What Is PT-141?
PT-141, also known as bremelanotide, is a synthetic cyclic heptapeptide and melanocortin peptide. It is structurally related to α-melanocyte-stimulating hormone (α-MSH) and contains a modified seven-amino-acid sequence with a lactam ring.
The peptide is classified as a melanocortin receptor agonist. Its molecular structure includes N-acetyl-L-norleucine, aspartic acid, histidine, D-phenylalanine, arginine, tryptophan and lysine residues arranged within the cyclic peptide structure.
Research Overview Table
Chemical and Molecular Characteristics
Certificates:
Mechanism of Action Under Investigation
PT-141 (bremelanotide) binds to and activates the melanocortin-4 receptor (MC4R). Structural analysis shows the peptide positioned within the receptor's extracellular binding pocket, with interactions involving residues across the transmembrane region. A calcium ion is located at the ligand–receptor interface and participates in peptide recognition.
MC4R activation by bremelanotide is associated with coupling to the Gs protein and increased intracellular cAMP signaling. Mutational analysis of receptor residues involved in ligand recognition altered the bremelanotide induced cAMP response. These findings define important components of receptor activation, although the complete molecular basis of MC4R signaling remains under investigation.
Scientific Research Context
PT-141 (bremelanotide) appears in the scientific literature as a synthetic melanocortin receptor agonist investigated in relation to melanocortin receptor biology and neurobiological signaling. Published work includes receptor pharmacology, animal research and human clinical studies. Therefore, the evidence for PT-141 is not derived primarily from in vitro and preclinical animal models, because controlled human studies are also established in the literature.
PT-141 Biology and Biological Pathways
Primary Biological Function
The melanocortin system has established roles in energy homeostasis, reproduction, sexual function, and neuroendocrine regulation. MC4R is particularly associated with central regulation of energy balance and has also been implicated in sexual behavior and reproductive physiology.
Relevant Metabolic or Signalling Pathways
MC4R is a G protein-coupled receptor associated with Gs-dependent cAMP signaling. Published studies also report MC4R signaling through other G proteins, β-arrestin recruitment and ERK/MAPK pathways. The relative contribution of these pathways can vary with the ligand and receptor variant.
Tissue-Specific Biology
MC4R expression is concentrated in specific neural tissues. In the human hypothalamus, the strongest expression occurs in the paraventricular and supraoptic nuclei. Other studies have identified MC4R in the spinal cord, brainstem, pelvic ganglion and penile nerve fibers and mechanoreceptors.
Experimental Biomarkers
Published studies have used cAMP accumulation to quantify melanocortin receptor signaling. c-Fos immunoreactivity has been used to identify neuronal activation following PT-141 exposure. MC3R and MC4R mRNA expression has also been measured to characterize receptor expression in neural tissues.
Laboratory Investigation Methods
Published melanocortin receptor studies have used receptor-binding assays, cAMP assays, mutational analysis, and structural analysis to examine receptor biology. Studies have also used in situ hybridization and immunohistochemistry to examine receptor expression and localization in neural tissues.
Experimental Models Used in Published Research
Published PT-141 research spans cellular systems and animal models. Each model represents a different level of biological complexity. Their limitations mainly involve the use of engineered cells, species-specific biology, and differences between animal and human physiology.
HEK293 Cell Models
PT-141 studies have used HEK293/HEK293T cells expressing human MC4R. Its limitation is that transfected cells do not reproduce the full cellular and physiological environment of native MC4R-expressing tissues.
Rat Models
Male and female rats have been used as PT-141 research models. A key limitation is the species difference between rats and humans, which makes the findings difficult to apply directly to human biology.
Female Syrian Hamster Models
The female Syrian hamster is one of the animal models represented in the bremelanotide literature. Its limitation is species-specific neurobiology and sexual behavior, which makes direct comparison with human responses difficult.
Nonhuman Primate Models
Nonhuman primates were included in the early PT-141 research. This model has limited representation in the published PT-141 literature, so the available evidence from this model remains limited.
