Peptide Comparison Guide
Side-by-side scientific comparisons of research peptides. Mechanism of action, molecular properties, receptor targets, and key research citations.
This guide provides structured comparisons of commonly researched peptide pairs. Each comparison has its own page with a property-by-property comparison table, key mechanistic differences, and a research summary with citations. For definitions of technical terms used throughout these pages, see our peptide glossary.
BPC-157 vs TB-500 (Thymosin Beta-4)
BPC-157 and TB-500 are two of the most widely studied peptides in tissue repair research. While both are investigated for their regenerative properties, they differ substantially in origin, mechanism, and primary research applications.
Read the full comparisonSemaglutide vs Tirzepatide
Semaglutide and tirzepatide are both investigated for their effects on glucose metabolism and body composition. The critical distinction is that semaglutide is a single-target GLP-1 receptor agonist, while tirzepatide is a dual GIP/GLP-1 receptor agonist.
Read the full comparisonIpamorelin vs CJC-1295
Ipamorelin and CJC-1295 are both studied for their growth hormone (GH) releasing properties, but they operate through different receptor systems. Ipamorelin is a ghrelin mimetic (GHSR agonist), while CJC-1295 is a growth hormone-releasing hormone (GHRH) analog.
Read the full comparisonPT-141 (Bremelanotide) vs Melanotan II
PT-141 (bremelanotide) and Melanotan II are both melanocortin receptor agonists derived from the alpha-melanocyte-stimulating hormone (alpha-MSH) scaffold. However, they differ in receptor selectivity and the breadth of their studied effects.
Read the full comparisonNAD+ vs NMN (Nicotinamide Mononucleotide)
NAD+ (nicotinamide adenine dinucleotide) and NMN (nicotinamide mononucleotide) are both central to cellular energy metabolism and aging research. NAD+ is the active coenzyme itself, while NMN is its direct biosynthetic precursor.
Read the full comparisonTirzepatide vs Retatrutide
Tirzepatide and retatrutide are next-generation incretin-based compounds studied for metabolic research. Tirzepatide is a dual GIP/GLP-1 receptor agonist, while retatrutide adds a third mechanism: glucagon receptor agonism.
Read the full comparisonSemaglutide vs Retatrutide
Semaglutide and retatrutide sit at opposite ends of the incretin receptor spectrum. Semaglutide is a selective single-receptor GLP-1 agonist with the most extensive clinical evidence in its class, while retatrutide engages three receptors: GIP, GLP-1, and glucagon.
Read the full comparisonCagrilintide vs Semaglutide
Cagrilintide and semaglutide act on entirely different appetite-regulation systems. Cagrilintide is a long-acting amylin analog, while semaglutide is a GLP-1 receptor agonist. The two are frequently studied together because their mechanisms are complementary.
Read the full comparisonSelank vs Semax
Selank and Semax are short synthetic peptides developed at the Institute of Molecular Genetics in Moscow and studied extensively in Russian neuropharmacology research. Selank is investigated primarily for anxiolytic properties, Semax for nootropic and neuroprotective effects.
Read the full comparisonGHK-Cu vs AHK-Cu
GHK-Cu and AHK-Cu are both copper-binding tripeptides, but they are studied for different tissue targets. GHK-Cu is the classic skin-remodeling copper peptide, while AHK-Cu research concentrates on hair follicle biology.
Read the full comparisonGHRP-2 vs GHRP-6
GHRP-2 and GHRP-6 are first-generation synthetic growth hormone releasing hexapeptides acting on the ghrelin receptor. They differ mainly in potency of GH release and the strength of their appetite-stimulating effect.
Read the full comparisonSermorelin vs Tesamorelin
Sermorelin and tesamorelin are both growth hormone-releasing hormone (GHRH) analogs, but they differ in length, stability, and research pedigree. Sermorelin is the minimal functional GHRH fragment, while tesamorelin is a stabilized full-length analog with completed phase 3 programs.
Read the full comparisonMelanotan 1 (Afamelanotide) vs Melanotan II
Melanotan 1 (afamelanotide) and Melanotan II are both synthetic analogs of alpha-melanocyte-stimulating hormone developed at the University of Arizona, but they diverged sharply: Melanotan 1 is a linear, MC1R-focused peptide that became an approved drug, while Melanotan II is a smaller cyclic analog with broad receptor activity.
