product without identified shortage. Vendor-sold 'secretin' research material does not interchange with the diagnostic product.