PL8177_Dosage, benefits & legal status
Also known as PL-8177, Ac-Nle-cyclo-(Glu-His-D-Phe-Arg-Dap)-Trp-NH2
A melanocortin peptide built around the same core as PT-141, aimed at the gut wall instead of the brain.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is PL8177?
Plain language first. The technical label stays, but it never stands alone.Overview
It carries the same His-D-Phe-Arg-Trp core as PT-141 and Melanotan II, but its ring is rearranged so that it hits one receptor, and it is swallowed rather than injected, with the capsule engineered to open in the colon. A trial in active ulcerative colitis was planned for up to 28 patients and stopped at 12 when the company shifted resources to obesity drugs.
PL8177 is a cyclic heptapeptide selective for the melanocortin-1 receptor, with the published structure Ac-Nle-cyclo-(Glu-His-D-Phe-Arg-Dap)-Trp-NH2. Palatin formulated it in a capsule designed to release the peptide at the intestinal wall rather than absorb it, so the drug acts locally on inflamed bowel.
What it's used for
An investigational oral capsule for ulcerative colitis. It is not approved and is not sold. The company also holds an orphan designation for it in a form of eye inflammation.
How does PL8177 work?
What it does in the body, and where.Melanocortin receptors come in five types. MC4R drives appetite, MC1R drives pigment in skin, and both also sit on immune cells. PL8177 goes after MC1R for the second reason rather than the first.
- 01The same core, a different targetHis-D-Phe-Arg-Trp is the four-residue core that melanocortin drugs are built around. In PT-141 and Melanotan II all four sit together inside the ring. PL8177 breaks that pattern: its ring runs from a glutamic acid to a diaminopropionic acid and holds His, D-Phe and Arg, while the tryptophan sits outside the ring on the far side of that diaminopropionic acid. Both ends are capped, with an acetyl group on a norleucine at one end and an amide at the other. That rearrangement is what makes it selective for MC1R rather than the receptors its relatives hit.
- 02Switching MC1R on calms immune cellsActivating MC1R on immune cells in tissue reduces inflammatory signaling. That is the anti-inflammatory arm of the melanocortin system, separate from pigment and from appetite.
- 03Delivered to the bowel wall, not the bloodstreamThe capsule is built to release the peptide where the inflammation is. A peptide swallowed as a plain powder would be digested, so the formulation is as much the invention as the molecule.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
What the 12-patient trial reported
Investigational- Human trialNine patients received PL8177 and three received placebo, once daily by mouth for 8 weeks.
- Human trialClinical remission was 3 of 9 against 0 of 3, and symptomatic remission 5 of 9 against 1 of 3.
- No dataClinical response was 7 of 9 against 1 of 3, reported at p<0.005. The same release states that because of the low patient numbers the study was not powered to show statistical significance.
- No dataThe endoscopic figures quoted came from a 5-patient subset of people with inflammation in all three colon segments at baseline, against a single placebo patient.
- Human trialNo treatment-related side effects were reported.
What the registry asked for
Investigational- RegulatoryThe registered second primary endpoint is the proportion of patients reaching a Mayo endoscopic subscore of 1 or 0 at week 8, across the randomized group.
- No dataThat whole-group endoscopic result has not been reported. What was reported instead is a post hoc subset of five patients scored segment by segment.
- RegulatoryThe trial was planned for up to 28 patients with an interim look after 12 to 16. Enrollment stopped at 12 because the company moved resources to out-licensing talks and its obesity programs, not because of a safety or futility finding.
The p<0.005 attached to the clinical response result comes from a trial of 12 people whose own sponsor wrote, in the same release, that it was not powered to show statistical significance. Those two statements sit side by side and the first is usually quoted without the second. The endoscopic improvement figures are from a five-patient subset, not from the registered endoscopic endpoint, and that registered endpoint has not been reported. PL8177's FDA orphan designation is for a form of eye inflammation, not for ulcerative colitis, and an orphan designation is not an approval. The trial also stopped for business reasons rather than because anything went wrong.
The published record
Papers and trials about PL8177
4 papers tagged human · 3 not reviews or lab · 0 clinical trial publications
1 registered trials · none with posted results
Furthest stage reached: Phase 2, under way
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count.
At a glance
Four things to know about PL8177
Evidence
Investigational
Category
Healing and recovery
Common vial
Varies
Half-life
Not published
How much, and do you cycle it?
The range, and whether you take breaks.Dose not disclosed; taken once daily for 8 weeks in the trial, once daily. Daily for 8 weeks in the trial Trial dose
The trial gave it once daily for 8 weeks with safety followed to week 12. No longer-term schedule has been tested.
Not publishedNo figure
No pharmacokinetic figures have been published. The formulation is designed to release the peptide at the bowel wall rather than to be absorbed, so a blood half-life is not the number that matters for it.
