PT-141 (Bremelanotide): The Desire Scores Moved, the Satisfying Sexual Events Did Not

PT-141 is FDA-approved. Bremelanotide cleared review as VYLEESI on 21 June 2019, and its two pivotal trials moved questionnaire scores by about three-tenths of a point while the endpoint counting actual sexual encounters did not move at all.

That combination — a genuine regulatory pedigree attached to a thin behavioural result — makes bremelanotide the most instructive compound in the libido and sexual wellness peptides category, and one of the hardest to verify in a vial: it sits roughly one dalton from melanotan II, which is approved nowhere in the world.

Did PT-141 increase satisfying sexual events?

No. In RECONNECT, two identical phase 3 trials of 1,267 premenopausal women over 24 weeks, bremelanotide moved both co-primary questionnaire endpoints by roughly 0.3 points more than placebo, at p-values from 0.0053 to below 0.0001. On satisfying sexual events — the only endpoint counting actual encounters — FDA's label states there was "no significant difference between treatment groups." Both findings come from the same regulatory document.

The pivotal evidence is Kingsberg et al. (Obstetrics & Gynecology, 2019;134(5):899–908, PMID 31599840), reporting NCT02333071 and NCT02338960: randomised, double-blind, placebo-controlled, 24 weeks.

Co-primary endpoint 1 — FSFI Desire Domain score:

Co-primary endpoint 2 — FSDS-DAO Question 13 (distress from low desire):

Both endpoints hit statistical significance. Both are questionnaire scores, and the treatment differences are roughly 0.3 points on scales where the clinical meaning of three-tenths of a point is not self-evident. Section 14 of FDA's label then records the behavioural result in one sentence: "There was no significant difference between treatment groups."

So the drug made women rate their desire slightly higher and their distress slightly lower, and did not measurably change how much satisfying sex they had over six months. That is the complete efficacy picture, and it comes from FDA's own document rather than from any critic's summary.

What is VYLEESI approved for, and what does the label rule out?

VYLEESI is approved for acquired, generalised hypoactive sexual desire disorder in premenopausal women only, under NDA 210557, granted 21 June 2019 and currently marketed by Cosette Pharmaceuticals. FDA's Limitations of Use are two sentences long: it is "not indicated for treatment of HSDD in postmenopausal women or in men," and it is "not indicated to enhance sexual performance." That second sentence excludes essentially the entire grey-market use case.

The indication, in FDA's exact words: "VYLEESI is indicated for the treatment of premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD), as characterized by low sexual desire that causes marked distress or interpersonal difficulty and is NOT due to: A co-existing medical or psychiatric condition, Problems with the relationship, or The effects of a medication or drug substance."

The Limitations of Use, also verbatim: "Not indicated for treatment of HSDD in postmenopausal women or in men." And: "Not indicated to enhance sexual performance."

That second line is worth sitting with. Performance enhancement is the reason most grey-market buyers seek this compound out, and FDA looked at the same data and wrote into the label that the drug is not for that.

Dosing and hard limits: one 1.75 mg subcutaneous injection to the abdomen or thigh, at least 45 minutes before anticipated sexual activity. No more than one dose in 24 hours. "More than 8 doses per month is not recommended." There is no annual cap in the label — that figure, which circulates online, is not in the document. For converting a vial concentration into an injection volume, use the peptide dosing calculator alongside the reconstitution calculator, and note that the approved product is a fixed-dose autoinjector rather than a reconstituted vial.

Contraindication: uncontrolled hypertension or known cardiovascular disease. The label also states VYLEESI "is not recommended for patients at high risk for cardiovascular disease."

How close is PT-141 to melanotan II?

About one dalton. PT-141 and melanotan II share an identical cyclic backbone, the same lactam bridge, the same D-phenylalanine and the same norleucine; the only difference is the C-terminus, a free acid (–OH) on bremelanotide against a lysine amide (–NH₂) on melanotan II. That is 1,025.2 against 1,024.18 on the molecular weight scale — a separation of under 0.1% between an FDA-approved drug and a substance approved nowhere in the world.

PT-141 is a cyclic heptapeptide built from the α-MSH "message" core — the His-Phe-Arg-Trp pharmacophore — with a norleucine at position 4, a D-phenylalanine at position 7, and a side-chain-to-side-chain lactam bridge from Asp5 to Lys10 that closes the ring.

The relationship to melanotan II is the single most important identity fact about this compound, and it is almost always described wrongly. The two are not different peptides that happen to be related. They share an identical backbone, an identical lactam bridge, the same D-Phe, the same Nle. The only difference is the C-terminal group.

A mass difference of about 1.0 Da on a 1,025 Da molecule is a serious analytical problem for a buyer, and the consequences run through the rest of this article: purity testing cannot see it, and the legal gap between the two molecules is total.

How often do PT-141's side effects occur?

Frequently. Across 627 patients on VYLEESI in the phase 3 programme, nausea affected 40.0% against 1.3% on placebo, flushing 20.3%, headache 11.3% and vomiting 4.8%. Thirteen per cent needed anti-emetic therapy and 8% left the trial because of nausea alone. Overall, 18% of patients discontinued for adverse events, against 2% of the 620 on placebo. No boxed warning appears on the label.

