# Bremelanotide: full monograph (Bremelanotide Rx)
> Source page: https://bremelanotiderx.com/monograph

Status: FDA-approved drug
Disclosure: Bremelanotide (PT-141) is FDA-approved as Vyleesi for acquired hypoactive sexual desire disorder in premenopausal women. 'PT-141' vials sold outside licensed pharmacies are not the approved product.

## Key facts
- Status: FDA-approved drug
- SC bioavailability: ~100% (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Volume of distribution: 25.0 L (mean) (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Clearance: 6.5 L/hr (CL/F) (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Protein binding: 21% (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Dose plateau: Cmax plateaus at 7.5 mg SC (~4.3x approved dose) (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Excretion: 64.8% urine, 22.8% feces (radiolabel) (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Class: Melanocortin receptor agonist (cyclic heptapeptide alpha-MSH analog) (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Approved use: Acquired, generalized HSDD in premenopausal women (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Explicitly not indicated: Men; postmenopausal women; enhancing sexual performance (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Dose: 1.75 mg SC autoinjector, at least 45 min before activity (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Half-life: About 2.7 h (range 1.9 to 4.0) (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Tmax: About 1.0 h (range 0.5 to 1.0) (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Desire effect vs placebo: +0.30 and +0.42 points (scale 1.2 to 6.0); integrated +0.35 (source: https://pmc.ncbi.nlm.nih.gov/articles/PMC6819021/)
- Satisfying sexual events: No significant change vs placebo in either phase 3 trial (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Nausea rate: 40.0% vs 1.3% placebo (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Key contraindication: Uncontrolled hypertension or known cardiovascular disease (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)
- Molecule: C50H68N14O10, MW 1025.2 (free base), PubChem CID 9941379 (source: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22VYLEESI%22&limit=1)

## Overview
Bremelanotide is the peptide the gray market calls PT-141, and it is one of the few compounds in this fleet with a real FDA approval: Vyleesi, approved June 21, 2019, a subcutaneous autoinjector for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. The approval is genuine and the numbers behind it are modest, and this page gives both facts equal weight. In the two phase 3 trials, desire scores rose 0.5 and 0.6 points on a scale that runs from 1.2 to 6.0, versus 0.2 on placebo: a placebo-adjusted difference of 0.30 and 0.42 points. The number of satisfying sexual events did not significantly change. Both facts sit in the current label.
Three more label facts frame everything on this page. First, the boundary: Vyleesi is not indicated for postmenopausal women or men, and not indicated to enhance sexual performance; those words are the label's, not ours. Second, the tolerability trade: 40% of treated women reported nausea. Third, the market inversion: most 'PT-141' sold online is a compounded or research-grade vial aimed at men and at performance, which is exactly the population and purpose the label rules out, resting on early-phase trials from a program FDA says never led to an approved product.

## About bremelanotide (PT-141)
Bremelanotide is a synthetic cyclic heptapeptide, Ac-Nle-cyclo-(Asp-His-D-Phe-Arg-Trp-Lys-OH), molecular weight 1025.2, an analog of the natural pigmentation hormone alpha-MSH. PT-141 is its original laboratory code from Palatin Technologies, which developed it and out-licensed North American rights to AMAG Pharmaceuticals for the approval; the application is now held by Cosette Pharmaceuticals. The lineage is unusually colorful: the family's sexual effects were discovered by accident during University of Arizona research on the tanning peptide Melanotan-II, when erections turned up as a side effect.
Development ran roughly 20 years and changed shape twice. Early trials, including the male erectile dysfunction program, used an intranasal spray; FDA's review records that the women's program moved to subcutaneous injection because systemic exposure through the nose was too variable. The approved product is therefore a fixed-dose 1.75 mg autoinjector, and no nasal or oral bremelanotide product has ever been approved.

## Regulatory status: what the approval covers
Drugs@FDA lists exactly one bremelanotide product: Vyleesi (NDA 210557), a prescription 1.75 mg/0.3 mL single-dose autoinjector, approved June 21, 2019 as a new molecular entity. The indication is specific: premenopausal women with acquired, generalized HSDD, meaning low desire that developed after a period of normal desire, occurs regardless of partner or situation, causes marked distress, and is not explained by another condition, the relationship, or a medication. The label then draws the line in its Limitations of Use: not for HSDD in postmenopausal women, not for men, not to enhance sexual performance.
Everything sold as 'PT-141' outside that autoinjector, including every research-chemical vial and every compounded nasal spray, is unapproved by definition. FDA's own words about compounded drugs apply: they are not FDA-approved, and FDA does not verify their safety, effectiveness or quality before marketing. The earlier erectile dysfunction development programs, in FDA's summary, did not lead to approved products.

