Pep-Ed · 04 · The landscape
Categories
of peptides
04 · The landscape
Categories of peptides
Peptides are usually grouped by what they are being studied for. Pick a category to see how it works, what the research says, each compound’s common names and where it stands.
Metabolic & Incretin
Weight management · Appetite and cravings · Blood-sugar control
Growth Hormone Secretagogues
Growth hormone deficiency · Body composition (lean mass, fat) · Sleep quality
Tissue Repair & Recovery
Tendon, ligament and muscle injuries · Wound healing · Gut lining and digestive inflammation
Neuropeptides & Cognitive
Focus and memory · Stress and anxiety · Sleep
Skin, Cosmetic & Longevity
Skin firmness and collagen · Fine lines and skin repair · Hair and wound healing
Reproductive & Signaling
Sexual desire (libido) · Social bonding · Labor and postpartum care (approved oxytocin)
How to read the evidence labels
Metabolic & Incretin
Most mimic the gut hormones (incretins such as GLP-1 and GIP, plus glucagon) that tell the body it has eaten: they slow digestion, signal fullness and help regulate insulin. Others act on fat metabolism or mitochondria.
What researchers are studying
TirzepatideBrand names Mounjaro®, Zepbound®
FDA-approved drug existsA dual GIP / GLP-1 receptor agonist taken once a week.
Studied forFDA-approved for type 2 diabetes and chronic weight management. In the SURMOUNT-1 trial, adults with obesity lost substantially more weight than with placebo over 72 weeks.
RetatrutideInvestigational code LY3437943
Some human dataAn investigational triple agonist of the GIP, GLP-1 and glucagon receptors.
Studied forBeing studied by Eli Lilly for obesity and type 2 diabetes in phase 3 (TRIUMPH) trials. It is not FDA-approved; Lilly has said it plans to file for approval in 2027.
TesamorelinBrand name Egrifta®
FDA-approved drug existsA growth hormone-releasing hormone (GHRH) analog.
Studied forFDA-approved to reduce excess abdominal fat in adults with HIV-associated lipodystrophy. Also studied for visceral fat and liver fat.
MOTS-cMitochondrial ORF of the 12S rRNA type-c
Mostly lab & animalA 16-amino-acid peptide encoded by mitochondrial DNA, discovered in 2015.
Studied forIn mice it improved insulin sensitivity and protected against diet-induced weight gain. Human data are mostly observational (blood levels), not treatment trials.
Good to know. The most-studied class on this page, and also the one the FDA has warned about most. Common side effects in trials are gastrointestinal (nausea, diarrhea, constipation). Approved brand versions are prescription drugs; the FDA has warned consumers about unapproved and counterfeit GLP-1 products. FDA: concerns with unapproved GLP-1 drugs →
Growth Hormone Secretagogues
These signal the pituitary gland to release more of the body's own growth hormone (GH). GHRH analogs (sermorelin, CJC-1295) act on the GHRH receptor; GHRPs (ipamorelin, hexarelin) act on the ghrelin receptor. The two types are often paired.
What researchers are studying
SermorelinGHRH (1-29); formerly sold as Geref®
Some human dataA copy of the first 29 amino acids of natural growth hormone-releasing hormone.
Studied forWas FDA-approved for growth hormone deficiency in children. The brand was discontinued for manufacturing reasons; in 2013 FDA determined it was not withdrawn for safety or effectiveness. Studied for adult GH decline.
CJC-1295 (no DAC)Modified GRF (1-29), Mod GRF
Some human dataA GHRH analog modified to resist breakdown; shorter-acting than the DAC version.
Studied forStudied to boost natural GH pulses. Published human trials used the long-acting DAC version, so evidence for the no-DAC form is limited.
IpamorelinA growth hormone-releasing peptide (GHRP)
Some human dataA five-amino-acid ghrelin-receptor agonist.
