Hormonal Regulation FDA Approved

PT-141

Also known as: Bremelanotide

Molecular Identifiers

Molecular Formula

C50H68N14O10

CAS Number

189691-06-3

PubChem CID

9941379

UNII

6Y24O4F92S

Molecular Weight

1025.2 Da

Overview

Melanocortin MC4R receptor agonist. Research in sexual function. Effects last 6-12 hours. On-demand use.

FDA-approved in 2019 as Vyleesi® (bremelanotide) for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women. MC4R agonist with a central mechanism of action, independent of the vascular system.

Clinical interest in PT-141 (bremelanotide) centers on improvement of sexual desire and response through a central mechanism — distinct from PDE5 inhibitors like sildenafil, which act on the vascular system. Selective MC4R activation in the central nervous system engages dopaminergic pathways involved in desire, with effects lasting 6-12 hours after a single subcutaneous administration.

It was FDA-approved in 2019 as Vyleesi for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women, in an autoinjector. Outside that specific indication, it is prescribed off-label through compounding pharmacies for sexual dysfunction in men and women, in on-demand protocols limited to 2-3 administrations per week due to the risk of transient blood pressure increase and skin hyperpigmentation with repeated use.

It originated from research on melanotan-II analogs, during which a pro-sexual effect was incidentally observed in volunteers — which led to the targeted development of an MC4R agonist with a more favorable systemic profile.

Within the melanocortin family, PT-141 isolates the MC3R/MC4R axis for sexual function: unlike Melanotan I (MC1R, pigmentation) and Melanotan II (pan-agonist, from which it was derived), pigmentation effects are limited under on-demand use; compared with setmelanotide (MC4R-selective, daily chronic use for monogenic obesity), it operates in an on-demand regimen; and against endogenous α-MSH, it offers clinically useful half-life and an approved indication (Vyleesi).

Extended notation: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH

Cyclic peptide with non-natural amino acids

Half-life

~2-3 hours

Administration Route

Subcutaneous

Mechanism of Action

Selective MC4R receptor agonism in the CNS
Activation of central dopaminergic pathways
Vascular system-independent effect (unlike PDE5 inhibitors)

Dosage Protocol

Data compiled from the literature. This does not constitute medical advice.

Parameter	Value
Dose	500-2000 mcg per injection
Frequency	As needed, maximum 2-3x/week
Timing	1-2 hours before desired effect
Duration	On-demand use

Reported Side Effects

Adverse effects described in the literature. Severity and frequency vary between individuals.

Nausea
Facial flushing
Headache
Transient blood pressure increase

Product Properties

Purity	>99%
Appearance	White lyophilized powder
Solubility	Soluble in water and bacteriostatic water
Source	Solid-phase peptide synthesis (SPPS). Contains lactam bridge (cyclic structure).
Storage	Lyophilized: -20°C for up to 2 years, 2-8°C for up to 6 months. Reconstituted: 2-8°C for up to 4 weeks. Protect from light and moisture. Avoid repeated freeze-thaw cycles.