Read the full comparisonMOTS-c vs SS-31 (Elamipretide)
MOTS-c and SS-31 are both studied in mitochondrial research but approach the organelle from opposite directions. MOTS-c is a mitochondrial-derived signaling peptide that acts on nuclear gene expression and metabolism, while SS-31 is a synthetic peptide that physically targets the inner mitochondrial membrane.
Read the full comparisonIGF-1 LR3 vs HGH 191AA (Somatropin)
IGF-1 LR3 and HGH 191AA occupy different tiers of the same growth axis. HGH 191AA is recombinant human growth hormone, the upstream signal, while IGF-1 LR3 is a long-acting analog of insulin-like growth factor 1, the downstream mediator through which many GH effects are expressed.
Read the full comparisonFrequently Asked Questions
What is the difference between BPC-157 and TB-500?
BPC-157 is a synthetic pentadecapeptide derived from gastric juice that modulates nitric oxide pathways and growth factor expression, primarily studied for gastrointestinal and tendon repair. TB-500 is a fragment of thymosin beta-4 that regulates actin polymerization and cell migration, primarily studied for cardiac tissue regeneration and wound healing. They differ in origin, molecular weight (1,419 Da vs 4,963 Da), and mechanism of action.
Full BPC-157 vs TB-500 (Thymosin Beta-4) comparison →How does semaglutide compare to tirzepatide?
Semaglutide is a selective GLP-1 receptor agonist with a ~7-day half-life, while tirzepatide is a dual GIP/GLP-1 receptor agonist with a ~5-day half-life. The key distinction is that tirzepatide activates two incretin receptors simultaneously, which may account for the greater metabolic effects observed in head-to-head clinical trials such as SURPASS-2.
Full Semaglutide vs Tirzepatide comparison →Can ipamorelin and CJC-1295 be used together in research?
Yes, ipamorelin and CJC-1295 (mod GRF 1-29) are frequently studied in combination because they target different receptor systems. Ipamorelin activates the ghrelin receptor (GHSR-1a) for pulsatile growth hormone release, while CJC-1295 amplifies GHRH receptor signaling. Their complementary mechanisms may produce synergistic effects on GH secretion patterns.
Full Ipamorelin vs CJC-1295 comparison →What is the difference between PT-141 and Melanotan II?
PT-141 (bremelanotide) is a selective MC3R/MC4R agonist engineered from Melanotan II to target central nervous system melanocortin pathways without significant pigmentation effects. Melanotan II is a non-selective melanocortin agonist that activates MC1R through MC5R, producing both pigmentation and CNS effects. PT-141 was specifically designed to remove the MC1R-mediated melanogenesis activity of Melanotan II.
Full PT-141 (Bremelanotide) vs Melanotan II comparison →Is NMN or NAD+ better for research on aging?
NAD+ is the active coenzyme used by over 500 enzymes including sirtuins and PARPs, but faces bioavailability challenges due to its larger molecular weight (663 Da). NMN is its direct precursor (334 Da) and may be more efficiently absorbed via the Slc12a8 transporter. Current research suggests NMN supplementation effectively raises tissue NAD+ levels, but the optimal approach depends on the specific research model and endpoints being studied.
Full NAD+ vs NMN (Nicotinamide Mononucleotide) comparison →What is the difference between tirzepatide and retatrutide?
Tirzepatide is a dual GIP/GLP-1 receptor agonist, while retatrutide is a triple agonist that adds glucagon receptor activation. The glucagon component is associated with increased energy expenditure, and retatrutide produced up to ~24% mean weight reduction at 48 weeks in phase 2 research versus ~21% at 72 weeks for tirzepatide in SURMOUNT-1. Tirzepatide has the more mature clinical dataset.
Full Tirzepatide vs Retatrutide comparison →How does semaglutide compare to retatrutide?
Semaglutide is a selective GLP-1 receptor agonist with completed phase 3 and cardiovascular outcome trials. Retatrutide is an investigational triple agonist targeting GIP, GLP-1, and glucagon receptors; its glucagon component adds increased energy expenditure. Phase 2 retatrutide research reported up to ~24% mean weight reduction at 48 weeks versus ~15% for semaglutide in STEP-1, but retatrutide’s long-term dataset is much smaller.
