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Comparison

Melanotan I vs PT-141

Both are melanocortins, so the meaningful differences are in kinetics, evidence and regulatory status.

Melanotan I PT-141
Class Melanocortins Melanocortins
Evidence Regulator approved Regulator approved
Human trials ~12 ~20
Half-life ~1 hour (implant gives sustained release) ~2.7 hours
Reported range 500 mcg - 1 mg 1-2 mg
Frequency Daily, or 16 mg implant every 2 months (approved use) As needed, at most once per 24 hours and 8 doses per month
Routes Subcutaneous Subcutaneous, Intranasal
FDA approved Yes Yes
Research use only No No
Banned in sport No No
Studied for Erythropoietic protoporphyria, Photoprotection, Tanning Hypoactive sexual desire disorder in premenopausal women, Erectile dysfunction research
Reported side effects Nausea, Headache, Implant-site reactions, Darkening of existing naevi, Fatigue Nausea, Flushing, Injection-site reactions, Headache, Transient blood pressure increase

Melanotan I

Afamelanotide is a linear alpha-MSH analog with substitutions at positions 4 and 7 that increase potency and stability, and it is comparatively selective for the melanocortin-1 receptor. Selectivity means it stimulates eumelanin production without the MC4R-driven nausea and erectile effects of melanotan II. It is approved as a subcutaneous implant to increase pain-free light exposure in erythropoietic protoporphyria.

PT-141

Bremelanotide is a metabolite of melanotan II in which the C-terminal amide is replaced by a hydroxyl group, shifting selectivity toward melanocortin-4 receptors and away from MC1R. It acts on hypothalamic pathways governing sexual desire and arousal, a mechanism fundamentally different from PDE5 inhibitors, which act on penile vasculature. That distinction means it can work where sildenafil does not, and also that it does not require a vascular response to be effective.

Melanotan I vs PT-141: common questions

What is the difference between Melanotan I and PT-141?

Both are melanocortins. Melanotan I: A selective MC1R agonist, FDA approved as an implant for a rare photosensitivity disorder. PT-141: A melanocortin-4 selective agonist approved for hypoactive sexual desire disorder, acting centrally rather than vascularly.

Which has stronger evidence, Melanotan I or PT-141?

They sit at the same evidence level: regulator approved. Melanotan I has about 12 human studies and PT-141 about 20.

Are Melanotan I and PT-141 FDA approved?

Both are FDA approved. Melanotan I: Increase of pain-free light exposure in adults with erythropoietic protoporphyria (Scenesse). PT-141: Acquired, generalised hypoactive sexual desire disorder in premenopausal women (Vyleesi).

References

Regulatory and primary sources

  1. PubChem compound record (CID 16197727) ↗ · structure, identifiers, synonyms
  2. DailyMed: FDA-approved labeling for Melanotan I ↗ · indications, dosing, warnings as approved
  3. FDA Drugs@FDA database ↗ · approval history
  4. CAS Registry Number 75921-69-6 ↗ · chemical identity
  5. PubChem compound record (CID 9941379) ↗ · structure, identifiers, synonyms
  6. DailyMed: FDA-approved labeling for PT-141 ↗ · indications, dosing, warnings as approved
  7. FDA Drugs@FDA database ↗ · approval history
  8. CAS Registry Number 189691-06-3 ↗ · chemical identity

Published literature

  1. Perez-Bootello J, Cova-Martin R, Naharro-Rodriguez J, et al.. Vitiligo: Pathogenesis and New and Emerging Treatments.Int J Mol Sci 2023.PubMed 38139134 · doi:10.3390/ijms242417306
  2. Bayerl C. [Undesirable pigmentation].Hautarzt 2015.PubMed 26315100 · doi:10.1007/s00105-015-3671-4
  3. Cong TX, Hao D, Wen X, et al.. From pathogenesis of acne vulgaris to anti-acne agents.Arch Dermatol Res 2019.PubMed 30859308 · doi:10.1007/s00403-019-01908-x
  4. Stölzel U, Kubisch I, Stauch T. [Porphyrias-what is verified?].Internist (Berl) 2018.PubMed 30328490 · doi:10.1007/s00108-018-0509-z
  5. Zubair R, Hamzavi IH. Phototherapy for Vitiligo.Dermatol Clin 2020.PubMed 31753192 · doi:10.1016/j.det.2019.08.005
  6. Sweeney P, Gimenez LE, Hernandez CC, et al.. Targeting the central melanocortin system for the treatment of metabolic disorders.Nat Rev Endocrinol 2023.PubMed 37365323 · doi:10.1038/s41574-023-00855-y
  7. Minder EI, Schneider-Yin X. Afamelanotide (CUV1647) in dermal phototoxicity of erythropoietic protoporphyria.Expert Rev Clin Pharmacol 2015.PubMed 25470471 · doi:10.1586/17512433.2014.956089
  8. Wu J, Cotliar R. Afamelanotide: An Orphan Drug with Potential for Broad Dermatologic Applications.J Drugs Dermatol 2021.PubMed 33683075 · doi:10.36849/JDD.5526
  9. Hedlund P. PT-141 Palatin.Curr Opin Investig Drugs 2004.PubMed 15134289
  10. Dhillon S, Keam SJ. Bremelanotide: First Approval.Drugs 2019.PubMed 31429064 · doi:10.1007/s40265-019-01187-w
  11. Pettigrew JA, Novick AM. Hypoactive Sexual Desire Disorder in Women: Physiology, Assessment, Diagnosis, and Treatment.J Midwifery Womens Health 2021.PubMed 34510696 · doi:10.1111/jmwh.13283
  12. Lee JH, Lee JE, Harsh V, et al.. Pharmacotherapy for Sexual Dysfunction in Women.Curr Psychiatry Rep 2022.PubMed 35102537 · doi:10.1007/s11920-022-01322-7
  13. Burton CS, Mishra K. Pharmacologic therapeutic options for sexual dysfunction.Curr Opin Obstet Gynecol 2022.PubMed 36036468 · doi:10.1097/GCO.0000000000000821
  14. Nappi RE, Tiranini L, Martini E, et al.. Medical Treatment of Female Sexual Dysfunction.Urol Clin North Am 2022.PubMed 35428435 · doi:10.1016/j.ucl.2022.02.001
  15. Mayer D, Lynch SE. Bremelanotide: New Drug Approved for Treating Hypoactive Sexual Desire Disorder.Ann Pharmacother 2020.PubMed 31893927 · doi:10.1177/1060028019899152

Literature retrieved from PubMed on October 16, 2026, favouring human studies and reviews. Numbered markers in the text show which paper supports which statement; uncited entries are background reading.

Read this first This page compares published reference data. It is not medical advice and not a recommendation to use either compound. Several compounds documented on this site are not approved for human use.