PT-141 and bremelanotide: the research behind an approved medicine

The human evidence base is unusually strong for a peptide of this kind. Two randomized phase 3 trials published in 2019 examined bremelanotide in premenopausal women with hypoactive sexual desire disorder, abbreviated HSDD.

What was measured was self-reported desire and how distressing the low desire felt, using questionnaires over several months. The improvements were statistically significant compared with placebo but modest in size.

Nausea was a common side effect and led some participants to discontinue. The trials also reported temporary increases in blood pressure and decreases in pulse after dosing. The results concern a finished drug product in a defined patient group, not a research preparation and not healthy people in general.

PT-141 is a peptide that activates melanocortin receptors. These are receptors in the nervous system that are involved in, among other things, sexual desire, appetite and pigmentation.

The substance works through the central nervous system rather than through the blood vessels, which sets it apart from drugs that affect blood flow.

Two randomized phase 3 trials published in 2019 in Obstetrics and Gynecology examined bremelanotide in premenopausal women with hypoactive sexual desire disorder, often abbreviated HSDD.

The trials reported statistically significant improvements in measures of desire and in the level of experienced distress compared with placebo. At the same time, the improvements were modest in size, which is an important part of the result.

Nausea was a common side effect. The trials also reported temporary changes in blood pressure and pulse after dosing.

The FDA approved bremelanotide under the name Vyleesi in June 2019 for premenopausal women with acquired, generalized HSDD. This is shown in the FDA's approval documents and in the approved prescribing information.

The approval concerns a specific diagnosis, a specific patient group and a finished drug product with a defined manufacturing process. It says nothing about other uses and nothing about research preparations.

The mechanism is built on activation of melanocortin receptors in the brain, above all the MC4 receptor, which is linked to signaling pathways for sexual desire.

The fact that the substance acts centrally also explains why side effects such as nausea and blood pressure changes occur. These are systemic effects, not local ones.

An approval is no guarantee of benefit for everyone. It means the regulator judged that the benefits outweigh the risks for a defined group.

Bremelanotide has been tested in two randomized phase 3 trials and approved by the FDA for a narrowly defined diagnosis.

The effect was modest and side effects such as nausea were common. The results concern a finished drug product in a defined patient group.