PT-141

PT-141 (Bremelanotide) is a synthetic cyclic 7-amino-acid melanocortin receptor agonist FDA-approved as Vyleesi for the treatment of acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. It was derived from Melanotan II as a more selective MC4R agonist with reduced pigmentation effects. PT-141 is one of the few FDA-approved peptide compounds in the Peptigrity catalog, with substantial Phase 3 clinical evidence and active prescription distribution.

What is PT-141 and how does the melanocortin-receptor mechanism work?

PT-141 (Bremelanotide) is a synthetic cyclic 7-amino-acid melanocortin receptor agonist derived from Melanotan II, with selective binding to MC4R (melanocortin receptor 4) in the central nervous system. MC4R activation in specific CNS regions modulates sexual desire and arousal pathways through dopaminergic and other neurotransmitter system effects. The selective receptor engagement produces sexual function effects with reduced pigmentation effects compared to the parent Melanotan II. The PT-141 bremelanotide MC4R libido science article covers the receptor pharmacology and trial program in depth.

Evidence level: FDA-approved (Vyleesi for HSDD); Phase 3 clinical evidence (RECONNECT trials)

What does the clinical evidence show for PT-141?

In the Phase 3 RECONNECT trials — 1,267 premenopausal women with acquired, generalized HSDD across two identically designed studies — PT-141 (bremelanotide) produced statistically significant improvements versus placebo in sexual desire (FSFI desire domain) and in desire-related distress (integrated analyses, P<0.001 for both) in sexual desire and reduction in HSDD-related distress versus placebo in premenopausal women with HSDD, supporting FDA approval as Vyleesi in 2019. Effect sizes were modest but consistent. Approved use is as-needed subcutaneous self-administration (1.75 mg autoinjector) at least 45 minutes before anticipated sexual activity.

Sources: Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials, Kingsberg S.A. et al. (optional, non-blocking: complete list), Obstet Gynecol, 2019; VYLEESI (bremelanotide injection) — US Prescribing Information, Cosette Pharmaceuticals (labeler), via DailyMed · Evidence level: FDA-approved (Vyleesi 2019); Phase 3 RECONNECT trials; established prescribing information

How does PT-141 compare to Melanotan II?

PT-141 is the selective MC4R agonist derived from Melanotan II as a focused sexual function compound. PT-141 has FDA approval (Vyleesi for HSDD) and a defined clinical use case; MT-2 has broader melanocortin receptor binding producing varied effects including pigmentation, sexual function, and appetite suppression.

What are the documented side effects of PT-141?

The most common Vyleesi side effects in Phase 3 trials were nausea (40%), flushing (20%), injection-site reactions (13%), headache (11%), and vomiting (5%). Less common but clinically relevant side effects include transient blood-pressure increases with a reduced heart rate after each dose — peak effects around 6 mmHg systolic / 3 mmHg diastolic, usually back to baseline within 12 hours — which is why Vyleesi is contraindicated in uncontrolled hypertension or known cardiovascular disease and focal hyperpigmentation — including of the face, gingiva, and breasts — in 1% of patients dosing up to 8 times per month, rising to 38% with daily dosing for 8 days, and more likely in patients with darker skin. Nausea led 8% of Vyleesi-treated patients to discontinue the trials (versus none on placebo), and 13% required anti-emetic therapy.

Source: VYLEESI (bremelanotide injection) — US Prescribing Information, Cosette Pharmaceuticals (labeler), via DailyMed · Evidence level: phase 3 (RECONNECT) safety data extensive; FDA prescribing information detailed

What is the regulatory status of PT-141?

PT-141 (Bremelanotide) is FDA-approved as Vyleesi for hypoactive sexual desire disorder in premenopausal women. It is available by prescription through licensed pharmacies under specific prescribing parameters. Research-grade PT-141 is sold by third-party laboratories for laboratory use — that is distinct from the FDA-approved Vyleesi product. Regulatory context in are peptides legal regulatory status by country.

Why does PT-141 vendor verification matter even with FDA approval?

