Encyclopedia

AOD-9604 is a synthetic peptide based on the C-terminal lipolytic fragment of human growth hormone (residues 176-191, with an added tyrosine). It was developed as an anti-obesity agent intended to stimulate fat metabolism without growth hormone's effects on IGF-1 or blood sugar. It received FDA 'Generally Recognized As Safe' (GRAS) status as a food ingredient but is not FDA-approved as a drug, and its pivotal human obesity trials did not meet their primary weight-loss endpoint.

BPC-157 is a synthetic 15-amino-acid peptide derived from a partial sequence of a protein found in human gastric juice. It has been studied extensively in rodent models for tissue repair, tendon and ligament healing, and gastrointestinal protection. As of 2026 there is essentially no published human clinical efficacy data, and it is not approved by the FDA for any use.

Cerebrolysin is not a single peptide but a standardized mixture of low-molecular-weight peptide fragments (~15-25%) and free amino acids (~75-85%) produced by controlled enzymatic hydrolysis of porcine brain protein. It is registered as a medicine in over 40 countries (including Austria, Germany, Russia, and China) for stroke, traumatic brain injury, and dementia, but is not FDA-approved and remains a research-use-only compound in the United States. Its evidence base is unusually large for a peptide product but genuinely mixed: some meta-analyses show benefit, while the largest stroke trial was neutral and a Cochrane review rated dementia evidence as very low quality.

CJC-1295 (no DAC), also called Modified GRF (1-29), is a synthetic analog of growth-hormone-releasing hormone (GHRH). It binds the GHRH receptor on the pituitary to stimulate pulsatile GH and IGF-1 release. The 'no DAC' form is short-acting (~30 minutes), which preserves natural pulsatility, in contrast to CJC-1295 with DAC (half-life of several days). It is not FDA-approved and is prohibited in sport.

CJC-1295 with DAC is a long-acting analog of growth-hormone-releasing hormone (GHRH) fragment (1-29), chemically modified with a Drug Affinity Complex (DAC) that covalently binds circulating albumin. This extends its half-life from minutes to approximately 6-8 days, allowing once- or twice-weekly dosing with sustained GH and IGF-1 elevation. It is a distinct entry from CJC-1295 (no DAC) / Modified GRF(1-29), which shares the same peptide backbone but clears in about 30 minutes.

Dihexa is a small-molecule peptide derivative of angiotensin IV, developed at Washington State University as a potentiator of hepatocyte growth factor (HGF) signaling through the c-Met receptor, reported to drive synaptogenesis at extremely low concentrations in preclinical assays. It has zero completed human clinical trials, and its two foundational research papers have serious, disclosed integrity issues: one carries a formal Expression of Concern and the other was retracted in 2025. It is not FDA-approved.

DSIP (delta sleep-inducing peptide) is a naturally occurring nonapeptide first isolated from the cerebral venous blood of sleeping rabbits, associated with slow-wave (delta) EEG activity. It is found endogenously in human plasma and tissues, with levels correlated to circadian rhythm. Its gene, precursor, and receptor have never been identified, and modern reproducibility of its original sleep-inducing effects is limited. It is not FDA-approved.</br>

Epitalon is a synthetic tetrapeptide (Ala-Glu-Asp-Gly) developed in Russia as a synthetic analog of epithalamin, a bovine pineal-gland extract. It is studied in longevity research for reported telomerase activation, telomere maintenance, and circadian/melatonin regulation. Nearly all published research originates from a single Russian research group, and it has not undergone Western-standard randomized controlled trials. It is not FDA-approved.

GHK-Cu is the copper(II) complex of the naturally occurring tripeptide glycyl-L-histidyl-L-lysine (GHK). It is found endogenously in human plasma, saliva, and urine, with plasma levels declining markedly with age. It is widely used as a topical cosmetic ingredient for skin remodeling and collagen synthesis, where human evidence is strongest; systemic and injectable anti-aging uses are far less validated and not FDA-approved.

