A-Z Peptide Encyclopedia: Every Peptide, Graded by Evidence

The word "peptide" now covers everything from insulin and the GLP-1 blockbusters to unregulated research chemicals sold in gray-market vials. Lumping them together is how bad decisions get made. This index exists to keep them apart — to let you find any compound quickly and immediately see how strong (or weak) the human evidence for it actually is. Every entry links to a full monograph with indication-by-indication grading, dosing as reported in the literature, safety, and regulatory and anti-doping status.

This article is informational and editorial content only. It is not medical advice, not a protocol, and not a sourcing or buying guide. Many compounds listed here are not FDA-approved for human use, and several are sold only as "research chemicals, not for human consumption." Dosing figures in the monographs are reported strictly as they appear in the published literature. Consult a licensed clinician before any health decision.

How is every peptide graded?

Each efficacy claim carries an evidence grade, and the grade reflects the best-supported indication for that compound. The four tiers are deliberately strict, and they never let preclinical enthusiasm inflate into a human recommendation.

Two nuances matter throughout. First, the same molecule often carries a high grade for its approved use and a much lower grade for its popularized off-label use — a compound can be Grade A for one thing and Grade D for another. Second, several agents are graded A (negative): a large trial answered the question definitively, and the answer was that it does not work. AOD-9604 failed weight loss across six RCTs enrolling 893 people,9 and the oral secretagogue MK-677 reliably raises growth hormone and lean mass yet produced no benefit on strength, fracture recovery, or Alzheimer's over two years.10 This library is written from a functional and integrative, root-cause perspective, but that lens shapes only tone and emphasis — it never overrides or invents a sourced fact.14

Which peptides have the strongest evidence?

The Grade-A tier is dominated by approved metabolic and hormonal therapeutics. The GLP-1 and incretin family is the clearest example: semaglutide, liraglutide, dulaglutide, exenatide and lixisenatide are all supported by large Phase 3 programs, and the newer multi-agonists have pushed efficacy higher still. Tirzepatide, a dual GIP/GLP-1 co-agonist, beat semaglutide head-to-head in SURPASS-2,4 while the fixed-dose amylin-plus-GLP-1 combination CagriSema delivered roughly 22.7% mean weight reduction in REDEFINE-1.2 The GLP-1/glucagon dual agonists mazdutide5 and survodutide,6 and the amylin analog cagrilintide,3 all cleared Phase 3 or large placebo-controlled trials.

Beyond metabolism, the bone-anabolic PTH analogs teriparatide and abaloparatide reduce fractures in high-risk osteoporosis — the ACTIVE trial cut new vertebral fractures roughly 86% versus placebo.1 Among the melanocortins, afamelanotide is approved for photoprotection in erythropoietic protoporphyria,7 and bremelanotide (PT-141) is approved for hypoactive sexual desire disorder on two pivotal RCTs.8 Reproductive hormones (oxytocin, carbetocin, gonadotropins, hCG) and core metabolic peptides (insulin, glucagon, pramlintide,18 teduglutide) complete the strongly evidenced group. You can browse the full grading logic and the complete alphabetical roster of these compounds on the ClinicalTrials.gov registry, which underpins most of the Grade-A entries.

Which peptides are preclinical or unproven?

Most of the peptides that dominate fitness and longevity marketing sit at the bottom of the scale. The tissue-repair favorites BPC-157 and TB-500 have deep, internally consistent animal data but no completed human RCT, so they are graded C (preclinical only).13 The Pentadeca Arginate entries are graded D as distinct named products — a PubMed search for the term returns zero results — and only borrow BPC-157's rodent base to reach C at best. The Khavinson "bioregulators" and cytogens (epitalon, pinealon, cortagen, livagen, vilon, bronchogen, chonluten, cardiogen) rest on rodent and in-vitro work from a single research lineage, earning C for mechanism and D for human claims.17

The mitochondrial-derived peptides humanin, MOTS-c and the SHLP family are preclinical only, with human data limited to observational biomarker correlations rather than any intervention. The IGF-1 and growth-factor group (IGF-1 DES, IGF-1 LR3, MGF, PEG-MGF, HGH Fragment 176-191) is animal-and-in-vitro for anabolism and D for human physique claims. Even where a compound reached humans, the result is often a warning rather than an endorsement: the fat-targeting peptidomimetic adipotide produced dramatic weight loss in obese monkeys but its only human oncology trial was terminated at four patients with no results,16 and the NNMT inhibitor 5-Amino-1MQ has zero human trials despite its longevity marketing.15

How is the encyclopedia organized by class?

Beyond the A-to-Z list, every entry is cross-grouped by mechanism so you can compare like with like. The major families are GLP-1 and incretin agonists; the amylin and calcitonin family; growth-hormone secretagogues split into GHRH analogs (sermorelin, tesamorelin, the CJC-1295 variants) and GHRP ghrelin-receptor agonists (GHRP-2, GHRP-6, hexarelin, ipamorelin); the IGF-1 and growth-factor group; bone-anabolic PTH and PTHrP analogs; the melanocortins; the thymic and immune peptides; the Khavinson bioregulators; the mitochondrial-derived and longevity peptides; the tissue-repair and regenerative peptides; the cosmetic matrikines and topical neuromodulators; the reproductive and neuroendocrine peptides; the nootropic neuropeptides; and smaller clusters for antimicrobial, gut-barrier, antioxidant, and vasoactive peptides.

A separate group flags the non-peptide compounds included for completeness — 5-Amino-1MQ, MK-677, orforglipron, tesofensine,20 SLU-PP-332, pentosan polysulfate, and the biological mixtures actovegin and cerebrolysin — so no reader mistakes a small molecule or an extract for a defined peptide. The class view is where the evidence gradient becomes vivid: an entire tier of FDA-approved Grade-A agents sits alongside families where every human claim is still Grade C or D.

Bottom line. Use this index as a map, not a menu. It tells you what exists, what class it belongs to, and how strong the human evidence is — then hands you to a full monograph for the detail. The single most useful habit it encourages is the one it is built on: never confuse a compelling animal study, or a confident marketing page, with a completed human trial. Evidence grades reflect the best-supported indication per compound and are current as of June 2026; re-verify any regulatory or trial status before relying on it.