## Mechanism of action: melanocortin receptors
Bremelanotide is a melanocortin receptor agonist that activates several receptor subtypes nonselectively, with a potency order of MC1R, MC4R, MC3R, MC5R, MC2R; at therapeutic doses the label calls binding to MC1R and MC4R most relevant. MC4R is expressed on neurons across the central nervous system and sits at the center of appetite and autonomic regulation; MC1R is the melanocyte receptor that drives pigmentation. That receptor map explains this drug's signature effects better than any marketing page: MC4R activation plausibly links to the desire signal, and also to the transient blood pressure rise and nausea; MC1R explains why repeated dosing can darken skin. The label is blunt about the gap in the middle: the mechanism by which Vyleesi improves HSDD is unknown.
The animal work behind the desire claim is specific and worth stating precisely. In female rats, PT-141 selectively increased solicitation behaviors, the rat's appetitive courting repertoire, without changing lordosis or pacing, and a 2007 review localized the effect to the medial preoptic area. In male rats and nonhuman primates it produces erections, which is how the compound entered human testing in men. MC4R is also an appetite receptor: in two phase 1 trials in obese women, bremelanotide reduced caloric intake by about 400 kcal per day and weight by about a kilogram over about two weeks, a pharmacological signature shared with the melanocortin obesity drugs. A 2021 cryo-EM structure shows bremelanotide seated in MC4R alongside alpha-MSH, using the conserved peptide binding mode.

## Clinical evidence: what the trials measured
The approval rests on RECONNECT: two identical phase 3 randomized, double-blind, placebo-controlled trials (NCT02333071 and NCT02338960) that randomized 1,267 premenopausal women with acquired, generalized HSDD to as-needed bremelanotide 1.75 mg or placebo for a 24-week double-blind core, followed by a 52-week open-label extension. Most women used the drug two to three times per month; the median was 10 injections across the 24 weeks. The co-primary endpoints were a desire score (FSFI desire domain, range 1.2 to 6.0) and a distress score (FSDS-DAO item 13, range 0 to 4).
Both trials hit both co-primaries. Desire rose 0.5 and 0.6 points versus 0.2 on placebo (placebo-adjusted differences of 0.30 and 0.42; integrated 0.35); distress fell 0.7 versus 0.4 (differences of 0.37 and 0.29). The key secondary endpoint, the number of satisfying sexual events, did not significantly change in either trial (integrated P=.630), and under the trials' own statistical hierarchy that made the remaining secondary endpoints supportive and exploratory. The label prints the SSE tables; we reproduce the numbers rather than paraphrase them.
Context that honest reporting requires: premature discontinuation in the double-blind phase was substantially higher on drug than placebo (40% versus 13% in Study 1; 39% versus 25% in Study 2), driven largely by tolerability; the placebo response was high, around 35%, which the investigators note is typical for subjective sexual-function endpoints; and the 52-week extension was uncontrolled, so its larger cumulative changes (desire up 1.25 to 1.30 from core baseline) have no placebo comparison. The phase 2b dose-finding trial, where satisfying sexual events were the primary endpoint, did report a significant SSE gain of +0.7 versus +0.2 per month; that endpoint then failed in both larger, longer phase 3 trials.

## How big is the effect, really?
Here is the honest arithmetic in one place. Desire: +0.35 points more than placebo (integrated), on a desire scale whose full width is 4.8 points (1.2 to 6.0). Distress: -0.33 points more than placebo on a 0-to-4 item. Satisfying sexual events: no significant change (means moved 0.0 versus -0.1 and 0.0 versus 0.0). The trials' own anchor-based responder threshold was a 1.2-point desire gain, which tells you the average treated woman did not reach the change the program itself defined as clinically meaningful; responder analyses (shown as figures in the label) exist because averages this size need them. None of this makes the approval fake. It makes the approval specific: a statistically real, modest average shift in how women score desire and distress, not a change in counted sexual events.

## Does PT-141 work for men?
This is the question the gray market answers with confidence the record does not support. What exists: small, real, mostly 2004-to-2008 studies. Intranasal PT-141 produced RigiScan-verified erections in healthy men and Viagra-responsive ED patients at doses above 7 mg, onset around 30 minutes. Subcutaneous PT-141 produced erections above 1 mg in healthy men, and 4 to 6 mg worked in men with an inadequate sildenafil response. A 7.5 mg intranasal dose added to low-dose sildenafil beat sildenafil alone in 19 patients. The precursor Melanotan-II had already shown the effect in 1998: 8 of 10 men with psychogenic ED, rigid for 38 minutes versus 3 on placebo.
What that evidence is not: late-phase, replicated, or clean. The largest male trial, 342 sildenafil non-responders on 10 mg intranasal bremelanotide (33.5% versus 8.5% response), received an Expression of Concern from the Journal of Urology in 2023; the same author's randomized trial in women with arousal disorder was retracted outright. FDA's review states the earlier ED development programs did not lead to approved products, and records that the program abandoned the intranasal route for variable exposure while FDA's cardiovascular division was flagging blood pressure increases. The label's verdict on men is one sentence: Vyleesi is not indicated for men, and not to enhance sexual performance. A man buying a 'PT-141' vial today is dosing himself with phase 1 era evidence, two integrity-flagged trials, and no approved regimen at all.

