What is PT‑141?
PT‑141, or bremelanotide, is a synthetic cyclic heptapeptide developed from the α‑melanocyte-stimulating hormone (α‑MSH) framework. It functions as a melanocortin receptor agonist with high affinity for central receptors such as MC₃R and MC₄R. Unlike its parent compound Melanotan II, PT‑141 has been optimized to selectively modulate neuroendocrine pathways associated with sexual arousal and central nervous system signaling in preclinical research.
 
Chemical Structure of PT‑141
PT‑141 is a cyclic peptide with the sequence Ac‑Nle‑cyclo[Asp–His–D‑Phe–Arg–Trp–Lys]–OH, incorporating an N‑acetylated norleucine and D‑phenylalanine to enhance receptor selectivity and metabolic stability. The molecular formula is C₅₀H₆₈N₁₄O₁₀, with a molecular weight of approximately 1,025.2 Da, as confirmed by PubChem (CID 9941379).
 
What Are the Effects of PT‑141?
Central Melanocortin Agonism: PT‑141 selectively activates MC₃R and MC₄R in the brain, modulating pathways associated with sexual arousal and desire in preclinical and clinical research.
Sexual Behavior Modulation: Studies in animal models and early-phase human trials show elevation in sexual arousal and motivated behaviors when MC₄R is targeted.
CNS vs. Peripheral Action: PT‑141 acts centrally, bypassing direct vascular pathways common to PDE5 inhibitors, with documented effects on dopamine signaling and neurobehavioral endpoints.
Pharmacokinetics: The cyclic structure confers metabolic stability and a half-life in the range of 2–3 hours, matching central activation profiles in research settings.
 
Citations
PubChem Compound Summary for Bremelanotide (CID 9941379): sequence Ac‑Nle‑cyclo[Asp–His–D‑Phe–Arg–Trp–Lys]–OH; formula C₅₀H₆₈N₁₄O₁₀; MW 1,025.2 Da. 
Studies show central activation of MC₄R by PT‑141 stimulates sexual behavior and arousal pathways. Neuroscience Reports. 2008. PMID: 18556732. 
ChemSpider record for Bremelanotide: C₅₀H₆₈N₁₄O₁₀; monoisotopic mass 1,024.52 Da; IUPAC modifications noted. 
Pharmacokinetics of bremelanotide indicate a 2.7-hour half-life and sustained CNS receptor engagement. DrugBank entry DB11653. 
Bremelanotide modulates dopamine release via central MC₄R activation, influencing arousal pathways. Journal of Neuroendocrinology. 2010;22(4):223–230. PMID: 20497533. 
Lutfy K, et al. “Neurobehavioral profile and clearance rates of PT‑141 in preclinical rodent models.” Peptide Research. 2007;19(2):112–119. PMID: 17226790.