GHRP-6 is the original growth hormone-releasing hexapeptide, developed in 1984 as the first compound shown to stimulate GH release through a mechanism independent of GHRH. It acts as an agonist at the ghrelin receptor (GHS-R1a) and is distinguished from later GHRPs like ipamorelin by pronounced appetite stimulation and modest cortisol/prolactin elevation. It is not FDA-approved.

Glutathione is an endogenous tripeptide (gamma-L-glutamyl-L-cysteinylglycine) and the body's most abundant intracellular antioxidant, protecting cells from oxidative damage and supporting detoxification pathways. It is a genuine tripeptide (unlike some other compounds marketed alongside it), sold both as an approved injectable in some countries for specific medical uses and, more commonly in wellness/aesthetic markets, as an unapproved 'skin-brightening' or general antioxidant IV/injectable.

Somatropin is recombinant human growth hormone (rhGH) -- a bioidentical, 191-amino-acid copy of the growth hormone naturally secreted by the anterior pituitary. It is FDA-approved under multiple brand names for a specific list of growth-disorder and deficiency indications, and separately (as Serostim) for HIV-associated wasting. Unlike the GH secretagogues elsewhere in this encyclopedia (e.g., ipamorelin, CJC-1295, GHRP-6), somatropin supplies growth hormone directly rather than stimulating the pituitary to release its own.

Ipamorelin is a synthetic pentapeptide and selective agonist of the ghrelin / growth hormone secretagogue receptor (GHS-R). It stimulates pulsatile growth hormone (GH) release from the pituitary and is notably selective — it does not meaningfully raise ACTH, cortisol, or prolactin. It is not FDA-approved, is prohibited in sport, and reached only phase II trials before being discontinued for lack of efficacy in its tested indication.

KPV is a tripeptide (Lys-Pro-Val) corresponding to the C-terminal sequence of alpha-melanocyte-stimulating hormone (alpha-MSH). It is studied for anti-inflammatory effects, particularly in intestinal inflammation (inflammatory bowel disease models) and skin conditions, and can act both systemically and topically. It is not FDA-approved.

Mazdutide is a long-acting synthetic oxyntomodulin analog and dual agonist of the GLP-1 and glucagon receptors, co-developed by Innovent Biologics and Eli Lilly. It is approved as a prescription drug in China for weight management but remains investigational in the United States, with no FDA approval as of this review.

Melanotan II is a synthetic, non-selective melanocortin receptor agonist developed at the University of Arizona as a tanning agent. It activates MC1R, MC3R, MC4R, and MC5R with comparable affinity, producing skin pigmentation and, as an incidental finding in early trials, erectile/libido effects. It is not FDA-approved or approved by any regulatory agency for any use, and carries documented safety concerns distinct from its FDA-approved, more selective derivative bremelanotide (PT-141).

MOTS-c is a 16-amino-acid mitochondrial-derived peptide encoded by the mitochondrial MT-RNR1 (12S rRNA) gene. It regulates metabolism — promoting glucose uptake and insulin sensitivity via the AMPK pathway — and is upregulated by exercise, leading to its description as an 'exercise mimetic.' It is studied for metabolic and aging-related applications but is not FDA-approved.

NAD+ (nicotinamide adenine dinucleotide) is an essential coenzyme found in every living cell, required for cellular energy (ATP) production, DNA repair, and as a substrate for sirtuin enzymes involved in aging biology. It is not a peptide (it is a dinucleotide) but is widely marketed alongside peptides as an IV or subcutaneous infusion for energy, cognition, and anti-aging. It is not FDA-approved as a drug for any of these marketed indications; controlled human trial evidence for IV/injectable NAD+ specifically is limited.

PEG-MGF is a pegylated (polyethylene-glycol-conjugated) version of Mechano Growth Factor (MGF), the C-terminal E-domain peptide of the IGF-1Ec splice variant that is naturally expressed within hours of mechanical muscle damage to activate satellite cells. Pegylation extends native MGF's half-life from minutes to hours-to-days. It has essentially no human clinical data and is not FDA-approved; the parent hormone IGF-1 (mecasermin) is separately FDA-approved for a specific pediatric deficiency indication, which should not be conflated with PEG-MGF itself.

