PT-141 (Bremelanotide)

PT-141 (bremelanotide) is a peptide best known for boosting sexual desire and arousal — and unlike Viagra, which works on blood flow, it acts in the brain's desire pathways. It's FDA-approved as Vyleesi for one specific group: premenopausal women with low sexual desire (HSDD). Use in men, postmenopausal women, or for anything else is off-label and not backed by that approval. Given as a small injection under the skin.

PT-141 (bremelanotide, Vyleesi) is FDA-approved for low sexual desire (HSDD) in premenopausal women. The pivotal Phase 3 RECONNECT trials (about 1,267 premenopausal women) reported statistically significant improvements versus placebo on sexual-desire and desire-related-distress measures over 24 weeks, which is the basis for approval. An earlier study of an intranasal form reported enhanced erectile response in men, but that formulation was not carried to approval. The strong trial evidence is specifically in premenopausal women; use in men or postmenopausal women is extrapolation, not direct trial evidence.

FDA-approved as Vyleesi (bremelanotide injection/0.3 mL pre-filled SC autoinjector) under NDA 210557, approved June 21, 2019. FDA-approved indication is narrow: premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD). Not FDA-approved for: postmenopausal women, men (any sexual function indication), or any other condition. Sponsor: originally Palatin Technologies; commercialized by AMAG Pharmaceuticals (later Cosette Pharmaceuticals after the 2020 acquisition). Not DEA-scheduled. Not listed in the WADA 2026 Prohibited List — confirmed by direct text-search of the canonical PDF on 2026-05-04 (zero matches for bremelanotide, melanocortin, MC4, α-MSH, melanotan, or PT-141 in the body or alphabetic index). Currently sold as Vyleesi (FDA-approved, prescription-only) and as a research peptide via compounding pharmacies and research-supply chains for off-label use (men, postmenopausal women, general libido contexts).

Vyleesi is prescription-only and FDA-approved only for premenopausal women with HSDD; nausea is the most common reported side effect (about 40% of users in trials), and the label warns about transient blood pressure elevation, contraindicates uncontrolled hypertension and pregnancy, and is not listed in the WADA prohibited list. VialWise is a research and educational reference, not medical advice — consult a licensed professional.

⚠️ For research and educational purposes only. Bremelanotide is FDA-approved as Vyleesi for premenopausal women with hypoactive sexual desire disorder (HSDD). Information in this entry is informational, not medical advice. Always confirm dose calculations with the in-app calculator and consult appropriate professional guidance before any protocol decisions.

⚠️ Precision matters at small draws. PT-141 (research-community formulations) at typical reconstitution concentrations produces draws in the range on a U-100 syringe. The FDA-approved Vyleesi pre-filled autoinjector eliminates this concern — but research-community vial-and-syringe use requires careful unit-count verification. Always verify draws against the in-app calculator.

⚠️ PT-141's FDA-approved indication is narrow: premenopausal women with HSDD. The FDA-approved Vyleesi labeling specifically covers premenopausal women with acquired, generalized HSDD that is not due to a co-existing medical or psychiatric condition, relationship problems, or medication effects. The approved indication does not cover: postmenopausal women, men (any indication including erectile dysfunction or libido), or any other condition. Most research-community PT-141 use is for off-label indications (men's libido, postmenopausal women, general sexual function) — operating outside the FDA-approved evidence base for those populations and outside Vyleesi's prescriber framework. The pivotal RCT efficacy data (Kingsberg 2019 RECONNECT)[¹] is in premenopausal women specifically; extrapolation to other populations is inference, not direct evidence.

⚠️ PT-141 acts centrally, not peripherally — distinct from PDE5 inhibitors (sildenafil/Viagra, tadalafil/Cialis, vardenafil). The mechanism difference matters practically: PDE5 inhibitors enhance erectile response when sexual stimulation is already present (peripheral vasodilation in response to NO/cGMP signaling); PT-141 acts on the brain's sexual desire and arousal centers (hypothalamic MC4R) and can produce effects in the absence of preceding sexual stimulation. The two drug classes are not interchangeable, are mechanistically complementary rather than competitive, and have meaningfully different side-effect profiles. Researchers comparing PT-141 to PDE5 inhibitors should be explicit with themselves about the mechanism distinction.

