PT-141 and the melanocortin receptors: what the bremelanotide record states

PT-141 is the compound in this catalogue where an approved medicine and a research chemical sit closest together, which makes the difference between them easy to blur and important to state exactly. This page is about the melanocortin-receptor literature and the regulatory record. It makes no claim about what the compound does for anyone, contains no amount, no route and no schedule, and offers no anecdote.

What the molecule is

PT-141 is bremelanotide: a cyclic heptapeptide agonist at melanocortin receptors, and a metabolite of Melanotan II — itself a synthetic analogue of alpha-melanocyte-stimulating hormone developed in the pigmentation context. That lineage explains why the compound is filed under aesthetics in some catalogues and reproductive endocrinology in others.

There are five melanocortin receptors: MC1R, the pigmentation receptor on melanocytes; MC2R, the adrenocorticotropic hormone receptor; and MC3R, MC4R and MC5R, distributed differently again, with MC4R expressed in the central nervous system and long studied in energy balance. Bremelanotide is characterised as an agonist with activity at MC3R and MC4R.

The preclinical literature is about the central nervous system

This is the distinction the papers draw and the one most summaries lose. The melanocortin work concerns receptors in the brain, not blood vessels in the periphery — which is the explicit contrast with PDE5 inhibitors, whose literature is vascular.

Van der Ploeg and colleagues examined MC4R in sexual function in rodents in 2002 (PMID 12172010). Molinoff and colleagues set out the compound and its development rationale in 2003 (PMID 12851303). Pfaus and colleagues examined solicitation behaviour in the female rat under a melanocortin receptor agonist (PMID 15226502). Those are animal behavioural and receptor studies, and that is the whole of what they establish.

The clinical record, in the order it happened

The intranasal programme came first, and it was abandoned. Diamond and colleagues published a double-blind, placebo-controlled evaluation of intranasal PT-141 in healthy males and in men with mild-to-moderate erectile dysfunction in 2004 (PMID 14963471). Development in that formulation did not continue: increases in blood pressure were reported in the trial programme, and the sponsor stopped it in 2007. That failure is part of this compound's record and belongs beside the successful programme, not after it.

The second programme changed indication and population. Clayton and colleagues ran a randomised, placebo-controlled dose-finding trial of bremelanotide in premenopausal women with female sexual dysfunction, published in 2016 (PMID 27181790). The two phase 3 trials that followed, known together as RECONNECT, enrolled premenopausal women with hypoactive sexual desire disorder and were published in Obstetrics & Gynecology in 2019 (PMID 31599840). Prespecified and integrated subgroup analyses were published later (PMID 35230162).

What the endpoints were. Changes in scores on validated desire and distress instruments — questionnaire scales, completed by participants. The differences from placebo reported in those papers are modest, and anyone drawing a conclusion should read the trial publications and the agency review rather than a summary of either, including this one.

What the trials reported about tolerability. Nausea is reported among the most frequent adverse events in the published trials, alongside flushing and headache. The melanocortin system's pigmentation arm shows up too: focal hyperpigmentation is described in the record. These are reported observations in trial populations, not predictions about anybody.

What is approved, and where

The Canadian line is the one most often stated loosely. Health Canada's Drug Product Database is the public, authoritative record of what is authorised for sale in Canada, and anyone needing certainty should search it directly rather than take a storefront's word for it. Nothing on this site is an approved drug.

And the approved medicine is not the powder. Vyleesi is a specified formulation with a reviewed label: an indication, a population, contraindications, blood-pressure warnings and a prescriber. Lyophilised research material has none of that attached to it. The two share a molecule and nothing else — not the manufacturing standard, not the label, not the oversight, and not the evidence, which was generated for the medicine as approved.

For the same problem stated in a different catalogue entry — an approved drug whose research-chemical counterpart is routinely confused with it — see the tesamorelin buying guide. For another compound acting on central reproductive signalling, with a human physiology literature and no approval anywhere, see Kisspeptin-10. For the melanocortin system's other arm, pigmentation and the skin, see GHK-Cu and photoaging. Nothing here is medical, dosing, or therapeutic guidance.

