PT-141 Research: RECONNECT Phase 3 Trials & Melanocortin Pathway Data
A study-by-study look at PT-141 (bremelanotide) — the RECONNECT phase 3 trials that led to regulatory approval, the abandoned intranasal programme and the central melanocortin mechanism.
Mechanism of action
PT-141 (bremelanotide) is a cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (α-MSH), derived from Melanotan II but modified so that the C-terminal amide is replaced by a hydroxyl group — removing most of the tanning activity while retaining the sexual-response effect.
It acts as a non-selective agonist at melanocortin receptors, with the relevant activity at MC3R and MC4R in the central nervous system, principally the hypothalamus.
The mechanism is central, not vascular. Unlike PDE5 inhibitors, which act on peripheral smooth muscle and blood flow, PT-141 modulates the neural pathways that generate sexual desire and arousal upstream of the physical response.
MC1R activity accounts for the residual pigmentation effects sometimes reported, and MC4R activity is also associated with the transient blood-pressure and nausea effects seen in the trials.
The studies
PT-141 has one of the most complete clinical records of any research peptide: two identical phase 3 trials, an open-label extension and an earlier discontinued programme that explains why the delivery route changed.
RECONNECT programme
RECONNECT (Studies 301 and 302) — hypoactive sexual desire disorder
To evaluate the efficacy and safety of on-demand subcutaneous bremelanotide 1.75 mg in premenopausal women with acquired, generalised hypoactive sexual desire disorder (HSDD).
1,267 premenopausal women across two identical trials · 24 weeks · randomised, double-blind, placebo-controlled
- Significant
- Improvement in desire score
- Significant
- Reduction in distress score
- Nausea
- Most common adverse event
vs placebo, both trials
vs placebo, both trials
~40%, mostly first dose
- RECONNECT is the pivotal evidence for bremelanotide and led to its regulatory approval for HSDD in premenopausal women in 2019.
- Both co-primary endpoints — sexual desire and associated distress — were met in two independently powered trials.
- Effect sizes were statistically clear but modest in absolute terms; nausea and transient blood-pressure elevation were the dose-limiting tolerability issues.
RECONNECT open-label extension — long-term safety
To characterise the safety and durability of response over an additional 52 weeks of open-label on-demand dosing following the core RECONNECT trials.
Participants continuing from Studies 301 and 302 · 52 weeks open-label
- Maintained
- Durability of response
- None identified
- New safety signals
- Nausea
- Discontinuation driver
principal reason for withdrawal
- The extension provides the longest controlled human exposure data for this melanocortin agonist.
- Response did not diminish with continued on-demand use over a year.
- Transient increases in blood pressure with each dose were consistent and are the reason cardiovascular status is an exclusion criterion in the clinical literature.
Earlier intranasal programme in erectile dysfunction
To evaluate intranasal bremelanotide for erectile dysfunction, including in men who responded poorly to PDE5 inhibitors.
Men with erectile dysfunction · randomised, placebo-controlled intranasal dosing studies
- Improved
- Erectile response
- Observed
- Blood-pressure increases
- Changed
- Route
vs placebo
led to programme halt
to subcutaneous for later development
- The intranasal programme demonstrated central-pathway efficacy in men, independent of the vascular mechanism PDE5 inhibitors use.
- It was discontinued because intranasal dosing produced unacceptable transient blood-pressure elevations, not because it lacked effect.
- This history is why the approved product is subcutaneous and dose-limited, and why the blood-pressure caveat follows PT-141 throughout the literature.
Storage & handling
PT-141 research material is supplied as a lyophilised powder. Store sealed vials refrigerated or frozen, protected from light and moisture.
Reconstitute with bacteriostatic water added slowly down the inner wall of the vial; swirl gently until dissolved — do not shake.
Keep reconstituted solution at 2-8 °C and use within your lab's defined stability window. Avoid repeated freeze-thaw cycles.
All information on this page is provided for laboratory and educational reference only. Peptides Lab SA (PTY) Ltd supplies compounds strictly for in-vitro research use. Nothing here is medical advice, a dosing recommendation, or a claim of human safety or efficacy.