Full Semaglutide vs Retatrutide comparison →What is the difference between cagrilintide and semaglutide?
Cagrilintide is a long-acting amylin analog that promotes satiation through amylin and calcitonin receptors in the hindbrain, while semaglutide is a GLP-1 receptor agonist acting on incretin pathways. Both have ~7-day half-lives. They engage independent systems, and combination research (CagriSema) studies whether using both simultaneously produces greater metabolic effects than either alone.
Full Cagrilintide vs Semaglutide comparison →What is the difference between Selank and Semax?
Selank is a tuftsin-derived heptapeptide studied for anxiolytic effects via GABAergic modulation and enkephalinase inhibition. Semax is an ACTH(4-7)-derived heptapeptide studied for nootropic and neuroprotective effects via BDNF upregulation. Both were developed in Russia, share a stabilizing Pro-Gly-Pro tail, and have very short plasma half-lives with effects that outlast circulating levels.
Full Selank vs Semax comparison →What is the difference between GHK-Cu and AHK-Cu?
Both are copper-binding tripeptides, but GHK-Cu (glycyl-histidyl-lysine) is a naturally occurring plasma peptide studied for skin remodeling, collagen synthesis, and wound healing, while AHK-Cu (alanyl-histidyl-lysine) is a synthetic analog studied mainly for hair follicle biology, including dermal papilla cell proliferation and VEGF expression. GHK-Cu has a much larger research literature.
Full GHK-Cu vs AHK-Cu comparison →What is the difference between GHRP-2 and GHRP-6?
Both are hexapeptide ghrelin mimetics acting on GHSR-1a. GHRP-2 is generally the more potent GH secretagogue and saw clinical diagnostic use in Japan as pralmorelin, while GHRP-6 produces a much stronger ghrelin-like appetite stimulus. Both can transiently affect cortisol and prolactin at higher concentrations, unlike the more selective ipamorelin.
Full GHRP-2 vs GHRP-6 comparison →What is the difference between sermorelin and tesamorelin?
Both are GHRH receptor agonists. Sermorelin is the minimal GHRH(1-29) fragment with a ~10-20 minute half-life, historically used in GH deficiency. Tesamorelin is a full-length GHRH(1-44) analog stabilized against DPP-4 degradation, with a longer half-life and phase 3 evidence for visceral fat reduction in HIV-associated lipodystrophy.
Full Sermorelin vs Tesamorelin comparison →What is the difference between Melanotan 1 and Melanotan II?
Melanotan 1 (afamelanotide) is a linear 13-amino-acid alpha-MSH analog selective for MC1R, studied for photoprotective pigmentation and approved as Scenesse for erythropoietic protoporphyria. Melanotan II is a smaller cyclic analog that activates MC1R through MC5R non-selectively, producing pigmentation plus central effects, and is the structural parent of PT-141.
Full Melanotan 1 (Afamelanotide) vs Melanotan II comparison →What is the difference between MOTS-c and SS-31?
MOTS-c is a 16-amino-acid peptide encoded by mitochondrial DNA that signals to the nucleus and activates AMPK, studied for exercise-mimetic and insulin-sensitivity effects. SS-31 (elamipretide) is a synthetic tetrapeptide that binds cardiolipin in the inner mitochondrial membrane, stabilizing the electron transport chain and reducing ROS, studied in mitochondrial dysfunction and ischemia-reperfusion models.
Full MOTS-c vs SS-31 (Elamipretide) comparison →What is the difference between IGF-1 LR3 and HGH 191AA?
HGH 191AA is recombinant human growth hormone, identical to the endogenous 191-amino-acid hormone; it acts on the GH receptor and induces the liver to produce IGF-1. IGF-1 LR3 is an engineered IGF-1 analog that acts directly on the IGF-1 receptor and evades IGF binding proteins, giving it a ~20-30 hour active half-life versus hours for GH. They target different receptors at different levels of the same growth axis.
Full IGF-1 LR3 vs HGH 191AA (Somatropin) comparison →Disclaimer: All compounds referenced on this page are sold for research and laboratory use only. The comparisons presented are based on published scientific literature and are intended for educational and informational purposes. This content does not constitute medical advice. Researchers should consult primary literature and applicable regulations before designing study protocols.