PT-141

PT-141 research peptide in Thailand

PT-141 (bremelanotide) is a synthetic cyclic heptapeptide analogue of α-MSH that acts as an agonist at the melanocortin receptors MC3R and MC4R, and it is one of the few research peptides with a completed phase 3 programme behind it — the FDA approved it as Vyleesi in 2019 for hypoactive sexual desire disorder in premenopausal women. Because it engages central melanocortin signalling rather than peripheral vasculature, neuroendocrine labs use it as a reference MC4R agonist.

Supplied as a lyophilised powder for laboratory research use only. This page summarises the published literature so a researcher can identify the compound; it is not a medicine, a sexual-health product, or a wellness product, and it gives no administration guidance.

Quick facts

Product

PT-141 (bremelanotide free base reference)

CAS number

189691-06-3

Molecular weight

~1025.2 Da

Regulatory status

Approved as Vyleesi (FDA, 2019); research-grade material here

Intended use

laboratory research use only

How PT-141 works

Bremelanotide is a cyclised, N-acetylated analogue of α-melanocyte-stimulating hormone. The cyclisation locks the His-D-Phe-Arg-Trp pharmacophore into a conformation that resists enzymatic degradation and biases binding toward MC3R and MC4R over the pigmentation-associated MC1R. MC4R is densely expressed in the hypothalamus, brainstem, and limbic system, where it also participates in energy homeostasis — which is why melanocortin agonism is studied across both neuroendocrine and metabolic models.

The pharmacologically interesting point for researchers is the site of action. PDE5 inhibitors act peripherally on vascular smooth muscle via cGMP; bremelanotide acts within the central nervous system, and preclinical work has mapped its effects onto hypothalamic melanocortin circuitry rather than genital haemodynamics (Pfaus et al., J Sex Med 2007). MC4R expression in cardiovascular control regions also explains the transient blood-pressure signal characterised in dedicated ambulatory monitoring trials.

Key research findings

• The two identical RECONNECT phase 3 trials randomised 1,267 premenopausal women to bremelanotide 1.75 mg subcutaneously as needed or placebo for 24 weeks, reporting statistically significant changes versus placebo on both coprimary endpoints — FSFI-desire domain (integrated +0.35, P<.001) and FSDS-DAO item 13 (integrated −0.33, P<.001) (Kingsberg et al., Obstet Gynecol 2019, PMID 31599840).
• In the 52-week open-label extension of those trials (684 enrolled, 272 completing), the most common drug-related treatment-emergent adverse events were nausea (40.4%), flushing (20.6%), and headache (12.0%), with nausea the only severe event affecting more than one participant in both studies (Simon et al., Obstet Gynecol 2019, PMID 31599847).
• A randomised ambulatory blood-pressure study in 397 women found the 1.75 mg dose produced small transient systolic increases of roughly 3.1–3.2 mmHg over the 0–4 hour post-dose interval, with peaks typically lasting under 15 minutes and accompanied by a heart-rate reduction of about 4.6 bpm (White et al., J Hypertens 2017, PMID 27977473).

Research applications

• Melanocortin receptor pharmacology, particularly MC3R versus MC4R selectivity and binding-affinity profiling.
• Central versus peripheral mechanism studies contrasting melanocortin agonism with PDE5-inhibitor pathways.
• Hypothalamic and limbic neuroendocrine signalling models, including dopaminergic and oxytocinergic circuit work.
• Cardiovascular safety pharmacology of MC4R agonists, following the ambulatory blood-pressure methodology.
• Structure-activity work on cyclic α-MSH analogues and peptide conformational stability.
• Receptor-agonist tolerability and adverse-event characterisation in preclinical models.

Dosing in the literature

Phase 2/3 trials studied the 0.75–1.75 mg span, and the approved label specifies 1.75 mg as needed. These figures report what published trials studied and what the approved label specifies; they are provided for literature reference only, not as administration guidance. To model concentrations and volumes for a study, use the peptide calculator.

Reconstitution & storage

Solvent

Bacteriostatic water — the common laboratory choice

Mixing

Add solvent down the vial wall and swirl gently until dissolved; do not shake

Storage

Refrigerate at 2–8 °C after reconstitution

Use within

About 28–30 days once reconstituted

Freeze / light

Keep lyophilised powder frozen or refrigerated; protect from direct light; avoid repeated freeze–thaw

These are standard laboratory handling conventions, not instructions for use. See bacteriostatic water for the standard diluent. In Thailand's heat and humidity, minimise time at ambient temperature and limit courier exposure to heat.

Selected research

• Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials — Obstetrics and Gynecology, 2019 (PMID 31599840).
• Long-Term Safety and Efficacy of Bremelanotide for Hypoactive Sexual Desire Disorder — Obstetrics and Gynecology, 2019 (PMID 31599847).
• Usefulness of ambulatory blood pressure monitoring to assess the melanocortin receptor agonist bremelanotide — Journal of Hypertension, 2017 (PMID 27977473).
• Melanocortin receptor agonists in the treatment of male and female sexual dysfunctions: results from basic research and clinical studies — Expert Opinion on Investigational Drugs, 2014 (PMID 25096243).
• Further indexed literature via PubMed search for bremelanotide.

Related compounds

• Oxytocin — a nine-amino-acid hypothalamic neuropeptide; oxytocinergic neurons in the paraventricular nucleus are downstream of melanocortin signalling, making it a frequent companion in central neuroendocrine circuit studies.
• Selank — a short regulatory neuropeptide used as a comparison point in CNS-active peptide research with a different receptor mechanism entirely.
• Bacteriostatic water — the standard diluent used to reconstitute lyophilised research peptides.

See also: more neuroendocrine signalling compounds.

PT-141 FAQ

Compliance note

PT-141 is provided for laboratory research use only. It is not intended for human or veterinary use, and it is not intended to diagnose, treat, cure, or prevent any disease. Trial results described on this page are findings of the specific cited studies, not claims about this product.