## What are 'PT-141' vials sold online?
Two different products share the name. Vyleesi is a prescription, fixed-dose 1.75 mg/0.3 mL sterile solution in a sealed single-use autoinjector, manufactured under an approved NDA. 'PT-141' vials are typically lyophilized peptide sold as a research chemical or compounded preparation: the buyer reconstitutes the powder, chooses a dose, and injects or sprays a product no regulator has verified. FDA's compounding page states the general rule plainly: compounded drugs are not FDA-approved, and FDA does not verify their safety, effectiveness or quality before marketing. This site does not publish reconstitution math for gray vials, deliberately: there is no approved vial format, so any mixing table would be an invented protocol for an unverified product.
The pharmacology adds one more caution the vendors never quote: bremelanotide exposure plateaus. Above roughly 7.5 mg subcutaneous, plasma Cmax stops rising with dose, so megadosing a vial mostly buys more time in the nausea, flushing and blood-pressure window rather than more drug at the receptor. And the known dose-response for harm is real: 38% of women developed focal skin darkening on daily dosing for just 8 days, versus 1% at the labeled at-most-8-per-month cadence.

## Dosage: what the label actually says
The entire approved regimen is one sentence long: inject 1.75 mg subcutaneously in the abdomen or thigh, as needed, at least 45 minutes before anticipated sexual activity; never more than one dose in 24 hours; more than 8 doses per month is not recommended. The label is candid that the timing window is not fully characterized and the duration of effect after a dose is unknown; women in the trials settled at two to three uses per month. There is also a built-in exit: if symptoms have not improved after 8 weeks, the label says to stop.

## How is Vyleesi injected?
Vyleesi comes as a prefilled, single-dose disposable autoinjector: no vial, no syringe drawing, no reconstitution, no dose selection. The user inspects the solution (clear, particle-free), injects into the abdomen or thigh, and discards the device. That design is not a convenience detail; it is the dose control. The fixed 1.75 mg device is what separates the approved product from every scale-and-syringe gray vial sold under the same molecule's name.

## Who should not use bremelanotide?
The label contraindicates Vyleesi in uncontrolled hypertension and in known cardiovascular disease, because every dose transiently raises blood pressure. It is not recommended in patients at high cardiovascular risk even when pressure is controlled. The label also tells patients to avoid it entirely while taking oral naltrexone for alcohol or opioid addiction, since a missed naltrexone exposure can mean relapse. Vyleesi is not indicated in men, in postmenopausal women, or for anyone seeking performance enhancement, and women who could become pregnant should use effective contraception and stop the drug if pregnancy is suspected.

## What are the most serious warnings?
Blood pressure: each dose produces a transient rise, up to 6 mmHg systolic and 3 mmHg diastolic, peaking 2 to 4 hours after injection with heart rate down as much as 5 beats per minute, usually resolving within 12 hours. This is why the label caps dosing at once per 24 hours, and it is the effect FDA's cardiovascular division flagged during review. An ambulatory monitoring study of daily dosing found the daytime averages rose about 2 mmHg, with values back to baseline by 12 to 24 hours.
Focal hyperpigmentation: darkened patches, including on the face, gums and breasts, in 1% of women at labeled frequency, but in 38% with daily dosing for 8 days, plus another 14% among those who continued 8 more days. Darker baseline skin raises the risk, and the label says resolution was not confirmed in all patients after stopping: this one can be permanent. Nausea: 40% of treated women, against 1.3% on placebo; it required anti-emetics in 13% and drove 8% out of the trials, though it improves for most with the second dose.

## What side effects are most common?
From the pooled placebo-controlled trials (Vyleesi versus placebo): nausea 40.0% versus 1.3%, flushing 20.3% versus 0.3%, injection site reactions 13.2% versus 8.4%, headache 11.3% versus 1.9%, vomiting 4.8% versus 0.2%, plus cough, fatigue, hot flush, paraesthesia, dizziness and nasal congestion each in the 2 to 3% range. Nausea starts at a median of one hour post-dose, lasts about two hours, hits 21% of women on the first dose and about 3% on later doses. A dedicated phase 4 study answered the obvious workaround: pre-dosing with 8 mg ondansetron did not reduce the nausea and is not recommended. Overall, 18% of women on drug discontinued for adverse reactions versus 2% on placebo; serious adverse reactions were 1.1% versus 0.5%, including a single open-label case of acute hepatitis whose relationship to the drug could not be excluded.

