PT-141

Typical use cases

Dosing guidelines

Titration

Typically not titrated; used on-demand at a fixed reported dose. Some community protocols describe starting with a fraction of a dose to gauge nausea tolerance, but this is not part of the approved regimen.

Reconstitution

The FDA-approved Vyleesi product is a pre-filled single-dose autoinjector and requires no reconstitution. Research/lyophilized powder forms are commonly reconstituted with bacteriostatic water (e.g., 1-2 mL per vial) and gently swirled, not shaken.

Injection sites

Subcutaneous injection, commonly into the abdomen or thigh.

Storage & handling

Vyleesi autoinjector: store at room temperature, around 20-25°C (68-77°F); do not freeze; keep in the original case and protect from light. Reconstituted research solution is generally kept refrigerated (2-8°C); unreconstituted lyophilized powder is stable refrigerated or frozen and away from light.

Side effects

• Nausea Moderate · Common
• Flushing Mild · Common
• Headache Mild · Common
• Transient increase in blood pressure with decreased heart rate Moderate · Common
• Focal hyperpigmentation (darkening of skin/gums, may be permanent) Moderate · Uncommon
• Injection-site reactions Mild · Common

Research summary

Bremelanotide is a synthetic cyclic heptapeptide and analog of alpha-MSH that non-selectively activates melanocortin receptors, with its desire-modulating effects attributed mainly to MC4R (and to a lesser extent MC3R) agonism in hypothalamic and limbic regions (paraventricular nucleus, medial preoptic area, nucleus accumbens), where it is thought to stimulate dopamine release. Unlike PDE5 inhibitors, its mechanism is centrally mediated rather than vascular. The strongest human evidence comes from the two identical phase 3 RECONNECT trials (n=1,267 premenopausal women with acquired, generalized hypoactive sexual desire disorder), which showed statistically significant but modest improvements in desire and reductions in associated distress versus placebo over 24 weeks, with benefits sustained in a 52-week open-label extension and no new safety signals. On the strength of these trials the FDA approved Vyleesi (1.75 mg subcutaneous, on-demand) in 2019. Limitations include modest effect sizes, high placebo response, a study population that was predominantly white and U.S.-based, and high rates of nausea contributing to discontinuation. Robust controlled human data outside the female premenopausal HSDD indication (e.g., male sexual dysfunction, recreational community use) are limited and largely derived from earlier or smaller studies. Reported community/research use of PT-141 frequently differs in route and dose from the approved product, and such use is not supported by the pivotal trial evidence.

Key references

• https://pubmed.ncbi.nlm.nih.gov/31599840/
• https://pmc.ncbi.nlm.nih.gov/articles/PMC8788464/
• https://www.ncbi.nlm.nih.gov/books/NBK573221/
• https://pubmed.ncbi.nlm.nih.gov/31599847/
• https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/210557s000lbl.pdf

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