What is PT-141?
PT-141 (bremelanotide) is a cyclic analog of alpha-melanocyte-stimulating hormone (α-MSH). It was originally developed as a tanning agent (Melanotan I and II), but was found to have effects on sexual function in unexpected clinical studies.
It is the only FDA-approved treatment for hypoactive sexual desire disorder (HSDD) in premenopausal women, under the brand name Vyleesi (Palatin Technologies/AMAG Pharmaceuticals).
Why PT-141 is different
Previous treatments for female sexual dysfunction had limited efficacy because they acted peripherally. PT-141 acts directly in the central nervous system:
- Binds to melanocortin receptors MC3R and MC4R in the hypothalamus.
- Activates dopaminergic pathways related to motivation and desire.
- The result is not simply genital vasodilation, but central modulation of desire — the root of the problem in HSDD.
In men, it has also been investigated for erectile dysfunction, functioning even in cases where PDE5 inhibitors (sildenafil, tadalafil) are not effective — because its mechanism is completely different.
Clinical trials (Phase 3)
The RECONNECT studies (NEJM, 2019) in women with HSDD showed:
- Significant increase in sexual desire (FSDS-DAO scale) vs. placebo.
- Average response of +0.5 satisfying sexual events/month — modest but statistically significant.
- The benefit was more pronounced in women with greater subjective distress from low libido.
Adverse effects
- Nausea: 40% of patients (the most frequent adverse effect; generally mild and lasting 1–3 hours).
- Facial flushing/redness: 20%.
- Headache: 11%.
- Hyperpigmentation: With frequent repeated use (MC1R activation in melanocytes).
- Transient hypertension: Contraindicated in uncontrolled hypertension; monitor blood pressure.
Male research use
In men, Phase 2 studies reported:
- Spontaneous erections even without visual stimulation.
- Effective in psychogenic and organic erectile dysfunction.
- Did not enter Phase 3 for the male indication due to commercial decisions.
In women (Vyleesi), requires medical prescription. Research use must be under medical supervision. Contraindicated in uncontrolled hypertension and cardiovascular disease.
Reported protocol (research reference)
| Vial sizes | 10 mg |
|---|---|
| Reported dose | FDA-approved protocol (Vyleesi): 1.75 mg subcutaneous 45 minutes before sexual activity. Maximum 1 dose/24h and 1 dose/month for continued use. Investigational use reports higher ranges. |
| Half-life | Approximately 2.7 hours. |
| FDA status | FDA approved |