## Which medicines interact with bremelanotide?
Bremelanotide's main interaction mechanism is mechanical: it slows gastric emptying, which can slow and reduce absorption of anything swallowed around the same time. The label singles out two consequences. Avoid Vyleesi while taking oral drugs that need threshold concentrations to work, such as antibiotics. And do not combine it with oral naltrexone taken for alcohol or opioid addiction, because bremelanotide can cut naltrexone exposure enough to cause treatment failure. In interaction studies, most tested oral drugs were unaffected to any clinically relevant degree; naltrexone and indomethacin were the exceptions.

## What about pregnancy?
Vyleesi is a drug to stop before pregnancy, not during it: the label tells women to use effective contraception and discontinue if pregnancy is suspected. The animal signal is taken seriously because no safe lower bound was found: fetal harm occurred in pregnant dogs at 16 times the human exposure and developmental delays in mouse offspring at 125 times, with no developmental no-effect level established in either species. Human data are thin: 7 pregnancies occurred across the trials with no major congenital anomalies reported, and a pregnancy exposure registry exists to collect more.

## How should Vyleesi be stored?
Store at or below 25 C (77 F); do not freeze; protect from light. Each autoinjector is single-dose and disposable: used once, discarded, never refilled. Discard the device if the solution is cloudy, discolored or contains particles.

## Pharmacokinetics
Bremelanotide is fast in, fast out: after subcutaneous injection it peaks in about an hour (median Tmax 1.0 hour, range 0.5 to 1.0), with a terminal half-life of about 2.7 hours (range 1.9 to 4.0). Subcutaneous bioavailability is essentially complete at about 100%, protein binding is low at 21%, and the peptide is cleared by hydrolysis of its amide bonds, with 64.8% of a radiolabeled dose recovered in urine. Exposure rises less than proportionally with dose and the Cmax plateaus at 7.5 mg, about 4.3 times the approved dose. Renal and hepatic impairment raise exposure up to 2-fold (severe renal) and 1.7-fold (moderate hepatic). The 45-minute pre-activity timing in the label sits just before the plasma peak; the blood pressure effect peaks later, at 2 to 4 hours.

## What we don't know yet
Checked absences, stated as such. No trial has tested bremelanotide against Addyi, the other approved HSDD drug; the comparison page on this site is therefore label-versus-label and meta-analysis-versus-trial, never head-to-head. The duration of effect after a dose is unknown; the label says so. Whether the desire benefit survives past 76 weeks is unmeasured, and the only long-term data (52-week extension) are uncontrolled, with 272 of 684 entrants completing. Long-term hyperpigmentation risk beyond the trial window is not characterized, and the label could not confirm resolution in all affected patients. Male efficacy at any marketed gray-market dose is untested in any modern randomized trial; the male program stopped at small 2004-to-2008 studies, two of which now carry integrity flags. Severe hepatic impairment pharmacokinetics were never studied. The mechanism for the desire effect itself is, in the label's own word, unknown.