Studied forDescribed in 1998 as the first selective GH secretagogue (little effect on cortisol or prolactin in animal studies). Tested in a human trial for post-surgery gut recovery.
HexarelinA growth hormone-releasing peptide (GHRP)
Some human dataA six-amino-acid ghrelin-receptor agonist and one of the most potent GHRPs.
Studied forStudied for GH release and for effects on the heart. The GH response can fade with continued use.
CJC-1295 + IpamorelinGHRH + GHRP blend
Mostly lab & animalCombines both GH pathways in one vial.
Studied forThe rationale is that the two pathways work together. No published clinical studies have tested this blend itself.
Good to know. Raising GH also raises IGF-1 and can affect blood sugar, fluid retention and appetite. Growth-promoting signals are a theoretical concern for anyone with a history of cancer. All GH secretagogues are prohibited in sport by WADA. WADA Prohibited List →
Tissue Repair & Recovery
Studied for their roles in blood-vessel formation, cell migration and inflammation signaling, the processes that drive healing.
What researchers are studying
BPC-157Body Protection Compound-157
Mostly lab & animalA 15-amino-acid fragment of a protein found in stomach juice.
Studied forIn animal studies it improved healing of tendon, ligament, muscle, bone and gut injuries. A 2025 systematic review found 35 preclinical studies and just 1 clinical study; a small 2025 pilot looked at IV safety in people.
TB-500Thymosin beta-4 fragment
Mostly lab & animalA synthetic fragment of thymosin beta-4, a protein involved in cell movement and repair.
Studied forStudied in animals for wound, muscle and tissue repair. The full thymosin beta-4 protein has reached early human trials for eye surface healing.
BPC-157 + TB-500Repair blend
Mostly lab & animalCombines the two repair peptides above.
Studied forCombined for overlapping repair pathways. No published clinical studies have tested this blend.
KPVLysine-proline-valine; alpha-MSH fragment
Mostly lab & animalA three-amino-acid fragment of alpha-melanocyte-stimulating hormone.
Studied forReduced intestinal inflammation in mouse colitis models. The FDA has said it has identified no human exposure data.
IGF-1 LR3Long R3 IGF-1
Mostly lab & animalA modified, longer-acting analog of insulin-like growth factor 1, used mainly in cell-culture research.
Studied forDesigned to resist the proteins that normally bind IGF-1, so it stays active longer. No human clinical trials; IGF-1 can lower blood sugar. It is prohibited in sport and has turned up in black-market products.
Good to know. The most popular category online, and the one with the thinnest human evidence. In October 2026 HHS announced it would not take enforcement action against licensed 503A pharmacies compounding BPC-157, TB-500 and KPV (plus three others) under strict conditions. That does not make them FDA-approved. BPC-157 and TB-500 are prohibited in sport. HHS policy, Federal Register (Oct 30, 2026) →
Neuropeptides & Cognitive
Short peptides that act on brain signaling: stress hormones, neurotrophic (nerve-growth) factors and sleep regulation.
What researchers are studying
SemaxACTH (4-10) analog
Some human dataA modified fragment of the stress hormone ACTH, usually given as a nasal spray.
Studied forUsed in Russia after stroke and for cognitive conditions; lab studies show effects on nerve-growth factors. Western clinical evidence is limited.
SelankTuftsin analog
Some human dataA synthetic analog of tuftsin, an immune-system peptide.
Studied forDeveloped in Russia as an anti-anxiety peptide and studied in small trials of generalized anxiety.
DSIPDelta sleep-inducing peptide
Some human dataA nine-amino-acid peptide first isolated in 1977 during deep sleep in rabbits.
Studied forStudied for sleep and stress, with inconsistent results. How it works is still unresolved.
Good to know. Semax and Selank were developed and are used clinically in Russia, so most published research is Russian-language and small-scale. None of these is FDA-approved.
Skin, Cosmetic & Longevity
Peptides and coenzymes that support collagen, skin repair and cellular energy (mitochondria), which decline with age.