Because the FDA approval applies to Vyleesi specifically — not to research-grade PT-141 sold by third-party laboratories. Identity is the sharp edge here: research-grade PT-141 and Melanotan II differ by about one Dalton (free acid vs amide), so telling them apart requires quality mass-spectrometry data — an HPLC purity number alone cannot do it. Compare vendors against the independent PT-141 lab tests on file, and see the where to buy PT-141 purity and identity checks guide for the full framework. Research-grade material is subject to wider purity variance, occasional underdosing, and inconsistent endotoxin control. The structural distinction between PT-141 and the related Melanotan II requires mass spectrometry verification — mislabeling between the two occurs in research-grade markets. Guidance in how-to-test-peptides hub.

Sources: Bremelanotide — compound identity, PubChem (NCBI), PubChem, 2026; Melanotan II — compound identity, PubChem (NCBI), PubChem, 2026

How does Peptigrity verify PT-141 vendors?

Peptigrity collects independent third-party Certificates of Analysis for PT-141 from shops' official channels and verifies each for authenticity before publishing. Because shops choose which COAs to publish, results reflect the batches shops have made public rather than every production batch — a selection bias we state openly. A community-funded Testing Grant to purchase and test vials anonymously is in development. Tests in the database come from independent labs such as Janoshik Analytical, Freedom Diagnostics, and Chromate. Methodology in how we calculate trust scores.

Frequently asked questions

What does PT-141 do?

PT-141 (Bremelanotide, Vyleesi) is FDA-approved for hypoactive sexual desire disorder in premenopausal women, acting through selective MC4R agonism to modulate central nervous system sexual desire pathways. It produces effects on sexual desire and arousal through CNS mechanisms rather than direct vascular effects.

Is PT-141 FDA-approved?

Yes, as Vyleesi for hypoactive sexual desire disorder in premenopausal women. PT-141 is one of the few FDA-approved peptide compounds in the Peptigrity catalog. Research-grade PT-141 is distinct from the FDA-approved Vyleesi prescription product.

Is PT-141 legal to purchase?

Vyleesi is available by prescription. Research-grade PT-141 is legal to purchase as a research chemical for laboratory use in most jurisdictions, but is not the FDA-approved prescription product. Country breakdown in peptide legal status guide.

How does PT-141 differ from Melanotan II?

PT-141 is the FDA-approved selective MC4R agonist derived from Melanotan II; MT-2 has broader receptor binding producing pigmentation effects as well as sexual function effects. PT-141 has the focused mechanism and regulatory approval; MT-2 has broader but unapproved effects.

Does PT-141 work for men?

The FDA approval is specifically for premenopausal women with HSDD — the label's Limitations of Use state it is not indicated for HSDD in postmenopausal women or in men, nor to enhance sexual performance. Research-grade PT-141 use in men is community-driven and not FDA-evaluated for male sexual function indications. Anyone considering use should consult a licensed physician about evidence-based options.

Source: VYLEESI (bremelanotide injection) — US Prescribing Information, Cosette Pharmaceuticals (labeler), via DailyMed

How can I verify a PT-141 vendor is selling real product?

Independent third-party HPLC certificate of analysis from a lab the vendor does not own or pay, with mass spectrometry identity confirmation distinguishing PT-141 from the related Melanotan II. COA interpretation in red flags in peptide certificates of analysis.

Does Peptigrity recommend a PT-141 dose?

No. The Vyleesi prescribing information specifies 1.75 mg subcutaneously, as needed, at least 45 minutes before anticipated sexual activity — with no more than one dose in 24 hours and no more than 8 doses per month recommended. Research-grade use is not FDA-approved. Peptigrity is an independent review platform, not a medical authority. Anyone considering PT-141 should consult a licensed physician about the prescription Vyleesi product.

Source: VYLEESI (bremelanotide injection) — US Prescribing Information, Cosette Pharmaceuticals (labeler), via DailyMed

This section is for educational and informational purposes only and does not constitute medical advice. PT-141 (Bremelanotide) is FDA-approved as Vyleesi for hypoactive sexual desire disorder in premenopausal women. Research-grade PT-141 sold for laboratory use is not the FDA-approved prescription product. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.