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PT-1417 residues (approx.)DHFRWKEach bubble = one amino acid. Size = residue mass. Color = chemical class.Uses closest standard amino acids for non-standard residues.Also known as: PT-141, Vyleesi, bremelanotide acetate
The RECONNECT trials enrolled 1,247 women and produced the first FDA approval for a drug that targets sexual desire at the brain level. The PT-141 peptide (bremelanotide, brand name Vyleesi) is a melanocortin-4 receptor agonist, a cyclic heptapeptide that activates MC4R neurons in the hypothalamus to increase arousal and desire on demand. Nausea affects roughly 40% of users on the first dose, and 18% of trial participants discontinued because of side effects. The approval covers premenopausal women with hypoactive sexual desire disorder (HSDD), though off-label use in men with erectile dysfunction has Phase 2 trial support.
Two Phase 3 trials, 1,247 participants, 24 weeks of data, and one FDA approval. That is the clinical foundation behind the PT-141 peptide. Bremelanotide (CAS 189691-06-3) is a cyclic heptapeptide with a molecular weight of 1,025.2 Da, sold under the brand name Vyleesi as a prefilled autoinjector. The mechanism is unlike anything in the PDE5 inhibitor class. Sildenafil and tadalafil increase blood flow. PT-141 activates melanocortin-4 receptors (MC4R) in the medial preoptic area of the hypothalamus, the region governing sexual motivation. Subcutaneous injection reaches peak plasma concentration within about one hour (Tmax ~1 hour), and functional effects last 6 to 12 hours despite a short 2.7-hour half-life. The RECONNECT trials [1] showed statistically significant improvements in both desire score and distress score versus placebo at 24 weeks. A 52-week extension confirmed sustained efficacy with no new safety signals. Off-label community use is widespread among both sexes; roughly 500+ Reddit threads document male users reporting subjective benefit, though no Phase 3 trial in men has been completed. The FDA label explicitly states bremelanotide is "not indicated for men." Cost is a real barrier. Brand Vyleesi runs about $232 per dose at retail. Research-grade vials from peptide suppliers cost $40 to $80 for a 10 mg vial, but purity and sequence fidelity cannot be verified without independent testing.
PT-141 is a synthetic analog of alpha-melanocyte-stimulating hormone. It binds MC4R, MC3R, and MC1R, though the sexual effects are driven primarily through MC4R activation in the hypothalamus. MC4R is a G-protein coupled receptor concentrated in the medial preoptic area and paraventricular nucleus. When bremelanotide binds MC4R, it triggers a Gq-coupled signaling cascade that increases intracellular calcium and activates downstream dopaminergic pathways. This directly modulates sexual desire and arousal at the central nervous system level, bypassing peripheral vascular mechanisms entirely. Subcutaneous bioavailability is approximately 100% per the FDA prescribing information. After injection, plasma concentration peaks at roughly one hour. The elimination half-life sits at 2.7 hours, but receptor occupancy sustains functional effects for 6 to 12 hours. That disconnect between plasma clearance and duration of action is why single on-demand dosing works. MC1R activation explains the melanocyte-related side effects. Focal hyperpigmentation at injection sites occurred in 1% of Phase 3 participants, and resolution was not confirmed in all cases after stopping. MC3R activation likely contributes to the nausea profile; the area postrema (the brain's emetic center) expresses melanocortin receptors, and 40% nausea incidence tracks with this anatomy.
FDA-approved 1.75 mg SC on-demand for HSDD in premenopausal women. RECONNECT Phase 3 (n=1,247) showed statistically significant improvement in desire and distress scores vs. placebo at 24 weeks. 52-week extension confirmed sustained efficacy with no new safety signals. Only 1.75 mg has Phase 3 RCT support: sub-doses have no validated efficacy data.
RECONNECT Phase 3 trials: two randomized double-blind placebo-controlled studies, n=1,247, 24-week primary endpoint, bremelanotide 1.75 mg SC on-demand; PMID 31599840
Approved only for premenopausal women; FDA explicitly not indicated for men; no Phase 3 male trial data; 18% AE-related discontinuation rate; 40% nausea incidence; no sub-dose (500/1000 mcg) RCT efficacy data; focal hyperpigmentation (1%) may be permanent
Widely used off-label by both sexes. Effective for central desire and arousal. Nausea is the primary barrier: most users start at 500 mcg to test tolerance before titrating. Men report subjective benefit despite off-label status.
