Mechanism Visualization

Neurobiological Pathways

Interactive exploration of PT-141's mechanism of action through the melanocortin receptor system and central nervous system pathways.

Mechanism · Section 01

Interactive Mechanism Preview

LIVE REFERENCE

Receptor

MC4R Activation

Hypothalamus

PT-141 primarily engages melanocortin signaling through MC4R in the hypothalamus, initiating central arousal-related pathways.

Select any node to inspect its pharmacological role

Hypothalamic Activation Pathway

PT-141 crosses the blood-brain barrier and activates melanocortin receptors in the hypothalamus, specifically within the medial preoptic area and paraventricular nucleus.

Melanocortin Receptor Activation

Bremelanotide binds to MC3R and MC4R G-protein coupled receptors, initiating intracellular cAMP signaling cascades that modulate downstream neuroendocrine responses.

Central Nervous System Pathways

Signal propagation from hypothalamic nuclei through limbic circuitry engages dopaminergic, oxytocinergic, and noradrenergic pathways mediating the physiological response.

Signal Transduction Cascade

Ligand Binding

PT-141 binds to MC4R in the paraventricular nucleus of the hypothalamus.

G-Protein Activation

Receptor activation triggers Gαs subunit dissociation, stimulating adenylyl cyclase.

cAMP Cascade

Intracellular cAMP levels increase, activating protein kinase A (PKA) signaling.

Neurotransmitter Release

PKA modulates ion channels, triggering dopamine and oxytocin release in the limbic system.

Descending Signal

Neural signals propagate through spinal autonomic pathways to peripheral target tissues.

Pharmacokinetic Profile

Chemical Classification

Cyclic Lactam Heptapeptide

Synthetic analog of α-melanocyte-stimulating hormone (α-MSH)

Molecular Formula

C₅₀H₆₈N₁₄O₁₀

Molecular weight: 1025.18 g/mol

Primary Targets

MC3R / MC4R

Melanocortin-3 and Melanocortin-4 receptors (G-protein coupled)

Route of Action

Central Nervous System

Hypothalamic activation → limbic pathway engagement

Half-Life

~2.7 hours

Peak plasma concentration: ~1 hour post-administration

Bioavailability

~100% (SC)

Subcutaneous administration yields near-complete bioavailability

Selected References

Molinoff PB, et al. PT-141: A melanocortin agonist for the treatment of sexual dysfunction. Ann N Y Acad Sci. 2003;994:96-102.

Kingsberg SA, et al. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder. Obstet Gynecol. 2019;134(5):899-908.

Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides. 2006;27(4):921-930.

Pfaus JG. Pathways of sexual desire. J Sex Med. 2009;6(6):1506-1533.