Plecanatide is a prescription drug, not a gray-market research peptide. It sells under the brand name Trulance and the FDA approved it in January 2017 for chronic idiopathic constipation (CIC) in adults, then in January 2018 for irritable bowel syndrome with constipation (IBS-C). It was developed by Synergy Pharmaceuticals, originally under the code SP-304.
Chemically it is a small cyclic peptide, 16 amino acids, that copies human uroguanylin almost exactly. The one change is at position 3, where the natural aspartate is swapped for glutamate. That single substitution is what the CAS-registry alias "(3-Glutamic acid(D>E)) human uroguanylin" refers to. The tweak makes the peptide more stable and active in the slightly acidic environment of the upper small intestine.
How it works
Plecanatide is an agonist of guanylate cyclase-C (GC-C), a receptor sitting on the cells that line the intestinal lumen. When the peptide binds GC-C, the cells crank up cyclic GMP (cGMP). Elevated cGMP drives chloride and bicarbonate out into the gut through the CFTR channel, water follows, stool softens, and transit speeds up. Because it acts on the luminal surface and is barely absorbed into the bloodstream, its effect stays in the gut. The FDA-approved drug guidance for prescribers describes this same local, fluid-secretion mechanism.
If the design sounds familiar, it is closely related to linaclotide (Linzess), another GC-C agonist for the same conditions. The pitch for plecanatide is that it mimics uroguanylin, which is normally most active in the acidic proximal small bowel and quiets down as pH rises, a pattern its makers argued might reduce diarrhea.
What the trials found
The evidence base here is real and peer-reviewed, four Phase 3 randomized, placebo-controlled trials across CIC and IBS-C.
In the pivotal CIC trial reported by Miner and colleagues in the *American Journal of Gastroenterology* (2017), 1,394 adults took plecanatide 3 mg, 6 mg, or placebo once daily for 12 weeks. The primary endpoint was a "durable" complete spontaneous bowel movement (CSBM) responder, meaning at least 3 CSBMs a week with one or more added over baseline, for at least 9 of 12 weeks. Both doses beat placebo: 21.0% (3 mg) and 19.5% (6 mg) were durable responders versus 10.2% on placebo. The most common side effect was diarrhea, in about 5.9% (3 mg) and 5.7% (6 mg) of patients versus 1.3% on placebo.
Reviews summarizing the program reach the same conclusion across both indications, modest but statistically clear improvements in bowel-movement frequency and, in IBS-C, abdominal pain, with diarrhea as the main adverse event. A useful overview is the Trulance review in *P&T / PMC* (2018).
Regulatory and safety status
Plecanatide is an approved drug, so the regulatory picture is well defined. The label carries a boxed warning: it is contraindicated in patients under 6 years of age because of a risk of serious dehydration, a finding driven by deaths in juvenile mice. Safety and effectiveness have not been established in children 6 to under 18. It is also contraindicated when mechanical gastrointestinal obstruction is known or suspected. The approved dose is 3 mg once daily.
It is a peptide therapeutic taken by mouth, not a banned performance substance, and it has no recognized doping application; it is not a focus of WADA's prohibited list.
Buyer and quality note
Because plecanatide is an FDA-approved oral drug dispensed by pharmacies under the Trulance brand, it does not behave like the typical research-only peptide sold in vials with a certificate of analysis. There is no legitimate "research use only" lyophilized-powder market for it the way there is for experimental compounds. If you encounter plecanatide powder being sold outside a pharmacy, treat identity and purity claims with heavy skepticism, third-party COAs for an approved small-molecule-like peptide are not a substitute for a regulated supply chain.
This page aggregates public information and is not medical or dosing advice. Plecanatide is a prescription medication; decisions about it belong with a licensed clinician.