Science and community agree on mechanism and efficacy at 1.75 mg. They diverge on dosing: FDA has only one approved dose (1.75 mg), but the community widely uses 500–1,000 mcg sub-doses to manage nausea: a practice with no RCT efficacy validation. Community also extends off-label use to men, which has Phase 2 trial support but no Phase 3 approval.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 500mcg | As needed |
| Moderate | 1mg | As needed |
| Aggressive | 1,750mcg | As needed |
Standard reconstitution for a 10 mg vial: add 2 mL bacteriostatic water. That gives you 5,000 mcg per mL, or 5 mcg per unit on a U100 insulin syringe. At 1,750 mcg (the FDA dose), you'll draw 35 units. At 500 mcg (community test dose), draw 10 units. At 1,000 mcg, draw 20 units. You'll want ondansetron on hand for the first dose. Nausea hits hard the first time and catches people off guard. Inject 45 to 60 minutes before you need it working; don't rush this timing. One vial at this concentration gives you roughly 5 to 6 doses at 1,750 mcg or up to 20 doses at 500 mcg. Store reconstituted solution refrigerated at 2 to 8 degrees Celsius; use within 30 days. If the solution turns cloudy or shows particles, discard it. Rotate injection sites every time (abdomen and thigh are standard). Keep use to eight doses per month maximum.
PT-141 is on-demand, not cycled in the traditional sense. The FDA-mandated max of 8 doses/month and max 1 dose/24 hours is driven by the transient BP elevation profile and focal hyperpigmentation risk: both cumulative with use frequency. No tachyphylaxis was observed in 52-week clinical trials (PMC6819023), confirming that receptor desensitization is not the limiting factor; safety monitoring is.
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Expected: Statistically significant improvements in sexual desire score and distress score per RECONNECT Phase 3 trial data. Onset ~45–60 min, duration ~6–12 hours.
Monitor: Monitor BP within 12 hours of each dose. Inspect injection sites for focal hyperpigmentation after each use. Avoid use if uncontrolled hypertension.
Direct the stream down the glass wall, not onto the powder. Swirl gently until dissolved. Solution should be clear and colorless.
If pre-treating for nausea, take ondansetron 4 mg by mouth 30 to 60 minutes before the PT-141 injection.
At 2 mL BAC water in a 10 mg vial (5,000 mcg/mL): 10 units equals 500 mcg, 20 units equals 1,000 mcg, 35 units equals 1,750 mcg.
Abdomen (2 inches from navel) or outer thigh are standard locations.
Pinch the skin and insert the needle at a 45 to 90 degree angle using a 29 to 31 gauge, 0.5 inch insulin syringe.
Remove the needle and apply light pressure with gauze.
Time your injection at least 45 minutes before anticipated activity. Most users find peak effects between 1 and 4 hours after injection.
Do not exceed 1 dose per 24 hours or 8 doses per calendar month. Store reconstituted vial refrigerated. Rotate injection sites to reduce hyperpigmentation risk.
None: all clinical data based on SC administration
Vyleesi uses a prefilled autoinjector. Research-grade requires reconstitution with BAC water (defaultBacWater: 2.0 mL for 10 mg vial = 5,000 mcg/mL).
Bioavailability likely lower than SC; typical intranasal doses 1–2 mg; onset profile unvalidated
Community reports variable efficacy. Used primarily by those who prefer to avoid injections. Not FDA-approved in this form.
Complementary mechanisms: PT-141 increases central desire via MC4R; PDE5i increases genital blood flow via nitric oxide. Community reports synergistic benefit, especially in men.
PT-141 1,750 mcg SC 45–60 min before; PDE5i at its usual dose. Monitor for additive BP drop.
Community reports enhanced emotional bonding and intimacy when stacked with PT-141. No clinical trial data for this combination.
Oxytocin 24–40 IU intranasal 15–30 min before activity, alongside PT-141.
Pre-treatment reduces PT-141-induced nausea (40% incidence). FDA label acknowledges anti-emetics as a management strategy.