The label notes that nausea "improves for most patients with the second dose," which is fair, and also means the first dose is where most people find out.

Blood pressure, from the label: maximal increases of 6 mmHg systolic and 3 mmHg diastolic, peaking 2–4 hours post-dose, with heart rate falling up to 5 beats per minute, returning to baseline usually within 12 hours. Those are modest numbers in a screened trial population from which cardiovascular disease was excluded — which is exactly the population grey-market buyers are not screened into.

Will PT-141 darken your skin?

At the label's frequency limit, rarely; above it, often. FDA's label reports focal hyperpigmentation — face, gingiva and breasts — in 1% of patients receiving up to eight doses per month. In a separate clinical study, 38% of patients developed it after taking VYLEESI daily for eight days. Patients with dark skin were more likely to develop it, and resolution after discontinuation was not confirmed in all patients.

The label's wording is specific: "focal hyperpigmentation, including involvement of the face, gingiva, and breasts, was reported in 1% of patients who received up to 8 doses per month." Then: "In another clinical study, 38% of patients developed focal hyperpigmentation after receiving VYLEESI daily for 8 days." And: "Patients with dark skin were more likely to develop focal hyperpigmentation. Resolution of the focal hyperpigmentation was not confirmed in all patients after discontinuation."

That 1%-versus-38% contrast is the most practically important number in this article, because it is the one the reader controls. The dosing limit is what keeps hyperpigmentation rare. Eight doses a month gives 1%. Daily dosing for eight days gives 38%, and it did not always reverse. Anyone dosing PT-141 outside the label's frequency limit is running the second experiment, not the first.

Why is bremelanotide legal in sport when melanotan II is not?

Because bremelanotide holds a current governmental approval and melanotan II does not. PT-141 is not named on the WADA 2026 Prohibited List, and the S0 catch-all — which captures substances with "no current approval by any governmental regulatory health authority" — does not obviously reach an FDA-approved drug. Melanotan II, approved nowhere, is caught by S0 and prohibited at all times. One terminal group separates the two.

The asymmetry runs further than anti-doping. Same backbone, one terminal group apart: one is a prescription medicine dispensed as an autoinjector; the other is the subject of enforcement actions in Ireland, Australia, the UK and the US.

For PT-141 specifically, the approval also means bremelanotide is a component of an FDA-approved drug — one of the three statutory routes under 21 U.S.C. § 353a(b)(1)(A) for 503A compounding. It does not appear on FDA's list of bulk substances that may present significant safety risks. None of that legitimises a research vial: selling an approved drug's active ingredient for human use without an application is the sale of an unapproved new drug, and "research use only" labelling is not a defence. See compounding pharmacy versus research peptide and our FDA peptide regulation timeline.

Which PT-141 claims survive the evidence?

Only one of nine. Of the nine claims made for PT-141 in this market, exactly one returns a clean True — that it is FDA-approved. A second, that it increases sexual desire, is true only in the statistical sense: about 0.3 questionnaire points. The rest fail outright, including approval for men, approval for performance enhancement, an increase in satisfying sexual events, and distinguishability from melanotan II by purity testing.

What do 242 lab tests and 65 shops show for PT-141?

The Purity Index records PT-141 at 99.70% across 242 independent HPLC tests from laboratories including Freedom Diagnostics, ILS, Kovera, Accurate Test Lab, MZ Biolabs and Ethos Analytics, across 225 verified shops (verified August 2026). Quantity variance runs −3.3% to +16.3%, with two vendors returning +16.3% overages. Price data shows 65 shops in stock at a median of $4.40 per milligram (verified 10 August 2026).

Testing runs current to late July 2026. The two +16.3% overages were a 30 mg label tested at 34.9 mg, and a 10 mg label tested at 11.63 mg. Endotoxin results are mostly absent.

PT-141 price data shows the lowest listing at $2.00/mg on a 10 mg vial and the highest at $9.59/mg on a 5 mg vial (verified 10 August 2026), across 68 of 77 live listings from 158 known shops. Vials run 5–10 mg at $20.00–$90.00. Those figures exclude shipping, taxes and customs, coupon codes, bulk tiers, multi-vial kits and account-gated pricing.

Those numbers sit inside a platform total of 11,852 independent lab tests across 118 peptides and 530 shops, with 1,283 community reviews (verified August 2026). None of that testing volume answers the question a PT-141 buyer most needs answered, which is the subject of the next section.

How do you verify PT-141 before you buy it?

No routine test can confirm it. A 99.70% HPLC result on a PT-141 sample would read identically if the vial contained melanotan II, because the two peptides differ by about one dalton and co-elute; HPLC measures homogeneity, not identity. Confirming bremelanotide at 1,025.2 rather than melanotan II at 1,024.18 requires high-resolution mass spectrometry or MS/MS fragmentation on the batch. A pure sample of the wrong molecule scores beautifully.