## References

## Frequently asked questions

## Related compounds and comparisons

## Study results
| Study | Species/model | n | Duration | Outcome | Effect size |
| --- | --- | --- | --- | --- | --- |
| RECONNECT Study 301 (NCT02333071), Kingsberg 2019 (https://pmc.ncbi.nlm.nih.gov/articles/PMC6819021/) | human (Randomized, double-blind, placebo-controlled phase 3, 1:1) | 628 evaluable MITT (313 BMT / 315 placebo); 723 enrolled | 24 weeks double-blind (+52-week open-label extension) | FSFI-D +0.5 vs +0.2 (p=0.0002); FSDS-DAO Q13 -0.7 vs -0.4 (p<0.0001); SSEs 0.0 vs -0.1, not significant (p=0.764) | Placebo-adjusted: desire +0.30; distress -0.37; SSE null |
| RECONNECT Study 302 (NCT02338960), Kingsberg 2019 (https://pmc.ncbi.nlm.nih.gov/articles/PMC6819021/) | human (Randomized, double-blind, placebo-controlled phase 3, 1:1) | 570 evaluable MITT (282 BMT / 288 placebo); 714 enrolled | 24 weeks double-blind (+52-week open-label extension) | FSFI-D +0.6 vs +0.2 (p<0.0001); FSDS-DAO Q13 -0.7 vs -0.4 (p=0.0053); SSEs 0.0 vs 0.0, not significant (p=0.702) | Placebo-adjusted: desire +0.42; distress -0.29; SSE null |
| RECONNECT 52-week open-label extension, Simon 2019 (https://pmc.ncbi.nlm.nih.gov/articles/PMC6819023/) | human (Uncontrolled open-label extension (descriptive statistics only)) | 684 enrolled of 856 eligible; 272 completed | 52 weeks | No new safety signals; nausea 40.4%, flushing 20.6%, headache 12.0%; FSFI-D +1.25 to +1.30 from core baseline (core-BMT group) vs +0.70 to +0.77 (core-placebo group) | No placebo arm; changes are uncontrolled cumulative shifts |
| Phase 2b dose-finding (NCT01382719), Clayton 2016 (https://pmc.ncbi.nlm.nih.gov/articles/PMC5384512/) | human (Randomized, placebo-controlled, double-blind, 4-arm dose-finding) | 327 in efficacy analysis | 12 weeks | SSEs (primary) +0.7 vs +0.2/month, pooled 1.25/1.75 mg (p=0.0180); FSFI total +3.6 vs +1.9; FSDS-DAO total -11.1 vs -6.8 | SSE +0.5/month placebo-adjusted; 1.75 mg selected for phase 3 |
| Intranasal PT-141 in healthy men and ED patients, Diamond 2004 (https://europepmc.org/article/MED/14963471) | human (Double-blind, placebo-controlled, dose-escalation) | not stated in abstract (two cohorts) | Single doses | RigiScan erectile response significant vs placebo at doses >7 mg; first erection ~30 min; flushing and nausea most common; intranasal Tmax 0.5 h, t1/2 1.85-2.09 h | Dose-dependent erectogenic signal; no efficacy scale reported |
| Subcutaneous PT-141 in healthy men and sildenafil non-responders, Rosen 2004 (https://europepmc.org/article/MED/14999221) | human (Double-blind, placebo-controlled crossover) | not stated in abstract (two cohorts) | Single doses | Significant RigiScan response >1.0 mg in healthy men; significant at 4 and 6 mg in men with inadequate response to sildenafil 100 mg | Erectogenic at doses from 1/10th of the gray market's typical claims |
| Intranasal PT-141 + sildenafil co-administration, Diamond 2005 (https://europepmc.org/article/MED/15833522) | human (Randomized crossover, 3 conditions) | 19 | Single doses | Combination produced significantly greater erectile response than sildenafil alone; no new adverse events | Additive signal at subtherapeutic doses of both agents |
| Intranasal bremelanotide in sildenafil non-responders, Safarinejad 2008 (https://europepmc.org/article/MED/18206919) [Expression of Concern (J Urol, 2023)] | human (Randomized, double-blind, placebo-controlled) | 342 | At least 16 at-home doses | Positive clinical results 33.5% vs 8.5% placebo (p=0.03); more drug-related adverse effects. INTEGRITY FLAG: Journal of Urology Expression of Concern, January 2023 | Largest male trial, now integrity-flagged; treat with caution |
| Intranasal bremelanotide in women with arousal disorder, Safarinejad 2008 (https://europepmc.org/article/MED/18179455) [Retracted (J Sex Med)] | human (Randomized, double-blind, placebo-controlled, fixed dose) | not relied on | not relied on | RETRACTED by the Journal of Sexual Medicine; findings cannot be relied on and are not reported here | None usable; row retained to flag the retraction for readers who encounter this citation elsewhere |
| Melanotan-II in psychogenic ED, Wessells 1998 (https://europepmc.org/article/MED/9679884) | human (Double-blind, placebo-controlled crossover) | 10 | Single doses | Erections in 8 of 10 men; tip rigidity >80% for 38.0 min vs 3.0 min placebo (p=0.0045); nausea, stretching, yawning, decreased appetite | First controlled human evidence for the receptor family |
| Melanotan-II in organic-risk ED, Wessells 2000 (https://europepmc.org/article/MED/11018622) | human (Double-blind, placebo-controlled crossover) | 10 | Single doses | Erections after 12/19 injections vs 1/21 placebo; rigidity >80% 45.3 vs 1.9 min (p=0.047); desire increased; severe nausea after 4/19 injections | Erection plus desire signal, at a real nausea cost |
| PT-141 and female rat solicitation, Pfaus 2004 (https://pmc.ncbi.nlm.nih.gov/articles/PMC454387/) | rat (Controlled laboratory study, ovariectomized hormone-primed rats) | not stated in abstract | Acute | Selective increase in solicitations; no change in lordosis, pacing, motor activity or sexual reward | Behaviorally selective appetitive effect; basis of the desire hypothesis |
| Melanotan-II and proceptive behavior in female rats, 2006 (https://europepmc.org/article/MED/17113634) | rat (Within-subject controlled laboratory study) | 14 (7 + 7) | Acute, repeated tests | Hops, darts and ear wiggling increased with estradiol+progesterone priming; no effect with estradiol alone; lordosis unchanged | Effect requires hormonal context; not a universal desire switch |
| Bremelanotide and body weight in obese women, Spana 2022 (https://pmc.ncbi.nlm.nih.gov/articles/PMC9314948/) | human (Two phase 1 randomized, double-blind, placebo-controlled trials) | 30 (Study A) + 27 (Study B) | 16 days (A); three 4-day periods (B) | Weight -1.3 kg vs placebo (p<0.0001, A); -1.7 vs -0.9 kg (p<0.001, B); caloric intake reduced ~400 kcal/day | Short-term appetite suppression consistent with MC4R agonism; no obesity indication exists |
| MC4R cryo-EM structures with bremelanotide, 2021 (https://pmc.ncbi.nlm.nih.gov/articles/PMC8563965/) | in vitro (Cryo-electron microscopy, receptor-G-protein complexes) | n/a | n/a | Full-length MC4R-Gs structures bound to alpha-MSH, afamelanotide, bremelanotide and THIQ; conserved peptide binding mode | Structural basis for nonselective peptide agonism |