You can compare this against the whole library to see where it sits.
What does it cost?
Typical dose and cost, in plain numbers.PL8177 is not injected
It is taken by mouth (colon-release capsule). Neither the registry nor the results release states the dose. What is known is that it was taken by mouth once daily for 8 weeks in patients whose bowel inflammation scored at least 2 on the Mayo endoscopic scale. No dose exists outside that trial.
How do you store it?
Before mixing, and after.Room temperature. Cool, dry, out of light.
PL8177 is taken as a pill or capsule. Keep it in its original container at room temperature, away from heat, humidity, and direct sun. No fridge or mixing needed. Check the expiration date on the bottle.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Any use outside a trial: no product exists and nothing is sold
- Treating ulcerative colitis with anything bought as a research peptide, given this capsule's whole design is a colon-release formulation that a powder cannot reproduce
Stop and get help
- Not applicable outside a trial
Common effects
- None reported as treatment-related, in a trial of 12 people
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is PL8177 approved?
And where the numbers on this page come from.No. PL8177 is not approved anywhere and is currently in company-run clinical trials. There is no legal route to obtain it outside a trial.
- Approval statusInvestigational
- RouteBy mouth (colon-release capsule)
- Checked23 October 2026
- DoseFrom published clinical trials. Not approved by a regulator for this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Sources
What has happened recently
Not approved anywhere. The ulcerative colitis trial (NCT05466890) is registered as a phase 2 study, status active not recruiting, with 16 participants estimated, started September 15, 2022 and a primary completion date of February 10, 2025. Its registered endpoints are safety through week 12 and the share of patients reaching a Mayo endoscopic subscore of 1 or 0 at week 8. The FDA granted PL8177 orphan drug designation on June 3, 2019 for non-infectious intermediate, posterior, pan and chronic anterior uveitis, not the bowel indication; that designation is not an approval and the record lists it as not approved for the orphan indication. FDA substance record UNII 16134B0YTH, CAS 1309111-58-7.
You can compare this against the whole library, or read how to check a seller.
What else is like PL8177?
Others in Healing and recovery, side by side.If you're weighing PL8177, it's worth reading PL9643, Plecanatide (Trulance), and Redasemtide in the same class.
A melanocortin peptide built around the same core as PT-141, aimed at the gut wall instead of the brain.
- Dose
- Dose not disclosed; taken once daily for 8 weeks in the trial
- How often
- Once daily
An investigational eye drop whose phase 2 missed both primaries outright, whose phase 3 result depends on which analysis you read, and which its developer has now licensed out.
- Dose
- 1 microgram per mL, one drop in each eye, in the published phase 2
- How often
- Three times daily (phase 2 schedule)
A daily constipation tablet that works inside the gut and barely reaches the blood.
- Dose
- 3 mg once daily (label)
- How often
- Once daily, with or without food
An experimental IV peptide meant to recruit your own stem cells, tested in skin disease, stroke and liver disease.
- Dose
- 0.75 to 1.5 mg/kg daily for 5 days, or weekly (trial doses)
- How often
- Daily for 5 days, or weekly for 4 weeks (trials)
Guides for this compound
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
- How to Read a Peptide COA
What the purity number does and does not tell you, and how to spot an edited report.
- How to Vet a Peptide Vendor
Independent COAs, HPLC purity, and the red flags that mean walk away.
Sources
- FDA GSRS substance record, PL-8177 (UNII 16134B0YTH)(2026)Cyclic peptide, molecular formula C48H65N15O9, molecular weight 996.13, CAS 1309111-58-7. The record carries a structure but no residue sequence field.
- FDA orphan drug designation record for PL8177(2019)Lists the generic name as Ac-Nle-cyclo-(Glu-His-D-Phe-Arg-Dap)-Trp-NH2, designated June 3, 2019 to Palatin Technologies for non-infectious intermediate, posterior, pan and chronic anterior uveitis. Status designated, not approved for the orphan indication.
- PL8177 ulcerative colitis trial record, ClinicalTrials.gov NCT05466890(2025)Phase 2, active not recruiting, 16 participants estimated, started September 15, 2022, primary completion February 10, 2025. Primary endpoints are safety through week 12 and the proportion reaching a Mayo endoscopic subscore of 1 or 0 at week 8.
- Palatin phase 2 topline results, March 28, 2025(2025)12 patients randomized, 9 to PL8177 and 3 to placebo, once daily by mouth for 8 weeks. Clinical remission 3 of 9 against 0 of 3; clinical response 7 of 9 against 1 of 3 at a reported p<0.005. Enrollment stopped at 12 of a planned 28, and the release states the study was not powered to show statistical significance.
Beyond these, 6 records are indexed. Browse the records