PT-141 (Bremelanotide) Dosage Guide: Timing, Protocol & Side Effects

PT-141 (also called bremelanotide, peptide 141, or pt141) is a synthetic cyclic peptide that activates two melanocortin receptors in the brain, MC3R and MC4R. It is the active ingredient in Vyleesi, an FDA-approved injection for premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD). It is not an erection drug like sildenafil or tadalafil. It works through the central nervous system, not by changing blood flow.

This page is an educational protocol reference. The dosing information here describes the FDA-approved Vyleesi label and published clinical trial protocols. It is not a recommendation for personal use and does not cover every clinical scenario.

PT-141 is studied in two main administration formats: the FDA-approved subcutaneous injection (Vyleesi) and an investigational intranasal route used in earlier Phase 2 work. Dosing is meaningfully different between the two routes because of how each is absorbed.

Receptor downregulation has been raised as a theoretical concern with very frequent melanocortin agonist exposure, which is part of why the Vyleesi label caps monthly use at 8 doses. Long-term safety beyond the 76 weeks studied in Kingsberg 2019 and Simon 2019 has not been formally established.

Reconstitution applies to research-grade lyophilized PT-141 vials. The FDA-approved Vyleesi product is sold as a pre-filled autoinjector and does not require reconstitution. The math below describes what concentration results from a generic 10 mg research vial with different bacteriostatic water volumes.

PT-141 increases sexual desire and arousal by acting on the brain. It is a cyclic heptapeptide that activates two of the five melanocortin receptors, MC3R and MC4R. These receptors are densely expressed in the hypothalamus, especially in the paraventricular nucleus (PVN), which is one of the brain's main control hubs for autonomic and reproductive function.

When MC4R is activated in the PVN, it stimulates downstream oxytocin neurons that project to the spinal cord and influence sexual response. This is a centrally-initiated mechanism. PT-141 does not work by changing penile blood flow the way a PDE5 inhibitor like sildenafil does. That difference is why PT-141 affects desire, while sildenafil affects mechanical erectile function.

PT-141 also has moderate affinity for MC1R (the pigmentation receptor) and negligible activity at MC2R (the cortisol-axis receptor) or MC5R. The MC1R activity is part of why darkening of the skin, gums, or breasts is listed as a possible adverse effect on the Vyleesi label.

Vyleesi is approved only for premenopausal women with acquired, generalized HSDD that is not better explained by a medical or psychiatric condition, relationship distress, or medication side effects. The Vyleesi label states that postmenopausal women and men should not use it, and that it is not approved to enhance sexual performance. There is no FDA-approved PT-141 protocol for any other population.

Women in the RECONNECT Phase 3 program self-administered 1.75 mg bremelanotide on demand and showed significant improvements in desire and reduced distress versus placebo over 24 weeks. The 1.75 mg dose was used regardless of body weight. The label does not advise weight-based dose adjustment. This is not a dosing recommendation.

The Vyleesi label and the Mayo Clinic drug summary state that PT-141 should not be used in people with uncontrolled hypertension or known cardiovascular disease, because of the transient blood pressure rise after dosing. It is also not recommended during pregnancy or while planning pregnancy, and there is no adequate safety data for breastfeeding.

Severe kidney or liver disease may slow clearance. Conditions that delay gastric emptying may worsen with PT-141 because melanocortin agonism slows gastric emptying. Naltrexone is listed as a notable interaction (PT-141 may reduce naltrexone exposure when both are used). PT-141 should not be combined with another melanocortin agonist such as Melanotan II, because the receptors overlap and the safety of combined exposure has not been studied.

Side effect rates below come from the FDA-approved Vyleesi label and from the Phase 3 RECONNECT trial publication (Kingsberg 2019). The most common adverse event was nausea, reported by about 40% of bremelanotide users at the 1.75 mg dose. Most events were mild to moderate, decreased over time with repeat use, and did not lead to discontinuation in most participants.

Intranasal PT-141 sold as a compounded product has not been evaluated in Phase 3 trials. Per-spray delivery varies with device, technique, and nasal congestion, which makes consistent dosing harder. Quality control for any non-FDA-approved peptide product is a separate risk and is one reason the Vyleesi label dose is anchored to a sealed autoinjector formulation.

Vyleesi is dosed at least 45 minutes before sexual activity because clinical trials structured the protocol around that interval. This timing reflects the trial design, not a personal use recommendation.

What to monitor in a research or clinical context: blood pressure (because of the transient rise), nausea severity, and any darkening of the skin, gums, or breasts (especially with frequent use). The Vyleesi label suggests a clinician check-in if the condition has not improved after 8 weeks. Long-term safety beyond the 76-week extension period reported in Simon 2019 has not been formally established.

Direct human evidence for PT-141 is strongest in one population: premenopausal women with HSDD. The two RECONNECT Phase 3 trials (Kingsberg 2019) enrolled approximately 1,200 women across both studies, used 1.75 mg subcutaneous bremelanotide on demand for 24 weeks, and met both co-primary endpoints (improved desire score and reduced distress) at p < 0.001 in the integrated analysis. A 52-week open-label extension (Simon 2019) reported a consistent safety profile through longer use.

What the evidence does not establish: there is no Phase 3 evidence supporting PT-141 use in men, in postmenopausal women, or via the intranasal route for any indication. Use outside the FDA-approved Vyleesi protocol relies on Phase 2 data, label-extrapolation, or community-derived practice. The pharmacology is well-characterized; the human efficacy outside the female HSDD indication is not.

Reconstituted research-grade PT-141 is commonly described as stable for several weeks under refrigeration, though stability depends on the supplier's specific formulation. Do not freeze reconstituted solution. Use a fresh alcohol swab on the stopper before each draw.

If significant chest pain, severe headache, fainting, or signs of an allergic reaction occur, seek qualified medical care. This page does not provide emergency guidance.

As of May 2026, bremelanotide is FDA-approved as Vyleesi for the treatment of acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. The approval was granted by the U.S. FDA on June 21, 2019. There is no FDA approval for any other indication or population.

PT-141 and PDE5 inhibitors address different problems. PT-141 affects the desire/arousal pathway centrally; PDE5 inhibitors affect blood flow peripherally. They are not interchangeable. PT-141 and Melanotan II overlap on the melanocortin receptor family and should not be combined; the safety of dual melanocortin agonism has not been formally studied.

If you are researching adjacent compounds, these PDP protocol pages cover related receptors, mechanisms, or use clusters:

Bremelanotide affects sexual-function pathways and can also affect blood pressure. Monitoring focuses on cardiovascular context, reproductive context, and medication interactions.