Reference

Glossary

The words the guides cannot avoid using, in plain English. Every compound in the archive is here too, with the names it is also sold under, so a term you met somewhere else resolves to the entry that covers it.

93 entries. Definitions describe words, not products: nothing here tells you what to take or how much.

Afamelanotide (MT-1)also Melanotan I, Scenesse, NDP-MSH: The melanocortin agonist that completed development. Approved for a rare light-sensitivity disorder, and the direct counterexample to melanotan II.; Afamelanotide guide
Agonist: Something that switches a receptor on. A receptor is a lock on the surface of a cell, and an agonist is a key that turns it. Most peptides discussed here work by being a key for a lock the body already has.
Analoguealso analog: A lab-made copy of a natural molecule, changed on purpose. Usually the change is to make it last longer in the body, since the natural version is often broken down within minutes.
Animal study (study design): A study design label used on every citation in this archive, so the kind of evidence behind a claim is visible before you read it.
Antagonist: The opposite of an agonist. It sits in the lock without turning it, so the real key cannot get in. Used to block a signal rather than send one.
AOD-9604also hGH fragment 176-191, Lipotropin fragment: A growth hormone fragment that completed a phase 2b obesity trial and did not beat placebo. One of the few entries here with a proper negative result.; AOD-9604 guide
Bacteriostatic wateralso BAC water: Sterile water containing a preservative that stops bacteria multiplying, used to dissolve freeze-dried powder. Different from plain sterile water, which has no preservative.
Bioavailability: How much of what you take actually reaches your bloodstream in usable form. It is why a peptide that works in a lab dish may do nothing when swallowed: digestion breaks it apart first.
Biomarker: Something measurable in the body, like a blood level, used as a stand-in for an outcome. Moving a biomarker is not the same as helping anyone, and the gap between the two is where a lot of claims live.
Blendalso stack: Several peptides sold pre-mixed in one vial under a marketing name. The name is the seller's, nobody standardises what goes in it, and a blend does not inherit its ingredients' evidence as a combination.; Named blends
BPC-157also Body Protection Compound 157, PL 14736, Pentadecapeptide BPC 157: A 15-amino-acid sequence with a large, remarkably consistent animal literature, almost all of it from a small affiliated research network, and no completed human trial reporting results.; BPC-157 guide
Bremelanotide (PT-141)also PT-141: A melanocortin agonist approved for hypoactive sexual desire disorder in premenopausal women. Approved on a real but modest effect size, which the discussion around it frequently inflates.; Bremelanotide guide
Cagrilintide (AM833)also AM833, Long-acting amylin analogue: A long-acting amylin analogue, mostly studied in combination with semaglutide. A different satiety pathway to the incretins, which is the point of it.; Cagrilintide guide
Case report / series (study design): A study design label used on every citation in this archive, so the kind of evidence behind a claim is visible before you read it.
Certificate of analysisalso COA: A document stating what a batch contains. A certificate supplied by the seller of that batch is a claim by an interested party, not independent verification.
CJC-1295also Modified GRF (1-29), CJC-1295 DAC, Sermorelin analogue: A GHRH analogue with early human pharmacokinetic data and no efficacy programme. The DAC and non-DAC versions are pharmacologically very different and are constantly conflated.; CJC-1295 guide
ClinicalTrials.gov: The public registry where trials are recorded, usually before they start. Useful in both directions: it shows what is being tested, and it shows when a compound has never been tested in anyone.
Compounding pharmacy: A pharmacy that mixes a preparation for an individual rather than selling a manufactured product. It operates under a different regulatory route from drug approval, and the two get presented as though they were the same.
Concentration: How much substance sits in a given volume of liquid, for example milligrams per millilitre. It is set by how much liquid you added, not by what is in the vial.
Contested (evidence grade): Good human trials exist and they disagree with each other. That is not the same as unproven. The evidence is real, it just points both ways, and sensible people read it differently.; How grades are applied
DOI: A permanent identifier for a published document. Unlike a web address it is not supposed to break, which is why a real citation carries one.
Double-blind: Neither the participants nor the researchers know who is getting the real treatment until the trial ends. This stops expectations shaping both what people report and how it is measured.