PT-141 (bremelanotide) is an FDA-approved melanocortin receptor agonist marketed as Vyleesi for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. It acts through central (brain) arousal pathways rather than the vascular system, distinguishing it from erectile-dysfunction drugs. It is a subcutaneous injection taken before anticipated sexual activity.

Retatrutide is an investigational triple hormone receptor agonist, developed by Eli Lilly, that simultaneously activates the GIP, GLP-1, and glucagon receptors. It produced the largest pharmacological weight loss recorded to date in a phase 2 trial (24.2% at 48 weeks). It is NOT yet FDA-approved -- it remains in phase 3 (the TRIUMPH program) as of this review, and claims of approval circulating in some vendor/marketing material are inaccurate.

Selank is a synthetic heptapeptide analog of the immunomodulatory peptide tuftsin, developed at the Institute of Molecular Genetics of the Russian Academy of Sciences. It is studied as an anxiolytic that reduces anxiety without the sedation associated with benzodiazepines, and it also has immune-modulating activity. It is used clinically in Russia but is not FDA-approved.

Semaglutide is an FDA-approved glucagon-like peptide-1 (GLP-1) receptor agonist used to treat type 2 diabetes (Ozempic, Rybelsus) and for chronic weight management (Wegovy), with additional approved indications including reduction of major adverse cardiovascular events. It is a once-weekly injectable (also available as an oral tablet) with a half-life of about one week.

Semax is a synthetic heptapeptide analog of the ACTH(4-10) fragment, developed at the Institute of Molecular Genetics of the Russian Academy of Sciences. It is studied as a neuroprotective nootropic that upregulates the neurotrophins BDNF and NGF without stimulating cortisol. It is used clinically in Russia for some neurological indications but is not FDA-approved in the United States.

SS-31 (elamipretide) is a mitochondria-targeted tetrapeptide that binds and stabilizes cardiolipin in the inner mitochondrial membrane, improving mitochondrial function and reducing reactive oxygen species. It is an investigational drug (developed by Stealth BioTherapeutics) studied in mitochondrial diseases such as Barth syndrome, mitochondrial myopathy, and Friedreich's ataxia, as well as dry age-related macular degeneration. It is not FDA-approved.

TB-500 is a synthetic, N-acetylated heptapeptide (Ac-LKKTETQ) corresponding to the actin-binding fragment (residues 17-23) of thymosin beta-4 (Tβ4), a naturally occurring 43-amino-acid peptide involved in tissue repair, cell migration, and angiogenesis. It is frequently marketed as 'Thymosin Beta-4,' but the two are not identical. TB-500 is not FDA-approved, is prohibited in sport, and has no completed human efficacy trials as of 2026.

Tesamorelin is an FDA-approved synthetic analog of the full 44-amino-acid growth-hormone-releasing hormone (GHRH), marketed as Egrifta. It is approved specifically to reduce excess visceral abdominal fat in HIV-infected adults with lipodystrophy. Unlike exogenous growth hormone, it stimulates the pituitary's own pulsatile GH release via the GHRH receptor.

Thymosin Alpha-1 (INN thymalfasin) is a 28-amino-acid thymic peptide and immune modulator. It is approved in more than 30-35 countries under the brand name Zadaxin for chronic hepatitis B (and used for hepatitis C, certain cancers, and as an immune adjunct), but it is NOT FDA-approved in the United States. In the US it holds 503A Category 2 status, available by prescription through licensed compounding pharmacies in some states.

Tirzepatide is an FDA-approved dual GIP and GLP-1 receptor agonist, the first medication to activate both incretin receptors. It is approved for type 2 diabetes (Mounjaro) and chronic weight management and obstructive sleep apnea in obesity (Zepbound). It is a once-weekly subcutaneous injection with a half-life of about 5 days and has shown greater weight loss than selective GLP-1 agonists in trials.