## What we do not know yet
Checked absences, stated as such. No trial has tested bremelanotide against Addyi, the other approved HSDD drug; the comparison page on this site is therefore label-versus-label and meta-analysis-versus-trial, never head-to-head. The duration of effect after a dose is unknown; the label says so. Whether the desire benefit survives past 76 weeks is unmeasured, and the only long-term data (52-week extension) are uncontrolled, with 272 of 684 entrants completing. Long-term hyperpigmentation risk beyond the trial window is not characterized, and the label could not confirm resolution in all affected patients. Male efficacy at any marketed gray-market dose is untested in any modern randomized trial; the male program stopped at small 2004-to-2008 studies, two of which now carry integrity flags. Severe hepatic impairment pharmacokinetics were never studied. The mechanism for the desire effect itself is, in the label's own word, unknown.

## Questions and answers
### Is PT-141 FDA approved?
Yes, as Vyleesi: a 1.75 mg subcutaneous autoinjector approved June 21, 2019 for acquired, generalized hypoactive sexual desire disorder in premenopausal women. It is not approved for men, postmenopausal women, or performance enhancement, and no vial or nasal form of bremelanotide is approved.

Yes, and the boundary is the story. FDA approved bremelanotide as Vyleesi (NDA 210557) on June 21, 2019 for exactly one population and purpose: premenopausal women with acquired, generalized HSDD, low desire that arrived after a period of normal desire, shows up regardless of situation or partner, and causes marked distress. The label's Limitations of Use exclude men, postmenopausal women, and performance enhancement in as many words. The approved product is a fixed-dose autoinjector; Drugs@FDA lists no other bremelanotide product, so every 'PT-141' vial and nasal spray is unapproved by definition. The label even includes an exit rule: stop after 8 weeks without improvement.

### Does PT-141 actually work?
For its approved use, modestly: desire rose 0.30 to 0.42 points more than placebo on a 1.2-to-6.0 scale across two phase 3 trials, and distress fell 0.33 points more. Satisfying sexual events did not significantly change. Real, statistically solid, and small; the label reports all three numbers.

Define work. In two identical phase 3 trials (1,267 women), bremelanotide beat placebo on both co-primary endpoints: desire scores rose 0.5 and 0.6 points versus 0.2 (placebo-adjusted +0.30 and +0.42, integrated +0.35 on a scale spanning 1.2 to 6.0), and desire-related distress fell 0.7 versus 0.4. Those are real effects with p-values under 0.001. The same trials' key secondary endpoint, the count of satisfying sexual events, did not move: 0.0 versus -0.1 and 0.0 versus 0.0, integrated P=.630, and the label prints that table too. Placebo response was high (~35%), dropout on drug was 40% versus 13% in Study 1, and the trials' own responder threshold (a 1.2-point desire gain) was larger than the average change. So: it works, at a size you should know before deciding it matters.

### Does PT-141 work for men or erectile dysfunction?
Unknown at any marketed dose. Small 2004-2008 trials showed real erectile signals (RigiScan-verified), but the program stopped, FDA says it never produced an approved product, the largest male trial got a 2023 Expression of Concern, and a related trial was retracted. Vyleesi's label: not indicated for men.

The honest answer is a graded one. Proof-of-concept evidence exists: intranasal PT-141 produced statistically significant erections above 7 mg (onset ~30 minutes), subcutaneous doses worked above 1 mg in healthy men and at 4 to 6 mg in sildenafil non-responders, and 7.5 mg added to low-dose sildenafil beat sildenafil alone in 19 men. The precursor Melanotan-II produced erections in 8 of 10 men in 1998. But that is where the record stops: no phase 3, no approval (FDA's review says the ED programs 'did not lead to approved products'), an intranasal route abandoned for variable exposure while FDA flagged blood-pressure increases, and integrity problems in the two largest Safarinejad trials: a 2023 Expression of Concern on the 342-man study and an outright retraction of the female arousal trial. The label states Vyleesi is not indicated for men. A man using a gray vial is running a self-experiment on 20-year-old phase 1 evidence.

### What are the odds PT-141 makes me nauseous?
In the trials: 40% overall versus 1.3% on placebo. First dose is the worst (21%), dropping to about 3% on later doses; median onset one hour, duration about two. 13% needed anti-emetics, 8% quit over it, and pre-dosing ondansetron was tested and did not help.

