Compounds in this category
Linaclotide (sold as Linzess) is a 14-amino-acid guanylate cyclase-C agonist approved by the FDA in 2012. It acts on intestinal epithelium, increasing chloride and bicarbonate secretion. Phase 3 trials in chronic idiopathic constipation and irritable bowel syndrome with constipation demonstrated improved bowel frequency and reduced abdominal pain across thousands of patients. The indication and dosing are defined.
Plecanatide (Trulance) has a similar mechanism and was FDA-approved in 2017. Both compounds are prescription-only and are not available as research chemicals. They appear in this category for completeness, not because they overlap with the research-peptide use cases readers usually ask about.
Teduglutide (Gattex) is a recombinant analog of glucagon-like peptide-2 (GLP-2). It is FDA-approved for short bowel syndrome in patients dependent on parenteral nutrition. Phase 3 data demonstrated reductions in parenteral support volume in both adult and pediatric populations. The drug requires injection and is administered under specialist supervision.
BPC-157 dominates online conversation about peptides and gut health. The compound is a 15-amino-acid sequence derived from a partial fragment of body protection compound, originally isolated from human gastric juice. Predrag Sikiric's group in Zagreb has published more than 100 rat studies since the early 1990s reporting accelerated repair of gastric ulcers, colitis lesions, and small-bowel anastomotic sites. Zero randomized controlled human trials on BPC-157 have been published. The compound is sold in the United States and the European Union as a research chemical under Research Use Only (RUO) labeling. It is not approved for human use by the FDA or EMA.
KPV is a C-terminal tripeptide fragment of alpha-MSH (alpha-melanocyte-stimulating hormone). Preclinical work in dextran sulfate sodium colitis mouse models has documented reduced inflammation markers and faster mucosal recovery. Human trials are absent. The compound is sometimes administered orally on the assumption that the small tripeptide survives gastric pH long enough to act on colonic tissue, which is mechanistically plausible and not pharmacokinetically confirmed in published clinical data.
Larazotide acetate is a tight-junction modulator originally developed for celiac disease. It progressed through Phase 2 trials showing reduced symptom burden in patients already adherent to a gluten-free diet but still symptomatic. The Phase 3 program faltered, and the drug is not currently approved in the US or EU. Larazotide is the closest peptide on this list to addressing the popular concept of "leaky gut" in a clinically defined patient population. The popular concept itself remains contested in mainstream gastroenterology.
VIP (vasoactive intestinal peptide) is endogenous to the human body, with a 28-amino-acid sequence. It modulates gut motility, secretion, and immune function. Synthetic VIP is investigational. Inhaled and injectable formulations have been studied for sarcoidosis and pulmonary indications. None of those programs targets gut health as a primary endpoint.
Two buckets, not one
Gut peptides separate into two distinct buckets. The FDA-approved drugs (linaclotide, plecanatide, teduglutide) have rigorous Phase 3 safety and efficacy data, defined indications, and require a prescription. The research peptides (BPC-157, KPV, larazotide) have varying degrees of preclinical and early clinical data, no FDA approval for any GI indication, and reach the consumer through grey-market channels that PeptScope does not endorse or link to.
Mechanism distinction
Some compounds in this category act on luminal epithelium (linaclotide, plecanatide). Some target tight junctions (larazotide). Some engage growth and repair pathways (BPC-157 preclinically, teduglutide clinically). Some modulate mucosal immunity (KPV, VIP). Reading rat data on BPC-157 colitis and assuming clean translation to human ulcerative colitis is not supported by the trial base. Where dosing is reported in each compound page, it is from the cited literature.