PT-141 and Melanotan II are often compared because both act on melanocortin receptors and both are discussed for effects on sexual arousal. PT-141, also called bremelanotide, is FDA-approved as Vyleesi for hypoactive sexual desire disorder (HSDD) in premenopausal women. Melanotan II is unregulated and not approved anywhere.
At a glance
| PT-141 (bremelanotide) | Melanotan II | |
|---|---|---|
| What it is | Melanocortin receptor agonist (bremelanotide), FDA-approved as Vyleesi for hypoactive sexual desire disorder in premenopausal women | Synthetic melanocortin receptor agonist that stimulates tanning and also affects libido and appetite; unregulated |
| How it's thought to work | Activates central melanocortin receptors, mainly MC4R, in the brain; a central pathway rather than a vascular one | Activates melanocortin receptors non-selectively: MC1R drives pigmentation, and MC4R affects sexual arousal and appetite |
| Regulatory status | FDA-approved as Vyleesi for HSDD in premenopausal women; other uses are off-label | Not approved anywhere; not FDA-approved |
| Strength of evidence | Human trials and FDA approval for one indication | Small, old human studies: a 1996 pilot in three volunteers and a 1998 crossover study in 10 men |
| Reported side effects | Nausea (most common), flushing, headache, transient blood pressure increase, possible skin darkening with repeated use | Nausea, flushing, spontaneous erections, appetite suppression, darkening of moles and new pigmented spots; melanoma case reports, causal link not established |
| Common vial sizes | 10mg | 10mg |
| Mixing math example | 10 mg + 2 mL BAC water = 5,000 mcg/mL, 50 mcg per unit | 10 mg + 2 mL BAC water = 5,000 mcg/mL, 50 mcg per unit |
Key differences
PT-141 is studied for activating central melanocortin receptors, mainly MC4R, in the brain. Melanotan II activates melanocortin receptors non-selectively: MC1R activity drives skin pigmentation, while MC4R activity affects sexual arousal and appetite.
PT-141 is FDA-approved as Vyleesi for HSDD in premenopausal women; other uses are off-label. Melanotan II is not FDA-approved and is not approved anywhere; a related compound, afamelanotide, is approved for a rare condition.
PT-141's most common reported side effect is nausea, along with flushing, headache, a transient increase in blood pressure and, with repeated use, possible skin darkening. Melanotan II's reported side effects include nausea, flushing, spontaneous erections, appetite suppression, and darkening of moles and new pigmented spots.
What the research covers
PT-141 has the human trials behind its FDA approval. Melanotan II's human data are small and old: a 1996 pilot study in three volunteers and a 1998 crossover study in 10 men. A 2017 review linked unregulated melanotan use to mole changes and noted case reports of melanoma, although a causal link has not been established.
Sources
- Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials. Kingsberg SA et al. Obstetrics and Gynecology, 2019. Human trial
- Melanocortin 4 receptor agonism enhances sexual brain processing in women with hypoactive sexual desire disorder. Thurston L et al. Journal of Clinical Investigation, 2022. Human trial
- VYLEESI (bremelanotide injection) - Highlights of Prescribing Information. U.S. Food and Drug Administration, 2019. Fda label
- Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Dorr RT et al. Life Sci, 1996. Human trial
- Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. Wessells H et al. J Urol, 1998. Human trial
- Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Habbema L et al. Int J Dermatol, 2017. Review
Frequently asked questions
What is the difference between PT-141 and Melanotan II?
PT-141 (bremelanotide) acts mainly on MC4R in the brain and is FDA-approved as Vyleesi for HSDD in premenopausal women. Melanotan II activates melanocortin receptors non-selectively, including MC1R, which drives pigmentation.
Is PT-141 or Melanotan II FDA-approved?
PT-141 is FDA-approved as Vyleesi for HSDD in premenopausal women. Melanotan II is not approved anywhere.
Does Melanotan II affect skin pigmentation?
Yes. Melanotan II activates MC1R, which drives pigmentation, and darkening of moles and new pigmented spots are reported side effects.
Are PT-141 and Melanotan II the same thing?
No. They are different melanocortin peptides with different receptor activity and different regulatory status.
Both entries, plus the calculator
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