PT-141

PT-141, the research-phase name for bremelanotide, is a synthetic cyclic heptapeptide structurally derived from melanotan II, which is itself a cyclic analogue of endogenous alpha-melanocyte-stimulating hormone (alpha-MSH). It functions as a non-selective agonist at melanocortin receptor subtypes, engaging primarily MC1R, MC3R, and MC4R.

The therapeutic action is attributed principally to MC4R activation within the hypothalamus and limbic system. Unlike phosphodiesterase type-5 inhibitors, which act peripherally on vascular smooth muscle to facilitate erection, bremelanotide acts centrally to modulate the neural circuitry governing sexual desire and motivation. MC4R-mediated signaling engages dopaminergic pathways associated with reward processing and anticipatory behavior, and this central mechanism is believed to underlie the improvements in sexual desire observed in clinical trials. The precise downstream signaling cascade has not been fully characterized; the FDA prescribing information describes the mechanism as not completely understood.

MC1R activation, though secondary to the principal therapeutic effect, stimulates melanocytes to increase melanin synthesis and accounts for the focal skin hyperpigmentation observed in a minority of users with repeated dosing.

• Subcutaneous bioavailability: approximately 100% • Time to peak plasma concentration: 0.5–1.0 hours post-injection • Plasma half-life: approximately 2.7 hours (range 1.9–4.0) • Plasma protein binding: approximately 21% • Elimination: approximately 64.8% renal, 22.8% fecal • Metabolism: hydrolysis of peptide amide bonds and cellular peptidases

The pivotal clinical program comprised two identical Phase 3 randomized, double-blind, placebo-controlled multicenter trials designated RECONNECT Studies 301 and 302, enrolling a total of 1,267 premenopausal women with acquired, generalized HSDD randomized 1:1 to subcutaneous bremelanotide 1.75 mg or placebo as needed over 24 weeks. The safety population was 1,247; the modified intent-to-treat (mITT) efficacy population was 1,202 participants, with a mean age of 39 years (Kingsberg et al., 2019; PMID 31599840).

Both co-primary endpoints were met in the integrated analysis. Mean change in the Female Sexual Function Index desire domain (FSFI-D) score from baseline to end of study favored bremelanotide over placebo by 0.35 points (p<0.001). Mean reduction in sexual distress as measured by FSDS-DAO Item 13 favored bremelanotide by 0.33 points (p<0.001). A published review of RECONNECT data reported a clinical responder rate of 58% for bremelanotide versus 36% for placebo. A prior Phase 2b dose-finding trial found that all seven prespecified efficacy endpoints at the 1.75 mg dose reached statistical significance versus placebo (p ≤ 0.03), including an increase in satisfying sexual events of +0.7 versus +0.2 per month (p=0.018) and improvement in total FSFI score of +3.6 versus +1.9 (p=0.002).

Prespecified subgroup analyses of the RECONNECT data (PMID 35230162) confirmed that improvements in desire and distress were consistent across age, BMI, bioavailable testosterone quartile, hormonal contraceptive use, and HSDD duration subgroups, with few exceptions. A nested exit survey and telephone interview study (n=242 completing surveys, n=80 telephone interviews; PMID 33538638) corroborated primary findings, with participants in the active arm reporting increased feelings of sexual desire, physical arousal, and quality of sexual activities.

Bremelanotide received FDA approval in June 2019 as Vyleesi, indicated for acquired, generalized HSDD in premenopausal women. It is not indicated for postmenopausal women or men. Clinical development in men for erectile dysfunction reached Phase 2 but was not advanced to Phase 3 controlled trials; off-label use in men therefore lacks Phase 3 trial support.

Typical dosage: 1.75 mg (as needed).

The FDA-approved dosage of bremelanotide (Vyleesi) is 1.75 mg administered as a single subcutaneous injection in the abdomen or thigh via a prefilled disposable autoinjector pen, at least 45 minutes before anticipated sexual activity. No more than one dose is permitted within any 24-hour period, and total use is limited to a maximum of eight doses per month. No dose adjustment is specified based on age alone within the approved premenopausal indication.

