Overview
PT-141 (bremelanotide) is a synthetic melanocortin peptide and the first — and currently only — FDA-approved treatment for hypoactive sexual desire disorder (HSDD) in premenopausal women. Marketed as Vyleesi by Palatin Technologies and AMAG Pharmaceuticals, it represents a novel pharmacological approach to female sexual dysfunction: rather than acting on the cardiovascular system (as sildenafil does), PT-141 acts centrally in the brain to modulate sexual desire through melanocortin receptor pathways.
The compound originated from research into the pigmentation effects of Melanotan II, during which researchers incidentally observed potent sexual arousal side effects. PT-141 was subsequently developed as a stripped-down derivative optimized for sexual function without Melanotan II’s tanning effects.
Mechanism of Action
Melanocortin Receptor Agonism: PT-141 binds to and activates melanocortin receptors MC3R and MC4R in the hypothalamus. MC4R in particular has been identified as a key regulator of sexual function — animal studies show that MC4R knockout mice have significantly impaired sexual behavior.
Central (Not Vascular) Mechanism: Unlike PDE5 inhibitors (Viagra, Cialis), which work peripherally by increasing blood flow to genital tissue, PT-141 acts centrally — modulating the neural circuitry of desire and arousal in the hypothalamus. This makes it the first centrally-acting sexual function agent.
Dopamine Pathway Interaction: MC4R activation in the paraventricular nucleus increases dopaminergic activity, which is thought to underlie the pro-sexual effect. This is mechanistically similar to Addyi (flibanserin), which acts on serotonin and dopamine receptors, but through an entirely different receptor class.
Clinical Research & Evidence
Evidence Level: 🟢 EL1 — Phase III RCTs, FDA approved (HSDD in premenopausal women)
| Trial | N | Duration | Key Finding |
|---|---|---|---|
| RECONNECT Study 1 | 394 | 24 weeks | Significantly more satisfying sexual events vs. placebo |
| RECONNECT Study 2 | 384 | 24 weeks | Significantly reduced distress related to low desire |
| Phase IIa (men) | ~20 | Single dose | 80% of men with erectile dysfunction achieved erections; 67% with psychogenic ED |
Note on male use: PT-141 is not FDA-approved for men, but Phase II data showed efficacy for psychogenic erectile dysfunction — a significant finding since PDE5 inhibitors are less effective for psychogenic (rather than organic/vascular) ED. Off-label use in men remains in research territory.
FDA-Approved Indication
- Vyleesi (1.75 mg/dose): Hypoactive sexual desire disorder (HSDD) in premenopausal women
- One dose subcutaneously in abdomen or thigh, at least 45 minutes before anticipated sexual activity
- Maximum: 1 dose per 24 hours; no more than 1 dose per 8 hours
- Not for use during pregnancy
Side Effects & Contraindications
Common:
- Nausea (40% in trials — most common side effect; self-limiting, typically resolves within 2 hours)
- Flushing (20%)
- Injection site reactions
- Transient hyperpigmentation (especially with higher or frequent doses)
- Headache
Serious:
- Transient hypertension: PT-141 can transiently increase blood pressure. Not recommended in high CV risk patients.
- Hyperpigmentation: With repeated use, can cause focal hyperpigmentation of face, breasts, genitals
Contraindications:
- High cardiovascular risk (uncontrolled hypertension, established CVD)
- Use of organic nitrates or nitric oxide donors
- Hypersensitivity
Legal & Regulatory Status
| Region | Status |
|---|---|
| United States | FDA approved (Vyleesi, June 2019) — for premenopausal women with HSDD |
| European Union | Not EMA approved |
| UK | Not MHRA approved |
| Off-label male use | Research only; not approved for men in any jurisdiction |
Compounding: As an FDA-approved active ingredient, PT-141 is sometimes compounded in alternate concentrations/formulations — check current FDA guidance on compounded bremelanotide.
Research Citations
- Clayton AH, et al. Bremelanotide for Female Sexual Dysfunctions in Premenopausal Women. Obstet Gynecol. 2016.
- Simon JA, et al. One-year interim results from the RECONNECT study. J Sex Med. 2019.
- Safarinejad MR. The role of the melanocortin system in male sexual dysfunction. J Androl. 2008.
- King SH, et al. Melanocortin receptors, melanotropic peptides and penile erection. Curr Top Med Chem. 2007.