PT-141 (bremelanotide) is a synthetic cyclic heptapeptide melanocortin receptor agonist. The molecule was developed by Palatin Technologies as an analog within the broader Melanotan II program — Melanotan II itself is a synthetic α-MSH (alpha-melanocyte-stimulating hormone) analog originally developed for sunless tanning research. PT-141 is structurally derived from Melanotan II but engineered for selective melanocortin receptor activity (primarily MC4R, secondarily MC3R) with reduced effects at the melanin-producing MC1R receptor responsible for tanning. The compound's pharmacological activity is central — it acts on melanocortin receptors in the hypothalamus, particularly the medial preoptic area, where MC4R activation is associated with dopamine release and downstream effects on sexual desire and arousal pathways.[²][³]

Mechanism — central vs peripheral. This is the key conceptual feature distinguishing PT-141 from the PDE5 inhibitor class (sildenafil, tadalafil, vardenafil). PDE5 inhibitors enhance erectile function peripherally through nitric-oxide-mediated vasodilation in the corpus cavernosum — they require pre-existing sexual stimulation to work, because NO release is downstream of the sexual stimulation signal. PT-141 acts upstream of sexual stimulation, in the hypothalamic centers that generate sexual desire and arousal in the first place. The practical consequences: - PT-141 can produce sexual desire and arousal in the absence of preceding stimuli; PDE5 inhibitors cannot. - PT-141 is effective in central / desire-disorder contexts (HSDD) where PDE5 inhibitors are not. This is the basis for the Vyleesi indication: PDE5 inhibitors don't address low desire — bremelanotide does. - PT-141 has different side effects — nausea, flushing, transient blood pressure elevation (central + peripheral autonomic effects), focal hyperpigmentation with repeated use (residual MC1R activity), and headache; PDE5 inhibitors produce visual disturbances, headache, flushing, and dyspepsia from peripheral PDE5/PDE6 activity. - The two drug classes can be combined (in the appropriate patient under specialist supervision) — they target complementary mechanisms.

Pivotal clinical evidence — RECONNECT studies. The FDA approval of Vyleesi was based primarily on the RECONNECT trial program — two identical phase 3, randomized, double-blind, placebo-controlled, multicenter trials in premenopausal women with HSDD (Kingsberg et al., *Obstetrics & Gynecology*, 2019, n=1267 pooled).[¹] Co-primary endpoints: change in Female Sexual Function Index–Desire Domain (FSFI-D) score and change in Female Sexual Distress Scale–Desire/Arousal/Orgasm (FSDS-DAO) Item 13 score, measured at week 24. Both endpoints met statistical significance favoring bremelanotide (FSFI-D effect size 0.39; FSDS-DAO effect size 0.27). Responder rates per the General Assessment Questionnaire: 58.3% / 58.2% bremelanotide vs 36.1% / 35.4% placebo across the two studies. Safety profile: nausea, flushing, and headache reported in ≥10% of bremelanotide users vs lower rates in placebo arms. The RECONNECT evidence base is in premenopausal women with HSDD specifically — does not directly address efficacy in men or in postmenopausal women.

Earlier development context — erectile dysfunction. PT-141 was originally studied as an erectile dysfunction treatment using intranasal administration. The Diamond 2004 laboratory study reported that intranasal PT-141 enhanced erectile response in men with erectile dysfunction who were already responsive to sildenafil.[²] The intranasal formulation was eventually abandoned in favor of the SC autoinjector approach used for Vyleesi; the ED indication was not pursued through to FDA approval, though research-community use of PT-141 for ED in men persists outside the FDA-approved framework.

Regulatory status (US). Vyleesi is FDA-approved as a prescription drug for premenopausal women with HSDD (NDA 210557, June 21, 2019).[⁴] PT-141 is not a DEA-scheduled controlled substance. Off-label use of bremelanotide (men, postmenopausal women, general libido use cases) operates outside the FDA-approved indication but is not a controlled-substance offense — it is a prescriber-discretion matter. Compounded research-community PT-141 (sold as or lyophilized vials for SC reconstitution) operates in the broader research-peptide regulatory framework that applies to most peptides covered elsewhere in this library.

Regulatory status (sport — WADA). PT-141 / bremelanotide is not listed in the 2026 WADA Prohibited List.[⁵] Direct text-search of the canonical 2026 WADA pdf (downloaded and archived at `docs/legal/wada-2026-prohibited-list.pdf` on 2026-05-04) returned zero matches for bremelanotide, melanocortin, MC4, α-MSH, melanotan, or PT-141 across either the body or the alphabetic index. This is a notable absence — most peptide hormones with regulatory consequences are S2-listed; PT-141's narrow sexual-function indication and absence of athletic-performance evidence may explain the negative listing. Researchers competing in WADA-tested sport should still confirm against the most recent annual Prohibited List edition before any competitive event, particularly given the WADA list's annual updates and PT-141's growing research-community footprint.

Common research interests. PT-141 is used in three meaningfully distinct contexts:

1. HSDD treatment in premenopausal women (FDA-approved indication). The Vyleesi-labeled use case; supported by the RECONNECT phase 3 evidence.[¹][⁴] 2. Off-label libido / sexual function support in men. The Diamond 2004 evidence base[²] addresses ED specifically (men responsive to sildenafil); broader research-community use of PT-141 for general libido in men extends beyond this published evidence. 3. Off-label libido / sexual function support in postmenopausal women. Operates outside the RECONNECT trial population; supporting evidence is essentially extrapolation.

