PT-141 (Bremelanotide)

It is the rare grey-market peptide that actually grew up and passed a real exam, but only a narrow one. It is genuinely licensed for one specific group of women, where it gives a modest, real benefit at the cost of frequent nausea. Everything sold for everyone else is coasting on that single passing grade without sitting its own test.

A cyclic peptide analogue of alpha-melanocyte-stimulating hormone that agonises central melanocortin receptors (notably MC4R and MC3R). This activates brain pathways governing sexual desire and arousal, acting centrally rather than on genital blood flow. It is given by subcutaneous injection on an as-needed basis. Off-target MC1R activity underlies flushing and skin pigmentation. Melanocortin signalling also drives the transient blood-pressure rise seen with the drug.

Research contexts. Not proven uses, and not recommendations.

Strong for its narrow approved use. Two identical Phase 3 randomised, double-blind, placebo-controlled trials (RECONNECT, integrated N approximately 1,247 premenopausal women with HSDD) showed statistically significant improvements in sexual desire and reductions in associated distress versus placebo, leading to FDA approval (Vyleesi, 2019). A 52-week open-label extension supported longer-term tolerability and durability. Effect sizes were modest, not transformative, and discontinuation was common, mainly due to nausea. Evidence for uses in men or for general libido enhancement is far thinner. The earlier intranasal erectile-dysfunction programme was discontinued partly over blood-pressure concerns, with no comparable Phase 3 efficacy package for those populations.

• !Nausea is very common (~40% of users) and the leading reason people stop. Flushing (~20%) and headache (~11-12%) are also frequent.
• !Transiently raises blood pressure and lowers heart rate. Caution is needed in people with uncontrolled hypertension or established cardiovascular disease.
• !Repeated use can cause focal skin hyperpigmentation (a melanocortin class effect), including on the face and gums.
• !Approved only for one specific population (premenopausal women with HSDD). Use in men or for general 'libido boosting' is extrapolation beyond the indication without equivalent trial support.
• !Not licensed by the MHRA in the UK or approved in the EU. Material sold online is unlicensed 'research chemical' of unverified identity, purity and sterility, with no pharmacy oversight.
• !Efficacy even in the approved group is modest, not transformative.

Not a licensed medicine in the UK. Bremelanotide has no MHRA marketing authorisation, and Vyleesi is a US (FDA) approval only with no EU approval. It is not available on prescription here. Product sold by UK suppliers is unlicensed material marketed as a "research chemical" or "not for human consumption", outside the Human Medicines Regulations 2012 framework for approved medicines. Supplying or advertising it for human use would breach UK medicines law.

• NCT02333071· Phase 3· Completed

  Study to Evaluate the Efficacy/Safety of Bremelanotide in Premenopausal Women With HSDD (RECONNECT, Study 301)

  One of the two pivotal identical RECONNECT trials supporting Vyleesi approval.

• NCT02338960· Phase 3· Completed

  Bremelanotide in Premenopausal Women With HSDD (RECONNECT, Study 302)

  Second identical pivotal RECONNECT trial.

1. 01
   Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials — Kingsberg SA, Clayton AH, Portman D, et al., Obstetrics & Gynecology (2019)

   Pivotal identical Phase 3 RECONNECT trials underpinning FDA approval; significant improvements in desire and distress vs placebo, with high nausea-driven discontinuation.

2. 02
   Long-Term Safety and Efficacy of Bremelanotide for Hypoactive Sexual Desire Disorder — Simon JA, Kingsberg SA, Portman D, et al., Obstetrics & Gynecology (2019)

   52-week open-label extension of RECONNECT describing longer-term tolerability and durability; nausea ~40%, flushing ~21%, headache ~12%.

3. 03
   Safety Profile of Bremelanotide Across the Clinical Development Program — Clayton AH, Kingsberg SA, Portman D, et al., Journal of Women's Health (2022)

   Pooled safety analysis across phases 1-3 (~3,500 subjects): nausea, flushing, headache, injection-site reactions, transient blood-pressure rise and hyperpigmentation.

4. 04
   VYLEESI (bremelanotide injection) US Prescribing Information / FDA approval, US FDA / accessdata.fda.gov (2019)

   Initial US approval June 2019 for acquired, generalised HSDD in premenopausal women; cardiovascular cautions and contraindications.