Metabolic

AOD 9604 is a synthetic hexadecapeptide corresponding to amino acids 176–191 of human growth hormone (hGH), with a tyrosine residue substituted at the N-terminus to confer metabolic stability. The "AOD" designation stands for "Anti-Obesity Drug," reflecting its origin as a drug development candidate by Metabolic Pharmaceuticals. The compound was engineered to isolate the lipolytic domain of hGH while eliminating the anabolic and diabetogenic properties associated with the full-length hormone. Development as a pharmaceutical was formally discontinued in 2007 when a Phase IIb trial of 536 subjects failed to demonstrate statistically significant weight loss. Despite this regulatory failure, AOD 9604 has since been reclassified as a nutraceutical ingredient in some jurisdictions and remains widely used in research settings and compounding pharmacy formulations.

Bioglutide (developmental name NA-931) is a proprietary oral quad-agonist peptide developed by Biomed Industries targeting four receptors simultaneously: insulin-like growth factor-1 (IGF-1R), glucagon-like peptide-1 receptor (GLP-1R), glucose-dependent insulinotropic polypeptide receptor (GIPR), and glucagon receptor (GCGR). This simultaneous engagement of four metabolically relevant pathways positions it as a mechanistically novel advance beyond existing dual and triple agonists such as tirzepatide and retatrutide. Bioglutide is notable for its oral bioavailability — a key differentiator in the injectable-dominated GLP-1 landscape — and for Phase 2 data suggesting preservation of lean muscle mass, which is a significant limitation of current GLP-1 therapies. Full peer-reviewed publication of Phase 2 results is pending as of early 2026; available data comes from conference presentations at the American Diabetes Association (ADA) and European Association for the Study of Diabetes (EASD) 2025 meetings. The molecular formula and precise sequence are proprietary and have not been publicly disclosed by Biomed Industries.

Cagrilintide is a long-acting synthetic analogue of human amylin (islet amyloid polypeptide) developed by Novo Nordisk. It is a 37-amino acid acylated peptide engineered for once-weekly subcutaneous administration, contrasting with the native amylin half-life of approximately 13 minutes. Cagrilintide is in Phase 3 clinical development both as a standalone obesity treatment and as a component of CagriSema, a fixed-ratio combination with semaglutide. The combination approach (CagriSema) represents the most advanced amylin + GLP-1 RA strategy in clinical development. By targeting two complementary satiety pathways — amylin signaling through the area postrema and GLP-1 signaling through hypothalamic neurons — the combination has produced weight reductions exceeding 22% in Phase 3 trials, surpassing the efficacy of either component alone and approaching the range of metabolic surgery.

Mazdutide (also designated IBI362 by its developer Innovent Biologics, or LY3305677 under the Eli Lilly licensing code) is a synthetic once-weekly glucagon-like peptide-1 (GLP-1) and glucagon receptor (GCGR) dual agonist. It is a fatty-acid-conjugated peptide designed for subcutaneous weekly dosing, following the pharmacokinetic engineering approach established by semaglutide. Mazdutide is currently in active Phase 2 and Phase 3 clinical development in China and internationally for obesity and type 2 diabetes. The compound received Breakthrough Therapy Designation from the National Medical Products Administration (NMPA) of China for obesity treatment, accelerating its development pathway. Phase 3 trials are underway; no regulatory approval has been granted in any jurisdiction as of 2025.

Melanotan II (MT-II) is a cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (α-MSH) developed at the University of Arizona in the 1990s. It is a non-selective melanocortin receptor agonist that binds MC1R through MC5R, producing a range of physiological effects including skin pigmentation (tanning), sexual arousal, appetite suppression, and lipolysis. Melanotan II is the parent compound from which PT-141 (bremelanotide) was derived. Despite never receiving regulatory approval in any jurisdiction, Melanotan II has been widely available through grey-market suppliers and has been self-administered by a substantial number of individuals seeking tanning effects. This unregulated use has generated both clinical data (through case reports and surveillance) and safety concerns. The peptide's non-selective melanocortin receptor activity produces broader effects than the more targeted PT-141, which was specifically developed to isolate the MC4R-mediated sexual function effects while minimizing MC1R-driven pigmentation.

