PT-141 vs Kisspeptin: How They Differ
PT-141 (bremelanotide) acts on melanocortin receptors in the brain and is studied directly for sexual desire, while kisspeptin is the hormone at the top of the reproductive axis, switching on GnRH and with it LH and testosterone, and it also changes how the brain processes sexual cues. Both have been tested in randomised trials in people with low sexual desire, but through different systems: PT-141 bypasses the hormones, kisspeptin works through them and alongside them. Here is how they compare, and why the Libido Trifecta Spray Stack carries both.
Findings
- PT-141 has the larger record: two phase 3 trials randomised 1,267 premenopausal women with hypoactive sexual desire disorder and found significant gains in desire and falls in distress (2019).
- In a crossover trial of 32 men with hypoactive sexual desire disorder, a kisspeptin infusion changed activity across the brain’s sexual-processing network and raised penile tumescence to sexual stimuli by up to 56% more than placebo (2023).
- In 32 premenopausal women with the same diagnosis, kisspeptin modulated sexual and attraction brain processing on functional MRI (2022).
- Kisspeptin raised LH, FSH and testosterone in men within a 90-minute infusion (2005); PT-141’s action is central and not routed through sex hormones.
What is PT-141?
PT-141 is a cyclic seven-residue analogue of alpha-melanocyte stimulating hormone, an agonist at melanocortin receptors including MC3R and MC4R, which are expressed mainly in the central nervous system. In rats it activated hypothalamic neurons connected to the penis, and in men it produced a rapid, dose-dependent increase in erectile activity (Molinoff et al., Ann N Y Acad Sci, 2003). Its approval review describes high affinity for the MC4 receptor, thought to be the important one for sexual function, giving it the potential to modulate brain pathways involved in sexual response (Dhillon and Keam, Drugs, 2019).
The human trials
The first human studies used a nasal form: intranasal PT-141 produced significant erectile responses in healthy men and men with mild-to-moderate erectile dysfunction, with the first erection at about 30 minutes (Diamond et al., Int J Impot Res, 2004). The phase 3 trials used subcutaneous injection in women. Across two identical 24-week studies of 1,267 premenopausal women with hypoactive sexual desire disorder, bremelanotide significantly increased desire and reduced distress compared with placebo; nausea, flushing and headache were the common side effects (Kingsberg et al., Obstet Gynecol, 2019). Gains held through a 52-week open-label extension (Simon et al., Obstet Gynecol, 2019). The full record is in PT-141 human studies.
What is kisspeptin?
Kisspeptin is the product of the KiSS-1 gene. It was isolated from human placenta in 2001 as a 54-amino-acid amidated peptide and the natural ligand of a then-orphan receptor, now called GPR54 or KISS1R (Ohtaki et al., Nature, 2001). Two years later, two groups showed that people with loss-of-function mutations in GPR54 fail to go through puberty, with hypogonadotropic hypogonadism (de Roux et al., PNAS, 2003; Seminara et al., N Engl J Med, 2003). Kisspeptin acts upstream of GnRH and signals directly to GnRH neurons to control pulsatile GnRH release (Skorupskaite et al., Hum Reprod Update, 2014). We supply kisspeptin-10, the ten-amino-acid form.
Hormones first
A 90-minute infusion of kisspeptin-54 in six men significantly raised LH, FSH and testosterone against saline; its plasma half-life was 27.6 minutes (Dhillo et al., J Clin Endocrinol Metab, 2005). The shorter kisspeptin-10 raised LH and FSH in healthy men after an intravenous bolus, and in women only in the preovulatory phase of the cycle (Jayasena et al., J Clin Endocrinol Metab, 2011). In men with type 2 diabetes and low testosterone, an 11-hour kisspeptin-10 infusion increased LH pulse frequency and raised testosterone from 8.5 to 11.4 nmol/L (George et al., Clin Endocrinol, 2013).
Then the brain
The Imperial College London group then asked whether kisspeptin does more than release hormones. In 29 healthy young men, kisspeptin enhanced limbic brain activity specifically in response to sexual and couple-bonding images, and reduced negative mood (Comninos et al., J Clin Invest, 2017). The same group ran two double-blind crossover trials in people with hypoactive sexual desire disorder, each with a 75-minute infusion of kisspeptin-54. In 32 premenopausal women, kisspeptin modulated sexual and facial-attraction brain processing, with larger hippocampal responses in women reporting more distress about their sexual function (Thurston et al., JAMA Netw Open, 2022). In 32 men, it changed activity across the sexual-processing network, increased penile tumescence to sexual videos by up to 56% more than placebo, and increased happiness about sex (Mills et al., JAMA Netw Open, 2023). Those brain studies used kisspeptin-54 by infusion, not kisspeptin-10.
How do PT-141 and kisspeptin compare side by side?
| Question | PT-141 | Kisspeptin |
|---|---|---|
| What is it? | Synthetic cyclic alpha-MSH analogue | Natural hormone from the KiSS-1 gene |
| Size | Seven residues | 54 amino acids (kisspeptin-54) or 10 (kisspeptin-10) |
| Main research area | Low sexual desire and arousal | Reproductive hormones, puberty, fertility; sexual brain processing |
| Mechanism | Melanocortin receptors, high MC4R affinity | KISS1R (GPR54) on GnRH neurons, then LH, FSH, sex steroids |
| Human evidence | Phase 3 trials, 1,267 women; approved in the US in 2019 | Hormone studies since 2005; crossover trials of 32 women (2022) and 32 men (2023) |
| Forms we supply | 10 mg vial; nasal spray in 10 mg and 20 mg | 10 mg vial; 10 mg nasal spray |
Which one fits which research question?