The purity figure is the least useful number on this compound, and it is worth being direct about why. Purity measures how much of the sample is one thing. It says nothing about which thing.

See mass spectrometry for peptides for what resolution actually buys you, and how to read peptide lab results for reading a certificate line by line. Compare vendors on the PT-141 compound page and see where to buy PT-141. For the nasal route some vendors promote, the intranasal peptide guide covers technique — but note that the approved product is a subcutaneous autoinjector, and no intranasal bremelanotide has ever been approved.

How does PT-141 compare with other melanocortin agonists?

PT-141 is not the only melanocortin agonist FDA approved in 2019, and the other one shows what regulatory caution looks like. Afamelanotide (Scenesse), approved the same year for erythropoietic protoporphyria, is a physician-inserted subcutaneous implant given every two months, administered only by someone trained by the manufacturer, with twice-yearly full-body skin examinations and an eight-year FDA-mandated skin-cancer registry attached. None of that surveillance exists in the grey market.

Afamelanotide is the useful third data point. It is a melanocortin agonist too, approved the same year, and its label attaches a surveillance apparatus that a regulator thought proportionate to the class. That is FDA's own read on how much monitoring a melanocortin agonist warrants. The fourth row makes a different point: an approval, on its own, does not transfer to a new use. Oxytocin is approved and its social-behaviour claims still failed replication. Approval status and evidence for a specific claim are separate questions, and PT-141 is the clearest example of the gap between them in the libido and sexual wellness cluster, alongside kisspeptin.

The trial that would settle this

The trial that would settle PT-141 has to enrol men, because the label expressly excludes them and no approval-grade evidence exists for the population the grey market actually serves. It would pre-specify satisfying sexual events as the primary endpoint rather than a questionnaire domain, run beyond 24 weeks, compare on-demand against frequent dosing to resolve the 1%-versus-38% hyperpigmentation question, and monitor cardiovascular outcomes in an unscreened population.

Frequently Asked Questions

Is PT-141 FDA-approved?

Yes. Bremelanotide was approved as VYLEESI on 21 June 2019 under NDA 210557 and is currently marketed by Cosette Pharmaceuticals. It is approved specifically for acquired, generalised hypoactive sexual desire disorder in premenopausal women.

Is PT-141 approved for men?

No. The label's Limitations of Use state it is "not indicated for treatment of HSDD in postmenopausal women or in men," and separately that it is "not indicated to enhance sexual performance." Those are FDA's words on the approved label, not an outside interpretation.

Did the trials show PT-141 improves people's sex lives?

The two co-primary endpoints were questionnaire scores measuring desire and distress, and both improved by about 0.3 points more than placebo, with p-values below 0.001. On satisfying sexual events — the endpoint counting actual encounters — FDA's label states there was "no significant difference between treatment groups."

How common are PT-141 side effects?

Nausea affected 40% of trial participants, needing anti-emetics in 13%. Flushing occurred in 20% and headache in 11%. Eighteen per cent of patients discontinued because of adverse events, versus 2% on placebo.

Will PT-141 make my skin darker?

At the label's limit of no more than eight doses per month, focal hyperpigmentation occurred in 1% of patients. In a separate study dosing daily for eight days, it occurred in 38%. Patients with darker skin were more likely to develop it, and resolution after stopping was not confirmed in all patients.

Can a lab test tell PT-141 from melanotan II?

Not with routine testing. The two differ only in the C-terminal group — an amide versus an acid — a mass difference of about 1 Da on 1,025 Da, under 0.1%. HPLC cannot separate them and nominal-mass MS is unreliable. High-resolution mass spectrometry or MS/MS fragmentation is required.

Where PT-141 sits

PT-141 is one of very few compounds in this market that genuinely cleared an FDA review, and reading what that review produced is more instructive than the approval itself. Two phase 3 trials in 1,267 women moved desire scores three-tenths of a point and left satisfying sexual events unchanged. FDA approved it anyway, and wrote every limit it thought necessary into the label.

That approval was reasonable on its own terms. Patient-reported outcomes are legitimate endpoints in a condition defined by distress, and a regulator that accepts them is not being lax. What the regulator then did was fence the product: premenopausal women only, not for men, not for performance, no more than eight doses a month, cardiovascular disease excluded, and a hyperpigmentation warning that jumps from 1% to 38% when the frequency limit is ignored.

The grey market sells it to men, for performance, without frequency limits, in vials that no routine test can distinguish from an unapproved substance one dalton away. Every one of those departures moves further from the conditions under which the drug was shown to be tolerable, in pursuit of an effect the trials did not demonstrate.

Browse the libido and sexual wellness peptides category, or our complete peptide guide with 118 compounds (verified August 2026). For per-injection volume, use the peptide dosing calculator alongside the reconstitution calculator. Compare shops through independent lab tests and community-verified shop reviews.

This article is for educational and informational purposes only and does not constitute medical advice. Peptides discussed may be investigational compounds not approved by the FDA (or equivalent regulators in your jurisdiction) for human use. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.