Overview
Sexual dysfunction is common, poorly treated by conventional approaches, and represents a genuine quality-of-life burden. PT-141 (bremelanotide) stands apart in this category as the only peptide with FDA approval for sexual dysfunction — specifically hypoactive sexual desire disorder (HSDD) in premenopausal women. The central (brain-based) mechanism distinguishes it from vasodilatory approaches like sildenafil.
PT-141 (Bremelanotide) — FDA-Approved
Mechanism: MC3R and MC4R agonism in the hypothalamus and limbic system. Unlike PDE5 inhibitors which work peripherally through vasodilation, PT-141 acts centrally to increase sexual desire and motivation. The bremelanotide mechanism targets the underlying desire pathway rather than the physical response.
Clinical evidence:
- RECONNECT trials: Two pivotal Phase 3 RCTs enrolling 1,247 premenopausal women with HSDD
- Primary endpoints: Increase in satisfying sexual events (SSE) and decrease in distress score
- Both trials met endpoints; FDA approved Vyleesi in June 2019
Male use: Not FDA-approved for men. Phase 2 data in males with erectile dysfunction showed improvement in erectile function with intranasal PT-141. Widely used off-label in men; higher risk tolerance and different evidence threshold in this use.
Administration: SC auto-injector, 45 minutes before sexual activity. Nausea is the primary side effect (40% rate in trials); flushing and hyperpigmentation with repeat use.
Oxytocin — Bonding and Arousal
Oxytocin (the “bonding hormone”) influences sexual arousal, pair bonding, orgasm, and trust. FDA-approved as Pitocin for obstetric use. Used off-label (intranasal, sublingual, sublingual troches from compounding pharmacies) for sexual and relational applications.
Evidence: Kosfeld 2005 (trust study), multiple studies on prosocial behavior. Sexual arousal enhancement evidence in humans is limited but mechanistically plausible. Intranasal bioavailability allows CNS targeting.
GH Axis and Libido
Growth hormone deficiency can contribute to reduced libido and sexual function in both sexes. GH secretagogues (Sermorelin, CJC-1295/Ipamorelin) that restore normal GH pulsatility may indirectly improve sexual function in GH-deficient individuals. This is a secondary effect, not a primary indication.
Evidence Summary
| Compound | Indication | Status | Evidence |
|---|---|---|---|
| PT-141 (Bremelanotide) | HSDD in women | FDA approved | Phase 3 RCT |
| PT-141 (off-label) | ED in men | Off-label | Phase 2 only |
| Oxytocin | Sexual function | Off-label | Limited |
| GH secretagogues | Libido (secondary) | Research | Indirect |
Related Peptides
PT-141 was derived from Melanotan II (MT-2), a tanning peptide that had sexual side effects as a notable adverse event in trials — which led to the discovery of the melanocortin-sexual desire pathway.