What researchers are studying
GHK-CuCopper peptide
Some human dataA naturally occurring copper-binding tripeptide found in blood plasma; levels fall with age.
Studied forWidely used in topical skincare; studied for collagen production, skin firmness and wound healing. Evidence for injected forms is limited.
GLOWGHK-Cu + BPC-157 + TB-500
Mostly lab & animalA three-peptide blend pairing the copper peptide with two repair peptides.
Studied forCombines skin- and repair-focused compounds. No published studies have tested the blend itself.
KLOWGHK-Cu + KPV + BPC-157 + TB-500
Mostly lab & animalGLOW plus KPV.
Studied forAdds KPV for its anti-inflammatory research profile. No published studies have tested the blend itself.
SS-31Elamipretide; brand name Forzinity®
FDA-approved drug existsA four-amino-acid peptide that targets cardiolipin in the inner mitochondrial membrane.
Studied forIn September 2025 the FDA granted accelerated approval for Barth syndrome, a rare mitochondrial disease. Also studied in mitochondrial myopathy and heart failure.
NAD+Nicotinamide adenine dinucleotide (not a peptide)
Some human dataA coenzyme found in every cell, essential to energy metabolism and DNA repair.
Studied forNAD+ levels decline with age. Human trials (mostly oral precursors such as NR and NMN) show NAD+ levels can be raised safely, but clinical benefits are still mixed.
Good to know. GHK-Cu has the longest track record, mainly in topical skincare. Blends combine compounds that have not been studied together. NAD+ is a coenzyme, not a peptide; it is grouped here because it is used for the same goals.
Reproductive & Signaling
Peptides that act on the brain's desire, bonding and reproductive signaling pathways.
What researchers are studying
PT-141Bremelanotide; brand name Vyleesi®
FDA-approved drug existsA melanocortin-receptor agonist that acts in the brain rather than on blood flow.
Studied forFDA-approved in 2019 for acquired, generalized hypoactive sexual desire disorder (low sexual desire) in premenopausal women.
OxytocinBrand name Pitocin® (IV/IM)
FDA-approved drug existsA natural nine-amino-acid hormone often called the 'bonding hormone'.
Studied forFDA-approved in hospitals to start or strengthen labor and control bleeding after birth. Nasal oxytocin has been studied for social connection and bonding, with mixed results.
Good to know. Both have FDA-approved versions for narrow uses, with known side effects: bremelanotide commonly causes nausea, flushing and headache and can briefly raise blood pressure.
All categories at a glance
The evidence column counts compounds in each category: ● FDA-approved drug exists ● some human data ● mostly lab & animal.
| Category | How they work | Studied for | Common names | FDA-approved examples | Evidence |
|---|---|---|---|---|---|
| Metabolic & Incretin | Mimic gut hormones that control appetite, digestion and insulin | Weight management, Appetite and cravings, Blood-sugar control, Abdominal (visceral) fat, Insulin sensitivity | Tirzepatide, Retatrutide, Tesamorelin, MOTS-c | Tirzepatide (Mounjaro®, Zepbound®), Tesamorelin (Egrifta®) | 2 1 1 |
| Growth Hormone Secretagogues | Prompt the pituitary to release the body's own growth hormone | Growth hormone deficiency, Body composition (lean mass, fat), Sleep quality, Recovery, Age-related GH decline | Sermorelin, CJC-1295 (no DAC), Ipamorelin, Hexarelin, CJC-1295 + Ipamorelin | None | 4 1 |