Ondansetron 4 mg PO 30–60 min before PT-141 injection.
Both are non-selective melanocortin agonists (MC1R, MC3R, MC4R). Combining adds risk of additive nausea, BP elevation, hyperpigmentation, and spontaneous erections without meaningful synergy. Redundant mechanism.
Do not combineBremelanotide significantly reduces naltrexone systemic exposure per FDA label: may destabilize addiction treatment. Direct pharmacokinetic interaction. Listed as a contraindication in FDA prescribing information.
Do not combineBremelanotide causes transient BP elevation (~12h); in patients on antihypertensives or with cardiovascular disease, this can create unpredictable BP fluctuations. Use only with physician oversight.
Pricing updated 2026-04-09
Nausea is the headline. In the RECONNECT Phase 3 trials, 40% of bremelanotide-treated participants reported nausea versus 1% on placebo. That is not a minor footnote. On the first dose, nausea can be severe enough to cancel the evening. The 18% discontinuation rate due to adverse events reflects this reality. The nausea comes from melanocortin receptor activation in the area postrema, the same brain region targeted by chemotherapy-induced emesis. Pre-treatment with ondansetron (Zofran) 4 mg taken orally 30 to 60 minutes before injection is the most common community workaround. Eating a light meal and staying hydrated also helps. Most users report that nausea decreases significantly after two to four doses as MC4R partially adapts. Flushing occurred in about 20% of participants. Facial redness can be noticeable to partners. Headache affected 11%. Blood pressure elevation is transient but clinically important. Bremelanotide raises systolic and diastolic BP for up to 12 hours after each dose. For anyone with uncontrolled hypertension or cardiovascular disease, this is a hard contraindication per the FDA label. Even in healthy users, blood pressure should be monitored, particularly within the first 12 hours. Focal hyperpigmentation at injection sites was documented in 1% of Phase 3 participants. This comes from MC1R activation stimulating melanocytes. The FDA label warns that resolution was not confirmed in all cases after stopping. Rotating injection sites and limiting use to eight or fewer doses per month appears to minimize this risk based on community experience. Drug interactions matter here. Bremelanotide significantly reduces systemic exposure of oral naltrexone, a pharmacokinetic interaction serious enough that the FDA lists it as a contraindication. Patients on naltrexone for alcohol or opioid use disorder must avoid PT-141. Bremelanotide may also slow gastric emptying, delaying absorption of other oral medications. Pregnancy is a contraindication. Known hypersensitivity to bremelanotide or excipients is a contraindication. Moderate to severe hepatic impairment increases drug exposure and should prompt dose adjustment or avoidance. When to stop: discontinue if blood pressure elevation persists beyond 12 hours, if focal hyperpigmentation appears, if nausea remains unmanageable after multiple doses with anti-emetic support, or if no improvement is seen after 8 weeks of use (per FDA label guidance).
Verify PT-141 dosing and safety with a second opinion
FDA-approved brand (Vyleesi autoinjector) is verified and the safest option. However, the majority of community use involves research-grade vials from unregulated vendors where purity, sequence fidelity, and contamination cannot be confirmed without independent testing.
| Test | When | Target |
|---|---|---|
| Blood pressure | Baseline before first dose; within 12 hours of each dose if cardiovascular history present | Systolic rise <30 mmHg from baseline; avoid use if uncontrolled hypertension |
| Skin inspection: injection sites | After each use; monthly overall check | — |
| Efficacy self-assessment | After 8 weeks of use (per FDA discontinuation guidance) | — |
Bremelanotide causes transient BP elevation documented in FDA Phase 3 trials; resolves within 12 hours
Focal hyperpigmentation from MC1R activation reported in 1% of Phase 3 patients; may be permanent in some cases
FDA label recommends stopping after 8 weeks if no meaningful improvement; on-demand use requires periodic reassessment
Onset of effects within 45-60 minutes of SC injection. Nausea is most common on first use. Flushing and warmth may occur as MC4R activation begins.
Nausea typically decreases with repeated use. Patients learn optimal timing relative to activity. Effects last approximately 6-12 hours after dosing.
