PT-141 β Research Dossier
Evidence grading
Mechanism
MC4R/MC3R agonist
Central hypothalamic sexual-arousal pathway
FDA approval
June 2019
Premenopausal HSDD; Vyleesi; prescription-only
Phase 3 (RECONNECT)
~1,200+ women
Two pivotal RCTs, statistically significant outcomes
Approved in men?
No
Male use is off-label; not FDA-approved for any male indication
PT-141 (bremelanotide) is one of the very few research-community peptides that is also a fully FDA-approved drug β with two Phase 3 RCTs and a 2019 approval for hypoactive sexual desire disorder in premenopausal women, and clear limits on what the approval does and does not cover.
PT-141 (bremelanotide; brand Vyleesi) is a synthetic cyclic heptapeptide melanocortin-receptor agonist developed by Palatin Technologies by cyclising and modifying Melanotan II β itself an Ξ±-MSH analogue β to shift selectivity away from broad pigmentation and appetite activity toward central sexual-arousal pathways. It received FDA approval in June 2019 for acquired, generalised hypoactive sexual desire disorder (HSDD) in premenopausal women: the first approved melanocortin-receptor agonist and the first on-demand HSDD therapy.
Its plasma half-life is approximately 2.7 hours, but the subjective effect outlasts plasma presence, consistent with downstream neuromodulatory signalling. It acts via a central nervous-system mechanism β hypothalamic MC4R and MC3R in the paraventricular nucleus and medial preoptic area β which is fundamentally different from PDE5 inhibitors such as sildenafil, which act peripherally on genital blood flow.
βThe two pivotal RECONNECT trials found on-demand 1.75 mg subcutaneous bremelanotide produced statistically significant improvements versus placebo in the FSFI desire domain and FSDS distress score (P<0.001) in premenopausal women with HSDD.β
β Kingsberg SA et al., Obstet Gynecol 2019
Mechanism
PT-141 activates melanocortin receptors β principally MC4R, with MC3R activity β in the hypothalamus, modulating the dopaminergic sexual-arousal circuit in the paraventricular nucleus and medial preoptic area. This central mechanism distinguishes it from peripheral vasodilators: where PDE5 inhibitors increase genital blood flow, bremelanotide acts on the neural substrates of desire and arousal.
It was developed from Melanotan II (MT-II), a broad Ξ±-MSH analogue, by cyclisation and structural modification to improve receptor selectivity and reduce pigmentation and other off-target effects of the parent molecule.
Clinical evidence base
Phase 3 β RECONNECT trials
The two pivotal RECONNECT trials (Kingsberg et al., 2019) were randomised, double-blind, placebo-controlled studies enrolling over 1,200 premenopausal women with HSDD. On-demand subcutaneous bremelanotide 1.75 mg produced statistically significant improvements versus placebo in the Female Sexual Function Index (FSFI) desire domain and Female Sexual Distress Scale (FSDS) score (P<0.001). These results formed the basis for FDA approval in June 2019.
Off-label and male data
Earlier clinical work explored male sexual dysfunction, including use in PDE5-inhibitor non-responders. Bremelanotide is not FDA-approved for any indication in men. Male-use data is limited to earlier phase studies and rests on substantially weaker evidence than the approved indication.
Safety
The most common adverse events are nausea (approximately 40% on the first dose, diminishing with subsequent use), flushing, and headache, with transient blood-pressure elevation. Hyperpigmentation is the dose-limiting concern with heavy or repeated use β a direct echo of the melanocortin family pharmacology shared with Melanotan II. The approved 1.75 mg on-demand dose was selected in part to manage these effects.
Regulatory status
FDA-approved (US, June 2019, Vyleesi) for premenopausal HSDD; prescription-only. Not approved by the MHRA or EMA; in the UK it has no marketing authorisation and material supplied for laboratory work is research-use-only. The Melanotan II lineage is the context for UK regulatory sensitivities around this peptide family; PT-141 is a distinct, approved molecule, but sits in the same melanocortin class.
Evidence grade: Approved. Among the strongest evidence bases of any compound in this journal for its specific indication β two Phase 3 RCTs and an FDA approval. Claims beyond premenopausal HSDD (male use, performance use) are off-label and rest on weaker data.
References
- 1
Kingsberg SA, et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials (RECONNECT) Obstet Gynecol 2019.
- 2
US FDA Vyleesi (bremelanotide) prescribing information and approval documentation FDA Drug Approval Documentation 2019.
- 3
Wikberg JES, Mutulis F. Targeting melanocortin receptors: an approach to treat weight disorders and sexual dysfunction Nat Rev Drug Discov 2008.
- 4
Molinoff PB, et al. PT-141 (bremelanotide) early development β melanocortin agonism and sexual function Ann N Y Acad Sci 2003.
Research & Laboratory Use Only
This dossier is compiled for research planning and educational purposes only. It summarises published scientific literature and does not constitute medical advice, dosing guidance, or a therapeutic claim. All Nexyra Lab products are for research purposes only and are not for human or veterinary use. Nothing in this document should be interpreted as recommending, endorsing, or facilitating the self-administration of any compound.
A one-time legal review of this template and disclaimer is recommended before the Journal section is made publicly accessible, given the health-adjacent nature of this content.