In all three contexts, PT-141 is administered SC as needed (PRN), 45 minutes before anticipated sexual activity — not chronically daily-dosed.

Commonly reported

• Nausea — most common side effect; reported in ~40% of bremelanotide users (vs ~6% placebo); typically occurs within 30–60 minutes of injection and may last 2–4 hours; severity ranges from mild to severe enough to discontinue
• Flushing — ~20% of users; transient, typically within first hour
• Injection site reactions — local pain, redness, mild swelling
• Headache — ~10–15% of users
• Vomiting — uncommon but reported; typically associated with severe nausea
• Transient blood pressure elevation — typically peaks 2–4 hours post-injection; may persist 4–10 hours; clinically significant in patients with pre-existing hypertension
• Focal hyperpigmentation — uncommon; typically with repeated dosing; reflects residual MC1R activity in melanocytes; reported particularly in face, gingiva, and breasts
• Headache, fatigue — variable; typically transient

Serious

• Severe persistent nausea or vomiting interfering with hydration
• Severe headache, vision changes, neurological symptoms — possible hypertensive event
• Severe sustained blood pressure elevation
• Severe allergic reactions

Uncontrolled hypertension or known cardiovascular disease — PT-141's BP-elevation effect contraindicated

Hypersensitivity to bremelanotide or any product component

Pregnancy — Category X; bremelanotide is contraindicated in pregnancy

Pregnancy and lactation: contraindicated per Vyleesi label.[⁴]

Cardiovascular disease / hypertension: caution; assess cardiovascular risk before initiating.

Concurrent nitrate medications: caution (BP/cardiovascular interaction).

Active or recent malignancy: theoretical contraindication; particularly melanoma given MC1R activity.

Regulatory note (US): Vyleesi is FDA-approved prescription-only for premenopausal women with HSDD; off-label use in men or postmenopausal women is a prescriber-discretion matter (not a DEA-scheduled offense like testosterone, not a federal-distribution offense like HGH).

Regulatory note (sport): PT-141 / bremelanotide is not listed in the WADA 2026 Prohibited List.[⁵] This may change in future annual editions; researchers competing in WADA-tested sport should confirm against the most recent edition.

Melanocortin receptor agonist

a compound that activates the receptors controlling pigmentation and other effects.

HSDD

Hypoactive sexual desire disorder; persistent low sexual desire that causes distress, addressed by the FDA-approved indication for Vyleesi in premenopausal women.

PDE5 inhibitor

A class of drugs (such as sildenafil/Viagra) that work on blood flow in the body to support erectile function, mechanistically distinct from PT-141's action in the brain.

Peptide

A short chain of amino acids, the building blocks of proteins. Many compounds in this library are peptides.

Subcutaneous

An injection into the fatty layer just under the skin, rather than into a muscle or vein.

1. Kingsberg SA, Clayton AH, Portman D, Williams LA, Krop J, Jordan R, Lucas J, Simon JA. (2019). Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials. Obstetrics & Gynecology, 134(5):899–908.(PMID 31599840 · NCT02333071)
2. Diamond LE, Earle DC, Rosen RC, Willett MS, Molinoff PB. (2004). Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic properties and pharmacodynamic effects of intranasal PT-141, a melanocortin receptor agonist, in healthy males and patients with mild-to-moderate erectile dysfunction. International Journal of Impotence Research, 16(1):51–59.(PMID 14963471)
3. Edinoff AN, Sanders NM, Lewis KB, Apgar TL, Cornett EM, Kaye AM, Kaye AD. (2022). Bremelanotide for Treatment of Female Hypoactive Sexual Desire. Neurology International, 14(1):75–88.(PMID 35076581)
4. AMAG Pharmaceuticals (originally; now Cosette Pharmaceuticals). Vyleesi (bremelanotide injection) prescribing information. US Food and Drug Administration. NDA 210557, originally approved June 21, 2019.
5. World Anti-Doping Agency. The 2026 Prohibited List, International Standard (effective 1 January 2026). Canonical PDF: wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf (linked from the WADA landing page; local archival copy in `docs/legal/wada-2026-prohibited-list.pdf`). PT-141 / bremelanotide is not listed in the 2026 WADA Prohibited List.

• Testosterone — discussed together in this entry's stacks section
• Afamelanotide — same mechanism class
• Melanotan II — same mechanism class
• Clomiphene / Enclomiphene — shared research area
• Gonadorelin — shared research area
• HCG (Human Chorionic Gonadotropin) — shared research area