A 7-amino-acid cyclic melanocortin peptide and the first FDA-approved treatment for hypoactive sexual desire disorder (HSDD) in premenopausal women. Acts centrally in the brain on MC4 receptors rather than peripherally like PDE5 inhibitors (Viagra).
PT-141 (Bremelanotide) is a cyclic 7-amino-acid peptide that activates melanocortin-4 receptors (MC4R) in the brain. Marketed as Vyleesi, it is the first and only FDA-approved treatment for hypoactive sexual desire disorder (HSDD) in premenopausal women.
PT-141 was originally developed from the tanning peptide melanotan II (which activates multiple melanocortin receptors). During clinical trials for melanotan II, researchers noticed an unexpected side effect — increased sexual arousal. This led to the development of PT-141 as a more selective MC4R agonist targeting sexual desire specifically.
PT-141 binds to the melanocortin-4 receptor (MC4R), a Gs-coupled GPCR expressed in the hypothalamus (paraventricular nucleus), amygdala, and other limbic structures involved in sexual behavior. MC4R activation increases dopaminergic signaling in the mesolimbic reward pathway, modulating the neural circuits that generate sexual desire. This central mechanism is why PT-141 works regardless of the physical cause of low desire — it targets the brain's desire circuits directly.
| Pathway | Effect | Significance |
|---|---|---|
| MC4R activation | Agonist binding in hypothalamic nuclei | Stimulates neural pathways underlying sexual desire and arousal |
| Dopamine modulation | Enhances dopaminergic signaling in reward circuits | Increases motivation and desire components of sexual behavior |
| Oxytocin release | MC4R activation promotes oxytocin release | May contribute to bonding and arousal aspects |
| Melanocortin effects | Some residual MC1R activity | Can cause transient skin darkening and facial flushing |
| Study | Design | Findings | Level |
|---|---|---|---|
| RECONNECT (Phase III) | RCT, n=1,247 premenopausal women with HSDD | Statistically significant increase in desire and decrease in distress vs placebo over 24 weeks | Level I |
| Male ED | Phase II trials | Some efficacy in erectile dysfunction, but development focused on female HSDD | Level II |
| Duration of effect | Clinical data | Single SC injection provides effect for ~24 hours; not a daily medication | Level I-II |
Nausea: Most common side effect (~40%). Usually mild and transient. Worse with first dose.
Flushing/skin darkening: Transient facial flushing. Some skin darkening possible due to residual MC1R activity.
Blood pressure: Transient increase in blood pressure after injection. Contraindicated in uncontrolled hypertension.
Dosing limit: FDA label limits use to no more than once every 24 hours and no more than 8 doses per month.
| Jurisdiction | Status |
|---|---|
| FDA | Approved: Vyleesi (bremelanotide) for HSDD in premenopausal women (2019). SC autoinjector. |
| EMA | Not approved in EU |
| WADA | Not specifically banned |