Two in five women reported nausea (40.0% versus 1.3% on placebo), making it the defining tolerability issue. The pattern matters: 21% after the first dose, about 3% after subsequent doses, median onset within an hour, lasting about two hours, and improving for most with the second dose. It was severe enough that 13% used anti-emetic therapy and 8% left the trials over it; vomiting occurred in 4.8%. The obvious workaround was formally tested and failed: 8 mg ondansetron 30 minutes before dosing did not reduce nausea in a 228-woman randomized study, and the label says it is not recommended. Flushing (20.3%) and headache (11.3%) are the other frequent effects.

### Can PT-141 darken my skin permanently?
Yes, possibly. Focal hyperpigmentation (face, gums, breasts) hit 1% at labeled use but 38% with daily dosing for 8 days; darker skin raises the risk, and the label says resolution was not confirmed in all patients after stopping. This is MC1R pharmacology, the tanning receptor, working as designed.

This is the adverse effect most tightly wired to the mechanism: bremelanotide activates MC1R, the melanocyte receptor, most potently of all its targets; it is a chemical cousin of the tanning peptide Melanotan-II. In the phase 3 trials, 1% of women at up-to-8-doses-per-month developed focal hyperpigmentation, including of the face, gingiva and breasts, versus zero on placebo. Under daily dosing for 8 days, 38% developed it, and among women who continued another 8 days, an additional 14% did. Darker baseline skin raises the risk. Most soberly: the label states resolution was not confirmed in all patients after discontinuation. The label's 8-dose monthly cap exists partly for this reason, which is also why gray-market frequent dosing changes the risk math.

### How does Vyleesi compare with Addyi (flibanserin)?
Both treat HSDD, never tested head-to-head. Vyleesi: on-demand injection, 40% nausea, BP contraindications, SSEs unchanged. Addyi: nightly pill, boxed warning around alcohol, CYP3A4 inhibitors and liver disease; meta-analysis found +0.49 satisfying events/month. Different trade-offs.

They are the only two FDA-approved HSDD drugs and they have never been compared in a trial, so any 'which is better' claim is marketing. Vyleesi (2019) is an as-needed 1.75 mg injection at least 45 minutes before activity: desire +0.35 versus placebo integrated, SSEs unchanged, nausea in 40%, contraindicated in uncontrolled hypertension and cardiovascular disease. Addyi (2015) is a 100 mg nightly pill: a 2016 meta-analysis (5,914 women) found +0.49 satisfying sexual events per month, a 0.27-point FSFI-desire gain, and elevated risks of dizziness (RR 4.00), somnolence (RR 3.97) and nausea (RR 2.35), with overall evidence quality graded very low. Addyi carries a boxed warning for hypotension and syncope with alcohol timing rules, contraindicated CYP3A4 inhibitors and hepatic impairment. Both labels share one instruction: stop after 8 weeks if nothing improves.

### Is compounded or research-vial PT-141 the same as Vyleesi?
Same molecule name, different product reality. Vyleesi is a sealed, fixed-dose 1.75 mg autoinjector from an approved NDA. Vials are unverified powder you mix and dose yourself; FDA states compounded drugs are not FDA-approved and their safety, effectiveness and quality are not verified.

The approved product is a prefilled single-use autoinjector delivering exactly 1.75 mg, manufactured under NDA 210557 with FDA-verified content and sterility. Gray 'PT-141' is typically lyophilized powder in a vial, sold as a research chemical or compounded preparation, reconstituted and dosed by the buyer. FDA's general statement applies: compounded drugs are not FDA-approved, and FDA does not verify their safety, effectiveness or quality before marketing. The pharmacology adds irony: plasma exposure plateaus at 7.5 mg, so heroic vial doses mostly extend the nausea and blood-pressure window. This site publishes no reconstitution math for PT-141 vials, because there is no approved vial to calculate for; that is a deliberate editorial decision, explained on the tools page.

### When do you inject Vyleesi, and how long does it last?
Label: at least 45 minutes before anticipated sexual activity, in the abdomen or thigh. Plasma peaks around 1 hour; half-life is about 2.7 hours. How long the desire effect lasts is unknown; the label says the optimal window has not been fully characterized. Max 1 dose/24 h, at most 8 per month.

The label instructs injecting 1.75 mg subcutaneously in the abdomen or thigh at least 45 minutes before anticipated sexual activity, and is unusually candid about what it does not know: the duration of efficacy after each dose is unknown, and the optimal administration window has not been fully characterized; women are told to find their own timing based on experienced effect and nausea. Pharmacokinetics bracket the guess: peak plasma at about an hour, terminal half-life 2.7 hours, blood pressure effect peaking at 2 to 4 hours and resolving by about 12. Hard limits: one dose per 24 hours (the BP effect is the stated reason), and more than 8 doses per month is not recommended.