DSIPalso Delta sleep-inducing peptide: Named for an effect that later work struggled to reproduce. A nine-amino-acid peptide with fifty years of inconsistent literature and no established receptor.; DSIP guide
Early clinical (evidence grade): It has been tried in people, but only in small or early studies. Enough to show it does something in the body. Not enough to show that something actually helps.; How grades are applied
Elamipretide (SS-31)also SS-31, MTP-131, Bendavia: A cardiolipin-binding peptide with real phase 3 programmes and a mixed record. Genuinely contested rather than merely unproven.; Elamipretide guide
Endpoint: The thing a trial measured to decide whether it worked, chosen before it started. A trial that misses its main endpoint but reports something else that improved has not shown what it set out to show.
Epitalonalso Epithalon, AEDG peptide, Ala-Glu-Asp-Gly: A four-amino-acid peptide carrying extraordinary longevity claims on an evidence base that is almost entirely one research group.; Epitalon guide
Established (evidence grade): Big, properly run human trials back this up, or a regulator has approved it. The open questions are how well it works and how long that lasts, not whether it does anything at all.; How grades are applied
Follistatin-344 (FS-344)also FS-344, Myostatin inhibitor: A myostatin-binding protein with dramatic animal results and essentially no human data for the administered protein. The gap between the two is the whole story.; Follistatin-344 guide
GHK-Cualso Copper peptide, Glycyl-L-histidyl-L-lysine copper: A copper-binding tripeptide with extensive in vitro data and modest topical cosmetic evidence. The gap between the gene-expression literature and what topical application does is very wide.; GHK-Cu guide
GHRP-2also Pralmorelin, KP-102, GPA-748: A ghrelin receptor agonist with real human pharmacology behind it, approved in Japan as a diagnostic agent, and zero registered trials for anything people actually use it for.; GHRP-2 guide
GHRP-6also Growth hormone releasing peptide 6, SKF-110679: An early growth hormone secretagogue, notable mostly for producing intense hunger and for raising cortisol and prolactin alongside GH.; GHRP-6 guide
Glutathionealso GSH, L-glutathione, reduced glutathione: The body's main intracellular antioxidant, sold widely as an injectable and oral skin-lightening agent. The biology is not in question. The cosmetic claim rests on small trials, and the injectable route on none.; Glutathione guide
Gonadorelinalso GnRH, LHRH, Luteinizing hormone-releasing hormone, Factrel: The native GnRH decapeptide. An established diagnostic and fertility agent whose popular use, restarting suppressed testosterone production, is the use with the least evidence behind it.; Gonadorelin guide
Half-life: How long it takes for half of a dose to clear your body. It is not the same as how long the effect lasts, and treating the two as equal is one of the commonest errors in peptide discussion.
Hexarelinalso Examorelin, EP-23905: A potent GH secretagogue with pronounced tachyphylaxis and a separate cardiac literature that is more interesting than its GH effects.; Hexarelin guide
Humaninalso HN, MT-RNR2, Rattin: A peptide encoded in mitochondrial DNA, of real scientific interest as a signalling molecule, with no interventional human trial of it as a therapy.; Humanin guide
IGF-1 LR3also Long R3 IGF-1, Mecasermin analogue (unapproved): A cell-culture reagent, engineered to evade the binding proteins that regulate IGF-1 in the body. That modification is exactly why it should not be administered to people.; IGF-1 LR3 guide
In vitro: Done in a dish, with cells or tissue rather than a living body. In vitro results are a reason to investigate something, never evidence that it works in a person.
In vivo: Done in a living organism, which may be an animal or a human. Saying something works in vivo means little until you say which.
Indication: The specific condition a medicine is officially approved to treat. Approved for one indication does not mean approved generally, and that gap is where most misleading claims sit.
Ipamorelinalso NNC 26-0161: A selective growth hormone secretagogue that reached phase II for postoperative ileus and was discontinued after missing its endpoints. A useful case study in what a negative trial looks like.; Ipamorelin guide
Kisspeptin-10 (KP-10)also Metastin 45-54, KP-10: The upstream trigger of the reproductive axis, with genuine ongoing academic human research. One of the more scientifically respectable entries at this end of the ladder.; Kisspeptin-10 guide
KPValso Lys-Pro-Val, alpha-MSH(11-13): The three-residue anti-inflammatory tail of alpha-MSH, with consistent preclinical gut and skin data and no completed human trial.; KPV guide
Liraglutidealso Victoza, Saxenda, GLP-1 receptor agonist: The daily GLP-1 agonist that came before the weekly ones. Smaller effect, longer real-world record, and a completed cardiovascular outcomes trial.; Liraglutide guide
LL-37also Cathelicidin, hCAP-18, CAMP: The only human cathelicidin, with a very large basic-science literature and a small clinical one. Its dual role, antimicrobial and immunomodulatory, is also why its effects are hard to predict.; LL-37 guide
Lyophilisedalso lyophilized, freeze-dried: Freeze-dried into a stable powder, which is how most peptides are shipped because they keep far longer dry than in liquid.