| Tissue Repair & Recovery | Influence blood-vessel growth, cell migration and inflammation | Tendon, ligament and muscle injuries, Wound healing, Gut lining and digestive inflammation, Joint discomfort, Inflammation | BPC-157, TB-500, BPC-157 + TB-500, KPV, IGF-1 LR3 | None | 5 |
| Neuropeptides & Cognitive | Act on brain signaling for stress, nerve growth and sleep | Focus and memory, Stress and anxiety, Sleep, Recovery after stroke | Semax, Selank, DSIP | None | 3 |
| Skin, Cosmetic & Longevity | Support collagen, skin repair and mitochondrial energy | Skin firmness and collagen, Fine lines and skin repair, Hair and wound healing, Mitochondrial energy, Healthy aging | GHK-Cu, GLOW, KLOW, SS-31, NAD+ | SS-31 (Forzinity®) | 1 2 2 |
| Reproductive & Signaling | Act on brain pathways for desire and bonding | Sexual desire (libido), Social bonding, Labor and postpartum care (approved oxytocin) | PT-141, Oxytocin | PT-141 (Vyleesi®), Oxytocin (Pitocin® (IV/IM)) | 2 |
References
Sources
- Muttenthaler et al., Trends in peptide drug discovery, Nat Rev Drug Discov 2021
- Wang et al., Therapeutic peptides: current applications and future directions, 2022
- Ashraf et al., Safety and risk of no-prescription online semaglutide purchases, JAMA Netw Open 2024
- Choules et al., NMR reveals an undeclared constituent in custom synthetic peptides, 2020
- FDA: Bulk drug substances that may present significant safety risks in compounding
- FDA: Concerns with unapproved GLP-1 drugs used for weight loss
- HHS enforcement discretion policy for 503A peptide compounding, Federal Register, Oct 30 2026
- WADA Prohibited List
- Tirzepatide: SURMOUNT-1, NEJM 2022
- Retatrutide: Phase 2 trial, NEJM 2023
- Retatrutide: Lilly: what to know about retatrutide
- Tesamorelin: Falutz et al., NEJM 2007
- MOTS-c: Lee et al., Cell Metabolism 2015
- MOTS-c: Kim et al., Physiol Rep 2019
- Sermorelin: Walker, Clin Interv Aging 2006
- Sermorelin: FDA determination, Federal Register 2013
- CJC-1295 (no DAC): Teichman et al., JCEM 2006 (DAC version)
- Ipamorelin: Raun et al., Eur J Endocrinol 1998
- Ipamorelin: Beck et al., Int J Colorectal Dis 2014
- Hexarelin: Mao et al., J Geriatr Cardiol 2014
- BPC-157: Vasireddi et al., systematic review 2025
- BPC-157: Lee et al., human IV safety pilot 2025
- BPC-157: Seiwerth et al., wound-healing review 2021
- TB-500: Sosne, Expert Opin Biol Ther 2018 (thymosin beta-4)
- KPV: Dalmasso et al., Gastroenterology 2008
- IGF-1 LR3: Black-market detection study, 2010
- Semax: Stroke-stage study, 2018 (Russian)
- Semax: Neurotrophin gene study, 2010
- Selank: Zozulia et al., GAD trial 2008 (Russian)
- DSIP: Kovalzon et al., J Neurochem 2006
- GHK-Cu: Pickart et al., Int J Mol Sci 2018
- SS-31: FDA approval announcement, 2025
- SS-31: TAZPOWER extension, Genet Med 2024
- NAD+: Nature Metabolism review, 2025
- NAD+: Systematic review, Am J Physiol 2024
- PT-141: RECONNECT phase 3 trials, Obstet Gynecol 2019
- Oxytocin: Keech et al., meta-analysis 2018
Educational information only. Pep-Ed summarizes published research so you can make informed decisions with a licensed healthcare provider. It is not medical advice and does not describe how to use any product.
Unless a product page states otherwise, BioDynamics Labs products are not FDA-approved drugs and are not intended to diagnose, treat, cure or prevent any disease. Brand names (Mounjaro®, Zepbound®, Egrifta®, Vyleesi®, Pitocin®, Forzinity®) are trademarks of their owners and refer to FDA-approved products not sold by BioDynamics Labs.
Last reviewed November 2026.