### Is PT-141 safe if I have high blood pressure?
If it is uncontrolled, the label says no: contraindicated, along with known cardiovascular disease. Every dose transiently raises systolic pressure up to 6 mmHg for a few hours. Controlled hypertension requires a prescriber's risk assessment, and high cardiovascular risk is 'not recommended' territory.

The label contraindicates Vyleesi in uncontrolled hypertension and known cardiovascular disease, and recommends against it in anyone at high cardiovascular risk. The reason is measured, not theoretical: each dose raises systolic pressure up to 6 mmHg and diastolic 3 mmHg, peaking 2 to 4 hours post-dose, with heart rate dipping up to 5 beats per minute, and resolution usually within 12 hours. Ambulatory monitoring during daily dosing showed daytime averages up about 2 mmHg. FDA's cardiovascular reviewers flagged exactly this during the approval, which is why the 24-hour dose spacing exists: stacked doses risk additive pressure effects. This is also a live risk for gray-vial users who dose more often than the label ever studied.

### Is PT-141 an aphrodisiac or performance enhancer?
Not per its own evidence. The label states Vyleesi is not indicated to enhance sexual performance, and in both phase 3 trials the count of satisfying sexual events did not significantly change. The measured effect is a modest average rise in self-scored desire in women with a diagnosed disorder.

The word aphrodisiac implies more events, better performance, universal effect. The record supports none of the three. The label says in plain words that Vyleesi is not indicated to enhance sexual performance, and the phase 3 trials found no significant change in satisfying sexual events. The measured benefit is an average +0.35-point shift in self-rated desire, in premenopausal women meeting diagnostic criteria for acquired generalized HSDD; the rat literature likewise shows a selective effect on solicitation behavior in hormonally primed females, not a general arousal switch. Marketing PT-141 as a couples' enhancement drug inverts what the evidence actually measured.

### Does PT-141 cause weight loss?
It suppressed appetite in two small phase 1 trials in obese women (about 400 kcal/day less, roughly 1 to 1.7 kg over about two weeks) via MC4R, the appetite receptor. No obesity indication exists, dosing was far more frequent than the label allows, and no long-term weight data exist.

There is a real pharmacological signal here, reported honestly: in two phase 1 randomized placebo-controlled trials in obese premenopausal women, repeated bremelanotide dosing cut caloric intake by about 400 kcal per day and produced 1.3 kg (16 days, three-times-daily) and 1.7 versus 0.9 kg (twice-daily) more weight loss than placebo. MC4R agonism regulates appetite, which is the same reason a different melanocortin drug is approved for rare genetic obesity. But note what those trials are not: they used dosing frequencies (2 to 3 doses daily) that the Vyleesi label never permits (8 per month), ran about two weeks, and led to no approval. At label frequency there is no evidence of weight change, and daily dosing is exactly the pattern that produced 38% skin hyperpigmentation.

### Can you drink alcohol with PT-141?
Unlike Addyi, Vyleesi has no alcohol boxed warning. A dedicated study at a 20 mg intranasal dose (2.5x the approved exposure) found alcohol did not change bremelanotide levels and orthostatic events matched ethanol alone. Flushing and headache overlap; the drug still raises blood pressure on its own.

This is one place the Vyleesi record is cleaner than its competitor's. Addyi carries a boxed warning requiring alcohol timing rules because the combination causes hypotension and syncope. Vyleesi's label reports a dedicated crossover study: a 20 mg intranasal bremelanotide dose (about 2.5 times the approved product's Cmax) plus 0.6 g/kg ethanol (roughly three drinks) produced no change in bremelanotide pharmacokinetics and no more abnormal orthostatic blood-pressure drops than ethanol alone; flushing was commoner with the combination than ethanol alone but similar to bremelanotide alone. The same 20 mg dose also cleared QTc testing. None of this makes alcohol a recommendation; it makes the absence of an interaction warning an evidenced absence rather than an untested one.

### What happened to the PT-141 nasal spray?
The early programs, including the male ED trials, used intranasal spray. FDA's review records the switch to subcutaneous injection because nasal systemic exposure was too variable, while FDA cardiologists were flagging blood-pressure rises. No nasal bremelanotide product was ever approved.

Bremelanotide's first decade of human trials, including all the male erectile dysfunction studies, ran through an intranasal spray at 4 to 20 mg. Two documented problems ended that era. FDA's multidiscipline review records that the women's program moved to subcutaneous dosing 'due to variable systemic exposure via the intranasal route', and separately that FDA's clinical team and its Division of Cardiovascular and Renal Products identified blood-pressure increases of about 4 mmHg as a cardiovascular concern requiring a dedicated ambulatory monitoring study. The review also notes the earlier ED programs did not lead to approved products. Today's compounded 'PT-141 nasal sprays' revive the abandoned route, with none of the exposure control that made FDA reject it.

## References
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