PT-141 vs Melanotan I

Both are melanocortin peptides derived from alpha-MSH. Melanotan-1 (afamelanotide) acts mainly at MC1R to darken skin and is approved for erythropoietic protoporphyria; PT-141 (bremelanotide) acts centrally at MC3R/MC4R and is approved for hypoactive sexual desire disorder.

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PT-141

A cyclic melanocortin-receptor agonist derived from melanotan II, approved in the US for hypoactive sexual desire disorder in premenopausal women.

BEST STUDIED FOR

Melanocortin

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Melanotan I

A linear α-MSH analogue that selectively activates MC1R, approved (as an implant) to prevent phototoxicity in erythropoietic protoporphyria.

BEST STUDIED FOR

Melanocortin

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SIDE BY SIDE

	PT-141	Melanotan I
The key difference	MC3R/MC4R agonist (sexual function)	MC1R-focused agonist (pigmentation)
Class	Melanocortin	Melanocortin
Mechanism	Bremelanotide activates melanocortin receptors (mainly MC4R, also MC1R) in the central nervous system.	Afamelanotide binds the melanocortin-1 receptor on melanocytes, increasing eumelanin production.
Status	FDA-approved (2019) for acquired, generalised HSDD in premenopausal women; earlier developed as a nasal spray for erectile dysfunction.	Approved in the EU (2014) and US (2019) as a subcutaneous implant for erythropoietic protoporphyria (EPP). Unregulated injectable "melanotan" products are a separate, unapproved market.
Reported safety signals	Approval-era data list nausea, flushing and transient blood-pressure increase; focal hyperpigmentation has been reported with repeated use.	In the EPP trials the implant was well tolerated; dermatology reviews warn about unregulated use of melanotan products and the need for mole surveillance.
A key study	Summarises the development and 2019 US approval of bremelanotide as a melanocortin receptor agonist for HSDD. (Drugs 2019, PMID 31429064)	Randomised trials measured pain-free sunlight exposure and safety with afamelanotide implants in EPP. (N Engl J Med 2015, PMID 26132941)

WHEN TO RESEARCH WHICH

Melanotan-1 for pigmentation and photoprotection research; PT-141 for central melanocortin signalling. Both are discussed here strictly as research compounds; nothing on this page is medical advice or a dosing guide.

REFERENCES (PUBMED)

[PT-141] Bremelanotide: First Approval — Drugs 2019. PMID 31429064
[PT-141] PT-141 Palatin — Curr Opin Investig Drugs 2004. PMID 15134289
[PT-141] Targeting the central melanocortin system for the treatment of metabolic disorders — Nat Rev Endocrinol 2023. PMID 37365323
[Melanotan I] Afamelanotide for Erythropoietic Protoporphyria — N Engl J Med 2015. PMID 26132941
[Melanotan I] Afamelanotide: A Review in Erythropoietic Protoporphyria — Am J Clin Dermatol 2016. PMID 26979527
[Melanotan I] Afamelanotide in protoporphyria and other skin diseases: a review — Postepy Dermatol Alergol 2024. PMID 38784937

FREQUENTLY ASKED

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

What is the regulatory status of PT-141 and Melanotan I?

PT-141: FDA-approved (2019) for acquired, generalised HSDD in premenopausal women; earlier developed as a nasal spray for erectile dysfunction. Melanotan I: Approved in the EU (2014) and US (2019) as a subcutaneous implant for erythropoietic protoporphyria (EPP). Unregulated injectable "melanotan" products are a separate, unapproved market.

What safety signals have been reported?

PT-141: Approval-era data list nausea, flushing and transient blood-pressure increase; focal hyperpigmentation has been reported with repeated use. Melanotan I: In the EPP trials the implant was well tolerated; dermatology reviews warn about unregulated use of melanotan products and the need for mole surveillance.

Which studies is this comparison based on?

For PT-141: “Bremelanotide: First Approval” (PMID 31429064); “PT-141 Palatin” (PMID 15134289); “Targeting the central melanocortin system for the treatment of metabolic disorders” (PMID 37365323). For Melanotan I: “Afamelanotide for Erythropoietic Protoporphyria” (PMID 26132941); “Afamelanotide: A Review in Erythropoietic Protoporphyria” (PMID 26979527); “Afamelanotide in protoporphyria and other skin diseases: a review” (PMID 38784937).