PT-141 (Bremelanotide) Research Guide for Canadian Labs

PT-141, also known as Bremelanotide, is a cyclic heptapeptide melanocortin receptor agonist derived from Melanotan II. Unlike its predecessor, PT-141 does not produce significant tanning effects, making it a more selective research tool for studying melanocortin receptor-mediated CNS pathways. PT-141 has been approved by the FDA as Vyleesi® for hypoactive sexual desire disorder (HSDD) in premenopausal women, giving it one of the most advanced clinical development profiles among research peptides.

PT-141 (Bremelanotide) is a cyclic lactam analogue of α-MSH (alpha-melanocyte-stimulating hormone) with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH. It was developed from Melanotan II by removing the C-terminal amide and cyclizing the peptide to improve receptor selectivity and reduce melanogenic activity.

Molecular characteristics:

• Sequence: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH
• Molecular weight: 1025.2 Da
• CAS number: 189691-06-3
• Also known as: Bremelanotide, Vyleesi® (FDA-approved)
• Derived from: Melanotan II (cyclic MSH analogue)

PT-141 acts as an agonist at melanocortin receptors, with primary activity at:

• MC3R (Melanocortin 3 Receptor): Expressed in the hypothalamus and limbic system; involved in energy homeostasis, feeding behaviour, and autonomic regulation
• MC4R (Melanocortin 4 Receptor): Widely expressed in the CNS; the primary receptor mediating PT-141's CNS effects; involved in sexual behaviour, energy balance, and cardiovascular regulation

Unlike Melanotan II, PT-141 has minimal activity at MC1R (the primary melanogenic receptor), which is why it does not produce significant skin tanning at research doses.

PT-141's mechanism is centrally mediated — it acts on hypothalamic and limbic MC4R to modulate downstream dopaminergic and oxytocinergic signalling. This distinguishes it from peripherally-acting compounds and makes it a valuable research tool for studying CNS-mediated physiological responses.

MC4R activation in the mesolimbic system modulates dopamine release in the nucleus accumbens. Research has examined this pathway in the context of reward, motivation, and appetitive behaviour.

PT-141 has been shown to transiently increase blood pressure and heart rate via MC4R-mediated sympathetic activation. This cardiovascular profile has been studied in the context of both its therapeutic applications and as a research tool for autonomic nervous system modulation.

The most extensively studied application of PT-141 is in preclinical models of sexual behaviour. Rodent studies using the unanesthetized rat model have demonstrated dose-dependent increases in sexual motivation and performance parameters following PT-141 administration. The CNS-mediated mechanism (via MC4R) distinguishes this from peripherally-acting compounds.

MC3R and MC4R are both involved in hypothalamic regulation of energy balance. PT-141 has been studied in models of obesity and metabolic dysfunction as a tool for investigating melanocortin pathway contributions to feeding behaviour and energy expenditure.

PT-141's transient pressor effects have been studied as a model for sympathetic activation and cardiovascular regulation. Research has examined the MC4R-mediated pathway in the context of blood pressure regulation and heart rate variability.

Melanocortin receptors, particularly MC3R, are expressed on immune cells and have anti-inflammatory signalling properties. PT-141 has been studied in models of inflammatory conditions for its potential immunomodulatory effects via the melanocortin system.

Emerging preclinical research has examined MC4R agonism in the context of neuroprotection, with studies investigating PT-141 in models of traumatic brain injury and ischemic stroke.

For research specifically targeting MC3R/MC4R-mediated CNS pathways, PT-141 is the preferred compound due to its reduced MC1R activity and improved receptor selectivity.

PT-141 is supplied as a lyophilized powder requiring reconstitution with bacteriostatic water (BAC water).

Suggested reconstitution:

• 10 mg vial + 2 mL BAC water → 5 mg/mL (5,000 mcg/mL)
• 10 mg vial + 5 mL BAC water → 2 mg/mL (2,000 mcg/mL)

Use our Reconstitution Calculator for precise volume calculations. See our General Reconstitution Guide for sterile technique.

PT-141 is stable in solution when stored correctly. Protect from light to prevent photodegradation of the tryptophan residue.

PT-141 10 mg is currently coming soon at Peptide-Labs. We are completing quality verification and third-party CoA testing before release. Join the waitlist to be notified when PT-141 becomes available.

PT-141 is intended solely for in vitro research and preclinical laboratory use. It is not approved for human consumption, veterinary use, or clinical application in Canada outside of its FDA-approved indication (which applies in the US only). All research must be conducted by qualified professionals in compliance with applicable regulations.