With oral naltrexone
Safety flag
Bremelanotide substantially decreases oral naltrexone exposure and can cause treatment failure.
Interaction evidence source All research profiles
Sexual health
PT-141
Prepared by the ezGLP team. Sources last checked . Profile reviewed .
Also known as Bremelanotide
Routes represented in the knowledgebase: Subcutaneous (SubQ).
Educational overview
PT-141 is listed in the ezGLP knowledgebase under Sexual health. Evidence and regulatory status can vary by formulation, route, and jurisdiction.
PT-141 is the development code for bremelanotide, a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone and a metabolite of Melanotan II in which the terminal amide is replaced by a carboxylic acid. It is classed as a melanocortin receptor agonist that activates several receptor subtypes, with MC1R and MC4R binding considered most relevant at therapeutic exposure. Its effect on sexual desire is thought to arise from MC4R signalling in the hypothalamus rather than from vascular action, distinguishing it from phosphodiesterase-5 inhibitors. Bremelanotide was originally studied as a nasal spray and then developed as a subcutaneous injection by Palatin Technologies and AMAG Pharmaceuticals.
Bremelanotide has the strongest evidence base among the melanocortin peptides described here because it completed a full regulatory programme. The RECONNECT programme comprised two identical twenty-four-week randomised, double-blind, placebo-controlled phase 3 trials in 1,247 premenopausal women with acquired, generalised hypoactive sexual desire disorder, published in 2019, followed by a fifty-two-week open-label extension. Both trials met their co-primary endpoints of improved desire and reduced distress, with modest effect sizes. Nausea was the most frequent adverse event and the leading reason for discontinuation. Earlier studies in men with erectile dysfunction did not proceed to approval, and the FDA label states that the mechanism in women is unknown.
Bremelanotide is FDA-approved as Vyleesi, a single-dose prefilled autoinjector for subcutaneous use, approved in June 2019 for premenopausal women with acquired, generalised hypoactive sexual desire disorder not attributable to a medical or psychiatric condition, relationship problems, or medication. The label states it is not indicated for postmenopausal women or men and not intended to enhance sexual performance, and carries warnings about transient blood pressure increases with heart-rate reduction, focal hyperpigmentation, and a drug interaction that markedly reduces oral naltrexone exposure. It has no EMA or MHRA authorisation. Compounded or research-chemical PT-141 sold online as lyophilised powder or nasal spray falls outside the approval and lacks verified identity or sterility.
The Vyleesi label specifies storage of the autoinjector at room temperature, protection from light, and disposal after a single use, and the pharmacy dispensing record captures lot and expiry. Compounded or unlicensed PT-141 powder has no regulator-reviewed guidance; peptide solutions degrade with heat, light, and freeze-thaw cycling, and reconstituted vials have no established beyond-use time outside a pharmacy label. Because the label warns about blood-pressure effects with closely spaced administration and about cumulative skin darkening, the timing between administrations and any pigmentation changes are the details worth recording. A dose log capturing product source, lot, route, time, and observed effects, together with an inventory record, supports that tracking.
- Category
- Sexual health
- Routes represented
- Subcutaneous (SubQ)
- Approximate library half-life
- 2.7 hours; formulation-dependent and not dosing guidance
- Storage context
- Follow the dispensed product or pharmacy label; storage and beyond-use time vary by formulation.
Published literature
No verified PubMed or DOI link is available for this entry.
Safety evidence
Common or reported: nausea, flushing, injection-site reactions, headache, vomiting.
Serious or important: transient blood-pressure increase, heart-rate reduction, persistent focal hyperpigmentation.
Safety evidence sourceInteraction evidence
These are general, pairwise evidence notes. Green identifies the potential-synergy category, while Lv3/Lv2/Lv1 communicates evidence strength; it does not guarantee benefit or cancel a safety warning.
Common questions
Is PT-141 FDA-approved?
Yes, as bremelanotide under the brand name Vyleesi, approved in June 2019 for premenopausal women with acquired, generalised hypoactive sexual desire disorder. The approval covers only the prefilled subcutaneous autoinjector and only that indication; the label states it is not indicated for men or postmenopausal women. PT-141 sold as research-chemical powder or nasal spray is not covered by the approval and is an unapproved drug.
Does PT-141 work for men?
Early-phase studies in the 2000s reported erections in men with erectile dysfunction after intranasal bremelanotide, but development for men was discontinued after blood-pressure concerns and the programme shifted to women. No phase 3 trial in men was completed and no regulator has approved the drug for male use. The Vyleesi label explicitly states that it is not indicated for men.
What are the side effects of PT-141?
In the phase 3 trials the most common adverse reactions were nausea, flushing, injection-site reactions, headache, and vomiting, with nausea by far the most frequent and the main reason for stopping. The label warns of transient increases in blood pressure with decreases in heart rate after each dose, and of focal hyperpigmentation of the face, gums, or breasts that may not fully resolve, more likely with darker skin and frequent administration.
Does PT-141 interact with other medications?
The label reports that bremelanotide slows gastric emptying and can reduce absorption of some oral drugs, and specifically that it substantially decreases exposure to oral naltrexone, risking failure of alcohol or opioid dependence treatment. Because it raises blood pressure transiently, the label also identifies uncontrolled hypertension and known cardiovascular disease as reasons the drug was not studied and is not recommended.
What is the difference between PT-141 and Melanotan II?
PT-141 (bremelanotide) is derived from Melanotan II by converting the terminal amide to a carboxylic acid, which shifts the profile toward sexual-desire effects and away from pigmentation, although skin darkening still occurs. Bremelanotide completed controlled trials and holds FDA approval for one indication, whereas Melanotan II never progressed beyond early studies and is the subject of regulator warnings as an illicit tanning agent.
Further reading
- DailyMed, Vyleesi (bremelanotide injection) prescribing information
- FDA, Vyleesi (bremelanotide) original prescribing information, June 2019
- FDA, Vyleesi NDA 210557 approval letter, June 2019
- Kingsberg et al., Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials, Obstet Gynecol 2019
- Simon et al., Long-term safety and efficacy of bremelanotide for hypoactive sexual desire disorder, 2019
Summarised from published literature for reference only, with citations to the source. Evidence is graded as reported and is not a recommendation to combine, dose, or use any compound.
For personal tracking and education only. Not medical advice, diagnosis, or treatment, and not a medical device. Peptides may be prescription-only or unapproved where you live. Consult a licensed healthcare professional.