Mazdutidealso IBI362, LY3305677: An oxyntomodulin analogue developed primarily in China, further along the regulatory path there than anywhere else. Its approval status is the thing people most often get wrong about it.; Mazdutide guide
Mechanistic only (evidence grade): Lab-dish work and theory. There is a reason to think it might work, and that is all there is. This is the bottom of the ladder.; How grades are applied
Melanotan II (MT-2)also MT-II, MT2: A non-selective melanocortin agonist with a documented adverse event record including case reports of changing and new melanocytic lesions. Included as a catalogue entry precisely because of that record.; Melanotan II guide
Meta-analysis: A study that pools the results of earlier studies. It inherits the quality of what went into it, so pooling weak trials produces a precise-looking number built on imprecise inputs.
MOTS-calso Mitochondrial ORF of the 12S rRNA type-c: A mitochondrial-derived peptide with interesting metabolic biology in mice and essentially no human interventional data. Currently a research finding, not a therapy.; MOTS-c guide
NAD+also nicotinamide adenine dinucleotide, NAD, NR, NMN, nicotinamide riboside, nicotinamide mononucleotide: An essential coenzyme in every cell, sold as an IV drip and as oral precursors for ageing. The precursors demonstrably raise blood NAD+. Whether raising it does anything for a person is a separate question with much thinner answers.; NAD+ guide
Observational (study design): A study design label used on every citation in this archive, so the kind of evidence behind a claim is visible before you read it.
Observational study: Research that watches what happens without assigning treatment. It can show that two things occur together and cannot show that one caused the other.
Off-label: Prescribing an approved medicine for something it was not approved for. Legal for a clinician and common in practice, but it means the evidence a regulator reviewed was about a different use.
Open-label: Everyone knows who is getting what. Easier to run and much easier to bias, so an open-label result is weaker than a blinded one even when the effect looks large.
Open-label trial (study design): A study design label used on every citation in this archive, so the kind of evidence behind a claim is visible before you read it.
Orphan designation: A status given to treatments for rare conditions to make developing them viable. It is an incentive, not a finding that the treatment works.
Oxytocinalso Pitocin, Syntocinon: An approved obstetric drug with a very large literature, and a second life as a social and behavioural intervention where the evidence is far weaker than the popular account of it.; Oxytocin guide
Placebo-controlled: A trial where the comparison group gets a dummy treatment. It matters because people improve for all sorts of reasons, and without a placebo arm you cannot tell those reasons from the drug.
PMID: The ID number PubMed gives a paper. A citation with a PMID points at one specific record you can open; a citation without one asks you to go searching and take the claim on trust.
Preclinical: Everything before human testing: lab dishes and animals. A large preclinical literature is not a substitute for one human trial, and results in animals frequently fail to repeat in people.
Preclinical (evidence grade): Tested in animals or cells, never finished in people. Results in animals often fail to repeat in humans, and being safe in an animal does not mean being safe in a person.; How grades are applied
Preprint: A paper posted publicly before peer review. Not worthless, but it has not yet been checked by anyone other than its authors.
Publication bias: The tendency for studies that found something to get published while studies that found nothing do not. It makes a body of evidence look more positive than the research actually was.
Pulsatile: Released in bursts rather than at a steady level. Some hormones only work properly in bursts, and the same molecule given continuously can produce the opposite effect. Teriparatide is the textbook case.; Teriparatide
Randomised controlled trialalso RCT, randomized controlled trial: The strongest common study design. People are split into groups by chance, one group gets the treatment and another does not, so differences between the groups are less likely to be explained by who ended up where.
Receptor: A structure on or in a cell that a signalling molecule binds to. Binding is what passes the message. Which receptors a compound binds, and how selectively, explains most of both its effects and its side effects.
Reconstitution: Adding liquid to a freeze-dried powder to dissolve it. How much liquid you add sets the concentration, which is the arithmetic the calculator on this site does and the only thing it does.; Reconstitution calculator
Replication: When an independent group repeats a study and gets the same result. A literature where every paper comes from one group has consistency without replication, and those are not the same thing.
Research use onlyalso RUO, research chemical: A label that limits the seller's legal exposure. It is not a quality grade, not a purity standard and not a safety claim, and material sold this way is not made to the standards medicines are.
