Background
Hypoactive sexual desire disorder (HSDD) — characterized by persistent low sexual desire causing personal distress — affects approximately 10% of premenopausal women and was largely undertreated pharmacologically prior to 2019. The RECONNECT program comprised two replicate Phase 3 randomized controlled trials (Study A and Study B) that evaluated subcutaneous bremelanotide 1.75 mg as an on-demand treatment for HSDD in premenopausal women.
These trials were pivotal for the FDA approval of bremelanotide (Vyleesi™) in June 2019 — the second FDA-approved pharmacologic treatment for HSDD after flibanserin (2015), and the first on-demand (non-daily) option.
Methods
Design: Two replicate multicenter, double-blind, placebo-controlled, parallel-group Phase 3 trials
Population: 751 premenopausal women (combined across both studies) with HSDD per DSM-5 criteria, diagnosed by standardized clinical interview, with documented personal distress
Intervention: Subcutaneous bremelanotide 1.75 mg self-administered on-demand (at least 45 minutes before anticipated sexual activity), up to once per 24 hours
Primary endpoints:
- Change from baseline in Female Sexual Function Index — Desire domain (FSFI-D)
- Change in Female Sexual Distress Scale — Desire, Arousal, Orgasm (FSDS-DAO) total score
Secondary endpoints:
- Number of sexually satisfying events (SSEs) per 28 days
- Patient Global Impression of Improvement (PGI-I)
Key Findings
Primary Efficacy (Combined Studies A + B):
| Endpoint | Bremelanotide | Placebo | p-value |
|---|---|---|---|
| FSFI-D change | +0.44 | +0.19 | < 0.001 |
| FSDS-DAO change | −11.0 | −6.8 | < 0.001 |
| SSEs/28 days | +0.7 | +0.4 | < 0.01 |
| PGI-I “improved” | 47% | 35% | < 0.01 |
Patient-Reported Distress:
- Significant reductions in personal distress about sexual function — the clinically most meaningful outcome for HSDD patients
- Effects were consistent across age subgroups (24–49 years), relationship status, and duration of HSDD symptoms
Tolerability Profile:
- Nausea: 40% bremelanotide vs. 1% placebo (most common AE; transient, majority resolved within 2 hours)
- Flushing: 20% vs. 2%
- Headache: 11% vs. 7%
- Blood pressure: Transient mean increase of ~6 mmHg systolic that resolved within 12 hours — not clinically significant in the study population
- Discontinuation due to AEs: 8% bremelanotide vs. 2% placebo
Regulatory Outcome:
- FDA approved bremelanotide (Vyleesi™) June 2019 for premenopausal women with acquired, generalized HSDD
- Labeled as on-demand (not daily), distinguishing it from flibanserin’s daily dosing requirement
Clinical Significance
- On-demand dosing advantage: Unlike flibanserin (daily pill with alcohol interaction restrictions), bremelanotide is used only when sexual activity is planned — reducing cumulative exposure and offering flexible use aligned with patient lifestyle
- Desire-specific mechanism: Bremelanotide’s central MC4R agonism directly targets the desire circuitry deficit underlying HSDD rather than treating downstream arousal
- Distress reduction: The FSDS-DAO improvement confirms that the drug addresses the distress criterion — not just statistical improvements on desire scales — validating clinical meaningfulness
- Nausea management: Prescribing information recommends pre-treatment with ondansetron (anti-emetic) to manage nausea in patients who experience it; newer formulation research ongoing
Limitations
- Modest absolute effect sizes (SSE increase of 0.7/month vs. 0.4 placebo) — the clinical meaningfulness per individual patient is modest
- 24-week trial; long-term efficacy data beyond 6 months are limited
- Nausea and tolerability burden may limit real-world uptake
- Blood pressure increase precludes use in women with uncontrolled hypertension or high cardiovascular risk
- Not studied in postmenopausal women or men in the RECONNECT program (though male ED trials are in development)