PT-141 (Bremelanotide)

What it is

PT-141, also known as bremelanotide, is a synthetic cyclic peptide that activates melanocortin receptors (chiefly MC1R and MC4R) rather than acting directly on blood vessels the way PDE5 inhibitors do. The FDA approved it in 2019 under the brand name Vyleesi as a 1.75 mg subcutaneous injection, self-administered via a single-use prefilled autoinjector, for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. It is taken on demand, at least 45 minutes before anticipated sexual activity, with a maximum of one dose per 24 hours and eight doses per month. Two identical phase 3 trials (the RECONNECT program, over 1,200 women) found statistically significant, though modest, improvements in desire and desire-related distress compared with placebo. Notably, the FDA label itself states that the exact mechanism by which Vyleesi improves HSDD is unknown. Common effects include nausea (about 40% of patients), flushing, injection-site reactions, and headache, plus a transient rise in blood pressure and drop in heart rate after each dose. Outside the approved product, PT-141 is also sold as a lyophilized research or compounded powder that must be reconstituted with bacteriostatic water; that use, including any off-label dosing in men, is not FDA-regulated and rests only on community-reported practice, not clinical trial evidence.

Dose ranges

Study-backed ranges carry a source you can open. Community ranges are widely reported but not clinically established - treat them as what people do, not as advice.

Reconstitution & storage

These figures describe community and compounding-vendor practice for lyophilized research-grade PT-141 powder, not the FDA-approved product. Vyleesi, the approved drug, is dispensed as a prefilled, single-use autoinjector and is never reconstituted by the patient or pharmacist at the point of use. Outside that approved product, vendors selling PT-141 as a research or compounded item commonly describe 5 mg, 10 mg, or 20 mg lyophilized vials mixed with roughly 1 to 3 mL of bacteriostatic water to produce a range of working concentrations. These practices are not FDA-regulated, and the purity, sterility, and labeled content of such vials cannot be independently verified. [community]

Interactions & cautions

Vyleesi's FDA label lists uncontrolled hypertension and known cardiovascular disease as contraindications because each dose causes a transient rise in blood pressure (maximal increases of about 6 mmHg systolic and 3 mmHg diastolic, peaking 2 to 4 hours post-dose) and a transient fall in heart rate (up to about 5 bpm), effects that typically resolve within about 12 hours. Bremelanotide also slows gastric emptying, which can reduce the rate and extent of absorption of concomitantly administered oral medications, including drugs that depend on reaching a threshold concentration such as antibiotics; the label specifically warns that it can significantly decrease systemic exposure to oral naltrexone, risking treatment failure in patients using naltrexone for alcohol or opioid use disorder, so combined use is discouraged. A pharmacokinetic study using intranasal bremelanotide (at a higher dose than the approved injectable) found no clinically significant pharmacokinetic interaction with alcohol, though flushing was slightly more frequent. The label does not directly address interaction with hormonal contraceptives despite its general caution about delayed absorption of oral drugs, so that specific question could not be verified. No formal drug-drug interaction data were located for community or research-grade reconstituted PT-141. [study/DailyMed, except where marked community]