Retatrutidealso LY3437943, Triple agonist, GGG agonist: A triple incretin agonist with phase 2 obesity results larger than anything before it, and no completed phase 3. The most interesting unfinished story in the class.; Retatrutide guide
Review (study design): A study design label used on every citation in this archive, so the kind of evidence behind a claim is visible before you read it.
Secretagogue: Something that makes your body release more of a hormone it already produces, rather than supplying that hormone from outside. The distinction matters because your own feedback controls stay in play.
Selankalso TP-7, Tuftsin analogue: A Russian-registered anxiolytic peptide with the same appraisal problem as Semax: a real literature that is largely inaccessible to outside review.; Selank guide
Selectivity: How precisely something hits only its intended target. A selective compound acts on one receptor; a non-selective one hits several, which is where unintended effects usually come from.
Semaglutidealso GLP-1 receptor agonist, Ozempic, Wegovy, Rybelsus: A long-acting GLP-1 receptor agonist with large phase III programmes in type 2 diabetes, obesity, and cardiovascular outcomes. One of the few entries here where the evidence base is genuinely deep.; Semaglutide guide
Semaxalso ACTH (4-10) analogue, Met-Glu-His-Phe-Pro-Gly-Pro: An ACTH(4-10) analogue approved in Russia for stroke and cognitive indications, with a literature that is largely Russian-language and difficult to appraise from outside.; Semax guide
Sermorelinalso GHRH(1-29), Geref, GRF 1-29: The shortest active GHRH fragment. Once approved, withdrawn commercially rather than for safety, and now mostly encountered as a compounded preparation.; Sermorelin guide
Setmelanotide (RM-493)also Imcivree, RM-493: An MC4R agonist approved only for a handful of rare genetic obesity syndromes. A clean example of a real drug with a genuinely tiny eligible population.; Setmelanotide guide
Survodutidealso BI 456906, BI456906: A dual glucagon/GLP-1 agonist in phase 3 for obesity and for MASH. Real trials, real sponsor, no approval anywhere yet, and the phase 3 readouts that matter are not published.; Survodutide guide
Systematic review: A review that searches the literature by a stated method so somebody else could repeat the search. Different from a narrative review, where the author simply picks what to discuss.
Tachyphylaxis: When a drug stops working as well because you keep taking it. The body adapts and the response fades, so the same dose does less over weeks.
Teduglutidealso GLP-2 analogue, Gattex, Revestive: A GLP-2 analogue approved for short bowel syndrome. A useful example of a peptide with a narrow, well-defined indication and a correspondingly narrow evidence base.; Teduglutide guide
Teriparatide (PTH(1-34))also PTH(1-34), Forteo, Forsteo: A parathyroid hormone fragment approved for severe osteoporosis. The clearest case in this catalogue of a hormone whose effect reverses depending on how it is administered.; Teriparatide guide
Tesamorelinalso TH9507, Egrifta, GHRH analogue: A GHRH analogue approved specifically for HIV-associated lipodystrophy. Frequently cited well outside that indication, on evidence that does not extend there.; Tesamorelin guide
Thymalinalso Thymus extract, Timalin: Not a defined molecule but a thymic extract, with a clinical literature that is almost entirely from one national research tradition and essentially no presence in the international trial registry.; Thymalin guide
Thymosin Alpha-1 (TA-1)also Tα1, Zadaxin, Thymalfasin: An immunomodulatory peptide approved in some countries for hepatitis B and studied in sepsis and oncology. Genuinely contested: real trials exist and they disagree.; Thymosin Alpha-1 guide
Thymosin Beta-4 (TB-500)also TB-500, Tβ4, RGN-259: A naturally occurring actin-binding peptide with genuine early clinical work in eye and wound indications. "TB-500" as sold is usually a fragment, not the full peptide, and the two are routinely conflated.; Thymosin Beta-4 guide
Tirzepatidealso GIP/GLP-1 dual agonist, Mounjaro, Zepbound: A dual incretin agonist hitting both GIP and GLP-1 receptors. Phase III results in diabetes and obesity are larger than single-agonist comparators; the mechanistic reason is still argued.; Tirzepatide guide
Vasoactive Intestinal Peptidealso VIP, Aviptadil, RLF-100: A well characterised endogenous neuropeptide with an enormous basic literature, and a clinical history dominated by one contested and heavily publicised COVID-19 programme.; Vasoactive Intestinal Peptide guide
WADA: The World Anti-Doping Agency, which publishes the list of substances banned in sport. Many compounds in this archive are on it, and that status is independent of whether they are legal to possess.

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