Side effect profile stabilizes. Patients establish personal effective dose within the 0.5-1.75mg range. On-demand pattern becomes routine.
Consistent on-demand use as needed, up to 8 doses per month. No tachyphylaxis observed in clinical trials lasting 24 weeks. Blood pressure should be monitored periodically.
0 to 60 minutes (first dose): Peak plasma concentration hits around the one-hour mark. MC4R activation starts driving central arousal within 45 to 60 minutes. Nausea often arrives before the desired effects do, affecting 40% of users on that first injection. Flushing, warmth, and tingling are common early signs. Blood pressure may rise transiently. 1 to 6 hours (active window): This is the peak effect window. Most users report strongest desire and arousal between one and four hours post-injection. The half-life is 2.7 hours, but receptor occupancy keeps functional effects going for 6 to 12 hours depending on the individual. Nausea typically fades by the two to three hour mark. Flushing may stick around longer. 6 to 12 hours (resolution): Blood pressure normalizes within 12 hours per FDA label data. Most users feel back to baseline by this point. Some report mild residual headache or fatigue. No hangover effect is typical. Doses 2 through 8 (first month): Nausea drops significantly after the first two to four doses for most people. Personal effective dose becomes clear, usually landing between 1,000 and 1,750 mcg. No tachyphylaxis was observed at 1.75 mg over 24 weeks in Phase 3 trials; a 52-week extension (PMC6819023) confirmed sustained efficacy. Month 2 onward (ongoing use): Long-term safety was confirmed through 76 total weeks of clinical follow-up with no new safety signals. Most users settle into an on-demand pattern, reserving PT-141 for specific occasions due to nausea management overhead and cost. Focal hyperpigmentation risk increases with use frequency; rotating injection sites is important.
Tmax ~1 hour. MC4R activation begins driving central arousal. Nausea onset typically within 1 hour (40% incidence). BP may transiently rise.
Variable first-dose experience. Many users report strong nausea before effects kick in. Some feel warmth, flushing, and tingling. Sexual arousal and desire often noticeable by 45–60 min.
Maximum plasma concentration ~1 hour. Effects expected within this window. Half-life 2.7 hours. Functional duration extends 6–12 hours based on receptor occupancy.
Most users report peak desire and arousal effects between 1–4 hours. Effect duration varies widely: some report 6–8 hours, others 12+ hours.
BP elevation resolves within 12 hours per FDA label. Plasma concentrations approaching elimination phase.
Most users feel back to normal by 12 hours. Some report residual mild fatigue or headache. No hangover effect typically reported.
No tachyphylaxis observed at 1.75 mg over 24-week Phase 3 trials. Continued efficacy sustained through 52-week extension (PMC6819023).
Most users report nausea decreases significantly after 2–4 doses. Personal effective dose becomes clear. Many stabilize at 1,000–1,750 mcg.
Long-term safety confirmed through 76 weeks total (24-week trial + 52-week extension) with no new safety signals. Max 8 doses/month per FDA.
Consistent on-demand use. Most users reserve for high-priority occasions due to nausea management overhead and cost. Some note continued mild improvement in baseline desire over time.
Source: FDA Prescribing Information (Vyleesi), Section 12.3
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Bremelanotide received FDA approval in June 2019 under the brand name Vyleesi (NDA 210557) for the treatment of acquired, generalized hypoactive sexual desire disorder in premenopausal women. It is manufactured by Cosette Pharmaceuticals as a prefilled single-dose autoinjector delivering 1.75 mg subcutaneously. The FDA label explicitly states bremelanotide is "not indicated in men or in postmenopausal women." Off-label prescribing by licensed physicians is legal but carries reduced clinical safety data compared to the approved population. Research-grade bremelanotide sold as lyophilized powder is available from peptide suppliers for research purposes. These products are not FDA-approved for human use. Quality varies; certificates of analysis with HPLC purity data and mass spectrometry confirmation (MW 1,025.2 Da) should be required from any supplier. PT-141 does not appear on the World Anti-Doping Agency (WADA) prohibited list. Peptide Schedule provides information for research and educational purposes only. This content does not constitute medical advice, and readers should consult a licensed healthcare provider before using any peptide.
Peptide Schedule Research TeamReviewed Apr 202610 Citations