MOTS-c (Mitochondrial Open Reading Frame of the Twelve S rRNA Type-C) is a 16-amino acid peptide encoded within the mitochondrial genome, discovered in 2015 by Changhan Lee's group at USC. It is the first mitochondrial-derived peptide shown to function as a systemic signaling molecule, challenging the traditional view that mitochondria primarily encode structural and enzymatic components of the electron transport chain. MOTS-c represents a new class of retrograde signals from mitochondria to the nucleus that regulate metabolic homeostasis. MOTS-c circulates in blood and its levels respond to physiological stimuli — exercise increases circulating MOTS-c, while aging and metabolic disease are associated with declining levels. In preclinical models, exogenous MOTS-c administration prevents diet-induced obesity, improves insulin sensitivity, and reverses age-related physical decline. The peptide has generated significant research interest as a potential exercise mimetic and metabolic regulator, though no human clinical trials have been completed.

Pancragen (KEDW, Lys-Glu-Asp-Trp-NH2) is a synthetic tetrapeptide bioregulator developed by Professor Vladimir Khavinson's group at the St. Petersburg Institute of Bioregulation and Gerontology. It is derived from bovine pancreatic tissue and proposed to restore age-related decline in pancreatic islet cell function. Among the Khavinson-class bioregulator tetrapeptides, Pancragen has the strongest human evidence: a small uncontrolled clinical study published in 2011 reported improvements in glucose tolerance and insulin resistance in elderly type 2 diabetics. Note on sequence: some vendor sources incorrectly list Pancragen as a hexapeptide (Lys-Glu-Asp-Pro-Glu-Pro). Published peer-reviewed literature (PMIDs 18642713, 22448364) consistently gives the tetrapeptide sequence KEDW (Lys-Glu-Asp-Trp-NH2).

PEP-CAG is a designation used by certain research peptide vendors. Based on vendor naming conventions in which "PEP" denotes a proprietary peptide formulation and "CAG" likely indicates a cagrilintide-adjacent sequence (cagrilintide is a long-acting amylin analog developed by Novo Nordisk for obesity treatment), PEP-CAG may refer to a research-grade cagrilintide analog or a blend incorporating cagrilintide-related activity. **No published peer-reviewed research exists for PEP-CAG as a named compound.** No molecular formula, sequence, or clinical data has been publicly disclosed by any vendor using this designation. The compound should be treated as a proprietary, unvalidated peptide with no independent scientific literature. This entry is based on best-effort vendor name interpretation. The underlying biology of cagrilintide (amylin receptor agonism for appetite regulation and weight loss) is well-researched in the context of its parent compound, but nothing in that literature can be attributed to PEP-CAG specifically.

PEP-RT is a designation used by certain research peptide vendors. Based on vendor naming conventions in which "PEP" denotes a proprietary peptide formulation and "RT" likely refers to retatrutide (LY3437943), this designation most probably refers to a research-grade retatrutide analog, variant, or impure preparation. **No published peer-reviewed research exists for PEP-RT as a named compound.** No molecular formula, sequence, mechanism, or safety data has been publicly disclosed for this specific vendor designation. It cannot be verified whether PEP-RT is chemically equivalent to, a structural variant of, or merely inspired by the Eli Lilly clinical compound retatrutide.

PEP-SM is a designation used by certain research peptide vendors. Based on vendor naming conventions in which "PEP" denotes a proprietary peptide formulation and "SM" likely refers to semaglutide, this designation most probably refers to a research-grade semaglutide analog or uncharacterized GLP-1 receptor agonist variant. **No published peer-reviewed research exists for PEP-SM as a named compound.** No molecular formula, sequence, mechanism, or safety data has been publicly disclosed for this specific vendor designation. Semaglutide itself is an FDA-approved, patent-protected pharmaceutical (Novo Nordisk); research vendor analogs are structurally distinct compounds with unknown pharmacological equivalence to the approved drug.

PEP-TRZ is a designation used by certain research peptide vendors. Based on vendor naming conventions in which "PEP" denotes a proprietary peptide formulation and "TRZ" refers to tirzepatide (LY3298176), this designation most probably refers to a research-grade tirzepatide analog or uncharacterized GLP-1/GIP dual receptor agonist variant. **No published peer-reviewed research exists for PEP-TRZ as a named compound.** No molecular formula, sequence, mechanism, or safety data has been publicly disclosed for this specific vendor designation. Tirzepatide is an FDA-approved, patent-protected pharmaceutical (Eli Lilly); research vendor analogs are structurally distinct compounds with unknown pharmacological equivalence to the approved drug.

