PT-141 (Bremelanotide)

PT-141 (bremelanotide) is a melanocortin receptor agonist studied for low sexual desire. It is US-approved as Vyleesi for HSDD in premenopausal women and is prescription-only and compounded in Australia.

What it is

PT-141, known generically as bremelanotide, is a synthetic peptide investigated for sexual dysfunction, particularly low sexual desire. Unlike erectile-dysfunction medicines such as sildenafil, which act on blood flow, PT-141 acts on the brain's desire pathways. In the United States it is approved and marketed as Vyleesi, a self-administered injection.

How it works

PT-141 is a melanocortin receptor agonist. It activates melanocortin receptors (chiefly MC4R) in regions of the brain such as the hypothalamus that are involved in sexual arousal and desire. By acting centrally rather than on the vascular system, it is thought to influence the desire component of sexual response. The branded product is given as a subcutaneous injection before anticipated activity.

What the evidence says

The strongest evidence is in premenopausal women with HSDD (hypoactive sexual desire disorder). Two Phase 3 trials (the RECONNECT studies) enrolled over 1,200 premenopausal women; a 1.75 mg subcutaneous dose produced statistically significant improvements in sexual desire and reductions in related distress versus placebo, supporting US FDA approval in 2019. Important limits: the improvements, while statistically significant, were modest on average; and there is no Phase 3 evidence supporting PT-141 in men, in postmenopausal women, or via nasal sprays.

Legal & regulatory status in Australia

Bremelanotide is Schedule 4 (Prescription Only) in Australia. The branded Vyleesi product is not on the ARTG and is not approved by the TGA. Where prescribed, PT-141 is typically supplied as a compounded product by a compounding pharmacy with a valid prescription — compounding is not the same as TGA product approval. Buying bremelanotide without a prescription from overseas "research chemical" suppliers falls outside the lawful pathway and carries legal and safety risks.

Risks & considerations

Commonly reported side effects include nausea (which can be significant), flushing, headache and injection-site reactions. It can cause transient increases in blood pressure and decreases in heart rate, so it is generally avoided in people with uncontrolled high blood pressure or cardiovascular disease. Repeated dosing has been associated with skin darkening (hyperpigmentation) in some people. It was studied for limited use, not daily. Compounded products vary in quality.

What to ask a doctor

• Is my low desire likely to respond to this, and have other contributing factors (relationship, mood, medications, hormones) been assessed first?
• Do my blood pressure or heart health make this unsafe?
• What dose, frequency and side-effect profile apply, and what are the signs I should stop?
• Since this is compounded and not TGA-approved, what quality assurances apply to the product?

FAQ

Q: Is PT-141 approved in Australia? A: No. It is Schedule 4 (prescription only) and not on the ARTG. The US-approved product Vyleesi is not registered here; in Australia it is accessed as a compounded medicine on prescription. Q: Does PT-141 work like Viagra? A: No. Viagra-type medicines act on blood flow, whereas PT-141 acts centrally on brain pathways linked to sexual desire. Q: Is there good evidence it works in men? A: The Phase 3 evidence is in premenopausal women with HSDD. There is no Phase 3 evidence in men, so any such use is not supported by confirmatory trials.