Questions people ask

Sources

1. [1]VYLEESI (bremelanotide) injection - FDA-approved prescribing informationlabelFDA-approved indication (HSDD in premenopausal women), the 1.75 mg subcutaneous dose via single-use autoinjector with maximum 1 dose per 24 hours and 8 doses per month, contraindications (uncontrolled hypertension, known cardiovascular disease), the blood pressure/heart rate warning, focal hyperpigmentation and nausea rates, pharmacokinetics (half-life ~2.7 hours, Tmax ~1 hour, ~100% subcutaneous bioavailability), the naltrexone and delayed-gastric-emptying drug interactions, the mechanism of action (nonselective melanocortin receptor agonist, MC1R/MC4R), and storage/handling of the autoinjector.
2. [2]Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials (RECONNECT) PMID 31599840studyDesign and topline results of the two identical RECONNECT phase 3 trials (1.75 mg subcutaneous bremelanotide vs. placebo in 1,267 premenopausal women with HSDD): statistically significant increases in sexual desire and reductions in desire-related distress versus placebo, with nausea, flushing, and headache (each >=10%) as the most common adverse events. Kingsberg SA et al., Obstet Gynecol 2019;134(5):899-908, doi 10.1097/aog.0000000000003500.
3. [3]Long-Term Safety and Efficacy of Bremelanotide for Hypoactive Sexual Desire Disorder (RECONNECT open-label extension) PMID 31599847study52-week open-label extension of RECONNECT (684 of 856 eligible patients enrolled; 272 completed): treatment-emergent adverse events considered related to study drug were nausea (40.4%), flushing (20.6%), and headache (12.0%), with sustained improvement in sexual function measures and no new safety signals. Simon JA et al., Obstet Gynecol 2019;134(5):909-917, doi 10.1097/aog.0000000000003514.
4. [4]Study to Evaluate the Efficacy and Safety of Bremelanotide in Premenopausal Women With HSDD (RECONNECT Study 301) - NCT02333071regulatoryRegistered phase 3 trial design and sponsor (Palatin Technologies), the 1.75 mg subcutaneous as-needed dosing regimen (max 1 dose/24h), enrollment (723 enrolled, 653 randomized into the double-blind phase), and primary outcome measures (FSFI desire domain, FSDS-DAO item 13) for RECONNECT study 301.
5. [5]Study to Evaluate the Efficacy and Safety of Bremelanotide in Premenopausal Women With HSDD (RECONNECT Study 302) - NCT02338960regulatoryRegistered phase 3 trial design and enrollment (714 enrolled, 604 dosed in the core study) for the second identical RECONNECT trial, confirming the two-trial phase 3 program structure underlying the FDA approval.
6. [6]Bremelanotide, CID 9941379 - PubChem Compound Summary (properties)referenceChemical identity of bremelanotide/PT-141: molecular formula C50H68N14O10, molecular weight ~1025.2 g/mol, and IUPAC name, confirming it as a cyclic heptapeptide.
7. [7]Bremelanotide, CID 9941379 - PubChem Compound Summary (synonyms)referenceCAS registry number 189691-06-3 and UNII 6Y24O4F92S for bremelanotide, and confirmation that PT-141, PT 141, and Vyleesi are recognized synonyms for the same compound.
8. [8]Bremelanotide - LiverTox: Clinical and Research Information on Drug-Induced Liver InjuryreferenceHepatotoxicity likelihood classification (category D: possible rare cause of clinically apparent liver injury), description of a single published case of acute hepatitis after repeated dosing, and the statement that no acute liver failure or chronic liver injury has been attributed to bremelanotide within limited clinical experience.
9. [9]Bremelanotide for Treatment of Female Hypoactive Sexual Desire (narrative review) PMID 35076581reviewNarrative review confirming bremelanotide's melanocortin receptor agonist mechanism, the 1.75 mg on-demand subcutaneous dosing at least 45 minutes before sexual activity, and improvement in desire, arousal, and orgasm scores versus placebo. Edinoff AN et al., Neurol Int 2022;14(1):75-88, doi 10.3390/neurolint14010006.
10. [10]PT-141 Dosing Calculator - Reconstitution & Units (Peptide Protocol Wiki)communityCommunity-reported vial sizes (5/10/20 mg), bacteriostatic-water reconstitution ratios and resulting concentrations, off-label dose ranges (0.5-2 mg), and post-reconstitution refrigerated storage/use-by practice for research-grade PT-141; the page itself distinguishes this from the FDA-approved Vyleesi autoinjector.
11. [11]PT-141 (Bremelanotide) Dosage Guide: Reconstitution and Research Protocol (Know Your Peptide)communityCommunity-reported 10 mg and 5 mg vial reconstitution with bacteriostatic water and resulting concentrations, off-label research dose ranges (0.5-2 mg), and lyophilized-vs-reconstituted storage conditions and use-by windows.