PT-141 (bremelanotide) is a cyclic heptapeptide melanocortin receptor agonist developed originally as a metabolite of Melanotan II. It was the first centrally-acting agent approved for hypoactive sexual desire disorder (HSDD) in premenopausal women, marketed as Vyleesi by Palatin Technologies/AMAG Pharmaceuticals and approved by the FDA in 2019. Unlike phosphodiesterase inhibitors (sildenafil, tadalafil) that act on peripheral vascular mechanisms, PT-141 acts directly on melanocortin-4 receptors (MC4R) in the hypothalamus to enhance sexual desire and arousal through central nervous system pathways. The peptide differs from its parent compound Melanotan II by the removal of the amino terminal and C-terminal amide, producing a metabolite that retains MC4R activity for sexual function while substantially reducing MC1R-mediated tanning effects. Its approval represented a paradigm shift in sexual medicine — from treating the mechanical aspects of sexual response to targeting the neural circuits underlying desire itself.

Retatrutide (LY-3437943) is a first-in-class triple agonist peptide that simultaneously activates the glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and glucagon receptors. Developed by Eli Lilly, it represents an evolution beyond dual GIP/GLP-1 agonists like tirzepatide by incorporating glucagon receptor activation, which adds thermogenic energy expenditure and hepatic lipid metabolism to the weight loss and glycemic control mechanisms of incretin agonism. The peptide is a modified 39-amino acid chain with a C20 fatty diacid moiety that enables albumin binding and once-weekly dosing. As of 2024, it is in Phase 3 clinical trials for obesity and type 2 diabetes, with prior Phase 2 results generating substantial attention for producing the largest weight reductions seen in clinical trials at the time of publication.

Semaglutide is a long-acting glucagon-like peptide-1 receptor agonist (GLP-1 RA) developed by Novo Nordisk. It is a 31-amino acid peptide analogue of human GLP-1 with two key modifications: an alpha-aminoisobutyric acid substitution at position 8 that confers resistance to dipeptidyl peptidase-4 (DPP-4) degradation, and a C18 fatty diacid chain attached to lysine at position 26 via a linker that enables non-covalent albumin binding, extending the half-life to approximately 7 days. Semaglutide is approved for type 2 diabetes (Ozempic, subcutaneous; Rybelsus, oral) and chronic weight management (Wegovy, subcutaneous). It is among the most commercially successful and clinically studied peptide therapeutics, with major outcomes trials demonstrating benefits in glycemic control, weight reduction, and cardiovascular risk reduction. The oral formulation (Rybelsus) represents a significant pharmaceutical achievement as the first oral GLP-1 RA, using a sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC) absorption enhancer.

Survodutide (development code BI 456906) is a once-weekly subcutaneous glucagon receptor (GCGR) and GLP-1 receptor (GLP-1R) dual agonist developed by Boehringer Ingelheim in collaboration with Zealand Pharma. It is an acylated peptide engineered for extended half-life via albumin binding, enabling weekly dosing. Survodutide is the most clinically advanced compound in this analysis, with active Phase 3 trials (SYNCHRONIZE-1, SYNCHRONIZE-2, and SYNCHRONIZE-CVOT) enrolling patients globally. The FDA has granted survodutide both Fast Track Designation and Breakthrough Therapy Designation for the treatment of non-cirrhotic metabolic-associated steatohepatitis (MASH) with moderate-to-advanced fibrosis. The compound is not yet approved in any jurisdiction.

Tirzepatide is a first-in-class dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist developed by Eli Lilly. It is a 39-amino acid synthetic peptide based on the native GIP sequence with modifications that enable dual receptor agonism and a C20 fatty diacid side chain for albumin binding and once-weekly dosing. Tirzepatide is approved for type 2 diabetes (Mounjaro) and chronic weight management (Zepbound). The peptide has produced the largest weight reductions seen in pharmaceutical obesity trials. In the SURMOUNT-1 trial, the highest dose group achieved mean weight loss exceeding 20% — approaching the efficacy of bariatric surgery for the first time with a pharmacological agent. Its dual agonist mechanism represents a conceptual advance over single-target GLP-1 agonists, though the precise contribution of GIP receptor activation to its superior efficacy remains an active area of investigation.