Bremelanotide is one of the few research peptides in this space that carries a full FDA approval. In June 2019 it was cleared under the brand name Vyleesi to treat acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women, per the FDA's approval announcement. It is sold as a single-use subcutaneous autoinjector, not a vial of research powder.
In peptide-buyer circles it is far better known by its development code, PT-141. Other names you'll see include PT 141, the CAS number 189691-06-3, and the older lab designation tied to its parent compound, melanotan II.
What it is
Bremelanotide is a synthetic cyclic heptapeptide derived from alpha-melanocyte-stimulating hormone (alpha-MSH). It belongs to the melanocortin agonist family. It was developed by Palatin Technologies as a structural relative of melanotan II, modified to keep the central effects while reducing the skin-tanning activity that melanotan is known for.
Its molecular formula is C50H68N14O10, per PubChem.
Mechanism
Unlike the PDE5 inhibitors used for erectile dysfunction (sildenafil and its relatives), bremelanotide does not work on blood flow. It acts centrally, as a non-selective agonist at melanocortin receptors, with activity at the MC4 receptor in the brain thought to drive the effect on sexual desire. That central pathway is the reason its approved use is about desire and distress rather than mechanical arousal.
What the research shows
The approval rested on two identical Phase 3 trials, known together as RECONNECT (Studies 301 and 302). These were randomized, double-blind, placebo-controlled, and ran for 24 weeks. Roughly 1,267 premenopausal women with HSDD were randomized, with about 1,247 in the safety analysis. Participants self-administered 1.75 mg subcutaneously, as needed, ahead of anticipated activity.
The co-primary endpoints were change in the Female Sexual Function Index desire-domain score and a distress item from the Female Sexual Distress Scale. Both trials hit statistical significance on both endpoints. The improvements were real but modest in absolute terms: desire-score gains over placebo of about 0.30 (Study 301) and 0.42 (Study 302), with corresponding reductions in distress. The FDA noted that about 25% of treated women saw a meaningful rise in their desire score versus about 17% on placebo. The full results were published by Kingsberg and colleagues in *Obstetrics & Gynecology* (2019).
The most common side effects in the trials were nausea, flushing, and headache, each reported in 10% or more of treated women. Most were mild to moderate.
A few safety points from the prescribing information are worth knowing:
- It causes a transient rise in blood pressure and a small drop in heart rate, peaking a few hours after a dose and usually settling within 12 hours. Because of this it is contraindicated in people with uncontrolled hypertension or known cardiovascular disease.
- Dosing is capped: no more than one dose in 24 hours, and no more than eight in a month. More frequent use raises the risk of focal hyperpigmentation (darkening of skin, gums, face, or breasts), reported in about 1% of trial participants and not always reversible after stopping.
Research in men, mainly for erectile dysfunction, reached earlier-phase clinical testing, but the approved indication is the female HSDD population described above.
Regulatory and quality notes
The approved product is the Vyleesi autoinjector. Bremelanotide sold as a loose "PT-141" powder is a different matter: that material is research-use-only and not approved for human consumption, and it sits outside the manufacturing and labeling controls that apply to the prescription drug.
That gap is where independent testing matters. For research-grade peptide powders, the practical questions a buyer can actually check are identity and purity, ideally backed by a batch-specific certificate of analysis (COA) with HPLC and mass-spec data, plus whatever third-party rater coverage exists for a given vendor. None of that turns a research chemical into an approved medicine, but it speaks to whether the vial contains what the label claims.
Nothing here is medical or dosing advice. Bremelanotide is a prescription drug in its approved form; its research-chemical form is not approved for human use. Figures and claims above are attributed to the sources linked.