PT-141

What it is

PT-141 is a cyclic peptide derived from Melanotan 2. It differs only at its end group, which changes how it behaves in the body. It was developed by Palatin Technologies as bremelanotide.

How it works

It activates melanocortin receptors in the brain, mainly MC4, in pathways involved in sexual motivation. It acts on the nervous system rather than on blood flow.

What the research shows

• The RECONNECT phase 3 trials found modest improvements in desire and less distress compared with placebo (Kingsberg et al., Obstetrics and Gynecology, 2019).
• Nausea was the most common side effect; temporary rises in blood pressure and skin darkening with repeated use were also reported.

Regulatory status

FDA-approved in 2019 as Vyleesi, an autoinjector for premenopausal women with acquired, generalized hypoactive sexual desire disorder. Requires a prescription.

Storage and handling

Lyophilized (freeze-dried) powder is most stable sealed, dry and protected from light. Laboratory practice is to keep unopened vials frozen at about -20 °C for long-term storage, or refrigerated at 2 to 8 °C for shorter periods. After reconstitution, keep the solution refrigerated at 2 to 8 °C, avoid repeated freeze-thaw cycles and use aseptic technique for every draw. Formal stability data in solution has not been published for most research peptides, so follow the supplier's label and certificate of analysis.

Reconstitution math

To work out concentration, volume and U-100 syringe units for any vial size, use the reconstitution calculator with PT-141 selected. Always confirm the vial content against the label and the batch's certificate of analysis.

Key references

• Kingsberg SA et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials. Obstet Gynecol. 2019.
• Search PubMed for PT-141 studies
• Official drug labeling on DailyMed

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