PT-141 Published Scientific Research
Male Sexual Function
Researchers investigated PT-141 in relation to male sexual function and penile erection, including its study in men with erectile dysfunction.
Female Sexual Function
Bremelanotide research examined female sexual function, including sexual desire, arousal, and related sexual-response measures in premenopausal women.
Hypoactive Sexual Desire Disorder
Clinical studies investigated bremelanotide specifically in premenopausal women with hypoactive sexual desire disorder (HSDD).
Pharmacokinetics and Pharmacodynamics
Researchers also investigated PT-141 pharmacokinetics and pharmacodynamics, including drug exposure and physiological responses following administration.
Cardiovascular Responses
Clinical research examined blood pressure and heart-rate responses associated with bremelanotide administration.
Limitations of Current Research
Evidence Is Predominantly Preclinical
Researchers have investigated PT-141 in both preclinical and human clinical studies. Human research includes Phase 2 and Phase 3 trials. So the available evidence extends beyond animal and laboratory research. The clinical literature therefore represents a substantial component of the overall PT-141 evidence base.
Human Clinical Evidence
Human studies have largely examined specific premenopausal populations, particularly women with HSDD. Earlier trials also included women with female sexual arousal disorder. This narrow population limits how well the clinical findings apply to people outside the groups represented in the published trials.
Species Differences
Differences in biological responses between species can limit how findings from preclinical research translate to humans. These differences are particularly relevant when interpreting research involving sexual behavior and reproductive physiology.
Study Design Limitations
The Phase 3 trials used randomized, double-blind and placebo-controlled designs. However, an independent analysis questioned the validity of several outcome measures and found that some reported outcomes were not prespecified. These issues make interpretation of parts of the trial evidence more difficult.
Independent Replication
Independent replication remains limited. The published Phase 3 evidence has mainly been examined through the same RECONNECT development program, while later independent analyses have questioned the validity and reporting of several reported outcomes.
Long-Term Evidence
A 52-week open-label extension followed the 24-week RECONNECT trials. Because all participants received bremelanotide during the extension and the analyses were descriptive. The study does not provide a concurrent placebo-controlled comparison over the full follow-up period.
Analytical Documentation
HPLC separates peptide components and can assess chromatographic purity and related substances. LC-MS adds molecular-mass information and supports confirmation of compound identity. These methods provide complementary analytical information rather than answering the same question.
NMR can provide additional structural information when a more detailed characterization is appropriate. Its use depends on the compound and the analytical purpose.
A Certificate of Analysis (CoA) records the analytical results associated with a specific material or lot. Reviewing this documentation helps establish what was tested, which methods were used, and what the reported results represent. Analytical verification is important in laboratory research because well-characterized materials support consistent interpretation and reproducibility between experiments.
Analytical documentation verifies product identity and quality, not biological performance.
Storage and Laboratory Handling
Keep PT-141 at 2–8°C as stated on the product certificate. Qualified laboratory personnel should handle the material under appropriate laboratory conditions. Keep the container closed when the material is not in use.
Use clean handling practices to prevent contamination. Limit unnecessary exposure during laboratory work and return the material to the specified storage conditions after handling.
Why Researchers Choose Direct SARMs?
Direct SARMs is an established supplier of research peptides. We are committed to product quality, reliable service, and helpful customer support.
Our European-made products undergo rigorous purity testing, with clear product information provided for each research material. We also aim to provide dependable shipping and a smooth ordering experience.
Our support team is available to assist with orders, shipping, payments, and general questions. At Direct SARMs, we aim to make the research supply process simple, clear, and reliable.
Frequently asked questions
Why choose us?
Direct SARMs Slovenia is an established supplier of research peptides. We are committed to product quality, reliable service, and helpful customer support.
Our European-made products undergo rigorous purity testing, with clear product information provided for each research material. We also aim to provide dependable shipping and a smooth ordering experience.
Our support team is available to assist with orders, shipping, payments, and general questions. At Direct SARMs Slovenia, we aim to make the research supply process simple, clear, and reliable.