Peptides MEX / Comparisons
PT-141 vs Melanotan II: structure and clinical studies
PT-141, also called bremelanotide, and Melanotan II are cyclic peptides associated with the melanocortin system. Their carboxyl termini and the aims of the cited studies differ: structural similarity does not make pigmentation, sexual response and sexual desire equivalent outcomes.
Updated · Sources and editorial standards
| Feature | PT-141 / Bremelanotide | Melanotan II |
|---|---|---|
| Carboxyl terminus[1][2] | Free acid in bremelanotide | Amide in the published structure |
| Featured research[3][2] | Phase 3 RECONNECT trials | 1996 phase 1 pilot |
| Endpoint and population[3][2] | Desire and distress in women with HSDD | Pigmentation and physiological responses in three men |
The peptide terminus also differs
The bremelanotide label describes a cyclic heptapeptide with a free acid at the carboxyl terminus. The original Melanotan II publication describes a cyclic analogue with an amidated terminus. This chemical change distinguishes the entities, but does not itself rank clinical potency or safety.
Exploratory pigmentation and defined sexual-desire outcomes
The Melanotan II pilot included three men and recorded pigmentation and other physiological responses. The bremelanotide RECONNECT trials studied premenopausal women with hypoactive sexual desire disorder and assessed desire and associated distress. They do not share a population, measurement scale or clinical question, so their results are not a direct comparison.
Shared receptors, outcomes that need separation
According to its label, bremelanotide activates several melanocortin receptor subtypes; the precise mechanism behind its effect on the desire disorder remains undefined there. The label also recognizes pigmentation among possible effects. Reducing PT-141 to desire only and Melanotan II to pigmentation only therefore misses the biological overlap.
Questions about this reference
Are PT-141 and Melanotan II names for the same molecule?
No. The described structures differ at the carboxyl terminus: a free acid in bremelanotide and an amide in Melanotan II. Molecular relatedness does not remove that difference.
Sources and original reading
- VYLEESI — bremelanotide prescribing information
- Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study
- Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials
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