Where the evidence stops

The approval is narrow. One indication, one population, one jurisdiction, one formulation. It is not a general finding about the molecule and it transfers nowhere.

The male literature stopped short. Early-phase work in men was published; the programme carrying it did not reach approval, which is evidence about development rather than about effect.

The blood-pressure signal is in the record. It ended one formulation's development and it is reflected in the approved product's label. It is the first thing to read, not a footnote.

Research material is unregulated by design. No indication, no label, no supervision. That is what "for laboratory use only" means, and on this compound it is the whole of the distinction.

PT-141 is supplied here as PT-141. Janoshik-verified by HPLC with mass-spec identity confirmation; 100% synthetic. The measured purity for each lot is stated on its product page. For laboratory research use only.

Common questions

Is PT-141 the same thing as Vyleesi? The same molecule, not the same product. Vyleesi is an FDA-approved formulation with a reviewed label, an indication and a population. Research material has a molecule and a certificate of analysis. The difference is everything the approval consists of.

Does it work? That question cannot be answered here, and a storefront answering it would be making a claim about goods. What exists is a trial record for a licensed medicine in premenopausal women with one diagnosis, with questionnaire endpoints and modest reported differences from placebo. It says nothing about anyone outside that population, and nothing about this material.

Is it approved in Canada? No. Bremelanotide has no Canadian marketing authorisation, and nothing sold here is an approved drug. Health Canada's Drug Product Database is where to confirm that for yourself.

Is it the same as Melanotan II? No. PT-141 is a metabolite of it, and a different molecule with a different receptor profile — which is why its literature is about central melanocortin signalling rather than pigmentation. Data on one is not data on the other.

Selected Research References

1. Van der Ploeg LH, Martin WJ, Howard AD, et al. A Role for the Melanocortin 4 Receptor in Sexual Function. Proceedings of the National Academy of Sciences. 2002;99(17):11381-11386. pubmed.ncbi.nlm.nih.gov/12172010
2. Molinoff PB, Shadiack AM, Earle D, Diamond LE, Quon CY. PT-141: A Melanocortin Agonist for the Treatment of Sexual Dysfunction. Annals of the New York Academy of Sciences. 2003;994:96-102. pubmed.ncbi.nlm.nih.gov/12851303
3. Diamond LE, Earle DC, Rosen RC, Willett MS, Molinoff PB. Double-Blind, Placebo-Controlled Evaluation of the Safety, Pharmacokinetic Properties and Pharmacodynamic Effects of Intranasal PT-141, a Melanocortin Receptor Agonist, in Healthy Males and Patients with Mild-to-Moderate Erectile Dysfunction. International Journal of Impotence Research. 2004;16(1):51-59. pubmed.ncbi.nlm.nih.gov/14963471
4. Pfaus JG, Shadiack A, Van Soest T, Tse M, Molinoff P. Selective Facilitation of Sexual Solicitation in the Female Rat by a Melanocortin Receptor Agonist. Proceedings of the National Academy of Sciences. 2004;101(27):10201-10204. pubmed.ncbi.nlm.nih.gov/15226502
5. Clayton AH, Althof SE, Kingsberg S, et al. Bremelanotide for Female Sexual Dysfunctions in Premenopausal Women: A Randomized, Placebo-Controlled Dose-Finding Trial. Women's Health (London). 2016;12(3):325-337. pubmed.ncbi.nlm.nih.gov/27181790
6. Kingsberg SA, Clayton AH, Portman D, et al. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials. Obstetrics & Gynecology. 2019;134(5):899-908. pubmed.ncbi.nlm.nih.gov/31599840
7. Simon JA, Kingsberg SA, Portman D, et al. Prespecified and Integrated Subgroup Analyses from the RECONNECT Phase 3 Studies of Bremelanotide. Journal of Women's Health. 2022;31(3):391-400. pubmed.ncbi.nlm.nih.gov/35230162

All products sold by NovaEvum are for research and laboratory use only. They are not intended for human or animal consumption, diagnosis, treatment, cure, or prevention of any disease.