- Central desire signalling independent of hormones: PT-141. Its trials measured desire and distress directly, and it does not act through LH or testosterone.
- The reproductive axis: kisspeptin, for LH pulses, testosterone, puberty and ovulation research.
- Where hormones and sexual brain processing meet: kisspeptin, the one compound here studied for both.
Can PT-141 and kisspeptin be studied together?
Yes. They act at different receptors through different routes, melanocortin signalling for PT-141 and the kisspeptin-GnRH axis for kisspeptin, so a study can track each one’s contribution separately. That rationale comes from each compound’s own literature; no published human trial has given the two together.
The Libido Trifecta Spray Stack combines the Kisspeptin Nasal Spray, the PT-141 Nasal Spray and the Oxytocin Nasal Spray. The Libido Spray Stack is the two-spray version, PT-141 with oxytocin. How PT-141 compares with oxytocin is covered in PT-141 vs Oxytocin.
How are PT-141 and kisspeptin supplied?
PT-141 comes as a 10 mg lyophilised vial and as a nasal spray in two bottle sizes; kisspeptin as a 10 mg vial and a 10 mg nasal spray. The sprays arrive ready-mixed in a sealed metered pump, 0.175 mL per press. The human PT-141 research includes intranasal studies; the human kisspeptin studies used intravenous or subcutaneous administration. Vials are reconstituted with bacteriostatic water (see the PT-141 reconstitution guide and the peptide calculator). Buying details are in Buy PT-141 in Canada and Buy Kisspeptin in Canada, and every order ships from within Canada.
PT-141 and kisspeptin are supplied for laboratory research use only. The studies above were clinical research using pharmaceutical preparations.
Frequently asked questions
What is the difference between PT-141 and kisspeptin?
PT-141 is a synthetic seven-residue peptide that acts on melanocortin receptors in the brain, studied for sexual desire. Kisspeptin is a natural hormone that drives GnRH release and so LH, FSH and testosterone, and has also been shown to change sexual brain processing.
Is PT-141 or kisspeptin better for libido research?
They answer different questions. PT-141 has phase 3 trials in 1,267 women measuring desire directly. Kisspeptin has smaller crossover trials in 32 women and 32 men measuring brain responses, tumescence and desire, plus its hormonal effects.
Does kisspeptin raise testosterone?
In men, yes: a 90-minute kisspeptin-54 infusion raised LH, FSH and testosterone against saline (2005), and kisspeptin-10 raised LH and testosterone in men with type 2 diabetes and low testosterone (2013). PT-141 does not act through these hormones.
Can PT-141 and kisspeptin be studied together?
Yes. They act through separate receptors and pathways, so each one’s contribution stays distinguishable. The Libido Trifecta Spray Stack combines the PT-141, kisspeptin and oxytocin nasal sprays.
Where can I buy PT-141 and kisspeptin in Canada?
Vistara Labs supplies both as lyophilised vials and ready-mixed nasal sprays, plus the Libido Trifecta Spray Stack, shipped from within Canada by Canada Post Xpresspost.
Product details from vistaralabs.ca, October 2026. Sources: Molinoff PB et al. PT-141: a melanocortin agonist for the treatment of sexual dysfunction. Ann N Y Acad Sci. 2003. PMID 12851303. Dhillon S, Keam SJ. Bremelanotide: first approval. Drugs. 2019. PMID 31429064. Diamond LE et al. Double-blind, placebo-controlled evaluation of intranasal PT-141. Int J Impot Res. 2004. PMID 14963471. Kingsberg SA et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials. Obstet Gynecol. 2019. PMID 31599840. Simon JA et al. Long-term safety and efficacy of bremelanotide for hypoactive sexual desire disorder. Obstet Gynecol. 2019. PMID 31599847. Ohtaki T et al. Metastasis suppressor gene KiSS-1 encodes peptide ligand of a G-protein-coupled receptor. Nature. 2001. PMID 11385580. de Roux N et al. Hypogonadotropic hypogonadism due to loss of function of the KiSS1-derived peptide receptor GPR54. PNAS. 2003. PMID 12944565. Seminara SB et al. The GPR54 gene as a regulator of puberty. N Engl J Med. 2003. PMID 14573733. Skorupskaite K et al. The kisspeptin-GnRH pathway in human reproductive health and disease. Hum Reprod Update. 2014. PMID 24615662. Dhillo WS et al. Kisspeptin-54 stimulates the hypothalamic-pituitary gonadal axis in human males. J Clin Endocrinol Metab. 2005. PMID 16174713. Jayasena CN et al. The effects of kisspeptin-10 on reproductive hormone release show sexual dimorphism in humans. J Clin Endocrinol Metab. 2011. PMID 21976724. George JT et al. Kisspeptin-10 stimulates serum testosterone and LH secretion in men with type 2 diabetes and mild biochemical hypogonadism. Clin Endocrinol. 2013. PMID 23153270. Comninos AN et al. Kisspeptin modulates sexual and emotional brain processing in humans. J Clin Invest. 2017. PMID 28112678. Thurston L et al. Effects of kisspeptin administration in women with hypoactive sexual desire disorder: a randomized clinical trial. JAMA Netw Open. 2022. PMID 36287566. Mills EG et al. Effects of kisspeptin on sexual brain processing and penile tumescence in men with hypoactive sexual desire disorder: a randomized clinical trial. JAMA Netw Open. 2023. PMID 36735255.
More on this: Peptides for Libido: What the Research Shows.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