Compounded formulations marketed under the PT-141 designation are dispensed by 503A compounding pharmacies and typically take the form of lyophilized powder in 5 mg or 10 mg vials reconstituted for subcutaneous injection with bacteriostatic water. Prescribers using compounded preparations sometimes initiate dosing at 0.5 to 1 mg subcutaneously and titrate upward based on response and tolerability. These titration protocols are derived from clinical experience and are not validated in controlled trials; they do not carry regulatory endorsement and represent off-label clinical practice.

Off-label use in men is reported in compounding-based clinical settings, with subcutaneous doses ranging from 1 to 2 mg; this is not supported by Phase 3 evidence.

This information is provided for educational purposes only and does not constitute medical advice. Bremelanotide is a prescription medication; appropriate use requires evaluation and supervision by a licensed healthcare provider.

Lyophilized (before reconstitution)

Store at room temperature per the FDA label (approximately 20–25°C). Vyleesi is supplied as a pre-filled single-dose autoinjector and is not refrigerated.

Reconstituted

Vyleesi is single-use — administer promptly and discard the autoinjector after use. No in-use storage period applies.

For general storage chemistry (bacteriostatic vs sterile water, freeze-thaw, BUD framework), see Storage & handling.

Last reviewed: July 1, 2026

The pharmacologically best-supported combination pairs bremelanotide with a PDE5 inhibitor (sildenafil or tadalafil) for men with erectile dysfunction unresponsive to PDE5 inhibitor monotherapy. The mechanistic rationale is complementarity: bremelanotide addresses central sexual desire and arousal via MC4R agonism, while PDE5 inhibitors act peripherally on vascular erectile function. Phase 2 clinical work in men with PDE5-inhibitor-nonresponsive erectile dysfunction suggested potential additive benefit, and Palatin Technologies initiated a formal clinical program evaluating a co-formulated bremelanotide/PDE5 inhibitor product. Phase 3 evidence for this combination does not exist; its clinical use remains off-label.

In compounding-based and integrative medicine practice, PT-141 is sometimes prescribed alongside testosterone therapy in men with documented hypogonadism and low libido, based on the premise that adequate androgen tone may support melanocortin pathway sensitivity. Evidence for this combination in humans is anecdotal and no controlled trial data are available.

Combinations with other peptides or performance compounds circulate in community forums but have no clinical trial support and should be considered speculative.

PT-141 is approved by the U.S. Food and Drug Administration for one or more clinical indications. Refer to the prescribing information for full safety and dosing details.

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Reported side effects: Nausea, flushing, blood pressure changes

In the RECONNECT Phase 3 safety population (n=1,247), the most frequent adverse events were nausea (40.0% bremelanotide vs. 1.3% placebo), flushing (20.3% vs. 0.3%), injection-site reactions (13.2%), and headache (11.3% vs. 1.9%). Nausea typically began approximately one hour after injection, resolved within approximately two hours, and was the cause of discontinuation in 8.1% of participants receiving bremelanotide. Vomiting and restless leg syndrome were also reported at lower frequencies.

Bremelanotide produces a transient, dose-related increase in blood pressure and decrease in heart rate after each injection. Ambulatory monitoring demonstrated mean systolic and diastolic blood pressure increases of approximately 1.9 to 2.8 mmHg, returning to pre-dose levels within 12 to 24 hours. The drug is contraindicated in patients with uncontrolled hypertension or known cardiovascular disease.

Focal hyperpigmentation of the face, gingiva, or breasts was observed in approximately 1% of trial participants, attributable to MC1R-mediated melanocyte stimulation. The discoloration may not fully resolve after discontinuation, particularly in individuals with darker baseline skin tones. Risk increases with use beyond eight doses per month.

Post-marketing surveillance has identified a single case of clinically apparent acute hepatitis with marked serum aminotransferase elevation that resolved following discontinuation; NIH LiverTox assigns bremelanotide a likelihood score of D (possible but rare cause of clinically apparent liver injury). Known drug-drug interactions are minimal. Use during pregnancy or breastfeeding is not recommended. Caution is warranted when co-administered with other vasoactive agents given the blood pressure effect.