Glossary

The words that recur across the entries and the guides, defined once and plainly. Grouped by what they are about.

Making it up

Bacteriostatic water: Sterile water with 0.9% benzyl alcohol, which inhibits bacterial growth and keeps a punctured vial usable for weeks. The usual solvent for reconstitution.
Concentration: How much peptide is in each millilitre of the reconstituted solution — the vial amount divided by the solvent added. Calculator.
Lyophilisate: The freeze-dried powder itself. Peptides ship dry because they are far more stable that way than in solution.
Reconstitution: Dissolving the freeze-dried peptide powder in a sterile liquid before use. How it is done.
Sterile water: Water with no preservative. It works as a solvent but, once opened, is intended for a single use.

Half-life: The time for the amount in the body to fall by half. It sets how often a compound is dosed and how long an effect — or an error — lasts.
International Unit (IU): A measure of biological activity, not mass or volume. Some compounds (insulin, hCG, gonadotropins, growth hormone) are dosed in IU, and IU do not convert to milligrams without the figure for the specific product. Units, IU and milligrams.
Milligram (mg) / microgram (mcg): Units of mass. 1 mg = 1000 mcg. Dropping that factor of a thousand is the most common — and silent — dosing error.
Syringe unit: A mark on an insulin syringe barrel: a unit of volume. On a U100 syringe one unit is 0.01 ml of whatever is dissolved in it.

Agonist / antagonist: An agonist switches a receptor on; an antagonist blocks it. The same target reached from opposite directions — a GnRH agonist and antagonist, for instance, are used for different ends.
Endogenous: Occurring naturally in the body. It says nothing about whether a manufactured product containing the substance is safe or legal.
Peptide: A short chain of amino acids — the same building blocks as proteins, in a shorter string. Several compounds on this site are not peptides at all; each says so in its first line.
Receptor: A protein a molecule binds to in order to have an effect. What a compound does is largely a question of which receptors it reaches and whether it turns them on or off.

Certificate of analysis (COA): A laboratory report on a product. A manufacturer's COA on its bulk lot and a reseller's third-party test on one vial are different documents, and the second is what a buyer usually sees. What it proves.
Endotoxin: A fever-causing fragment of bacterial cell wall. It survives sterilisation, matters enormously for anything injected, and is usually not on a seller's test report unless paid for separately.
GMP: Good Manufacturing Practice — the regulated quality system a licensed medicine is made under. Research-chemical peptides are not made or released under it.
HPLC: High-performance liquid chromatography — the standard method for measuring a peptide's purity and identifying it. The core of most test reports. Testing.
Mass spectrometry: Weighs molecules to confirm identity. Purity by HPLC without a mass-spec identity check is an incomplete answer — a high purity figure can belong to the wrong molecule.
Net peptide content: How much of the powder is actually peptide, as opposed to counter-ion (such as residual TFA) and water. Different from, and usually lower than, the HPLC “amount”.
Recombinant: Made by engineered living cells rather than assembled chemically — how most large peptide and protein drugs (insulin, growth hormone) are produced.
Synthetic: Built chemically, most often by solid-phase peptide synthesis — the 1963 invention that made synthetic peptides possible at all. History.

Open-label: A study where everyone knew they got the compound. Improvement in one cannot, by itself, show the compound worked.
Placebo / blinding: A placebo is an inert comparison; blinding keeps participants and assessors from knowing who got what. Together they stop expectation from masquerading as effect.
Randomised controlled trial (RCT): A study that randomly assigns people to the compound or a control, ideally blinded. The strongest evidence that a compound caused an effect. Reading the research.
Retraction: A journal withdrawing a paper for error or misconduct. Retracted studies keep circulating as if they stood — always worth checking a headline result against.
Surrogate endpoint: A lab marker assumed to predict a real outcome — “raises NAD⁺” standing in for “improves health”. The assumption often fails, so the two are different claims.
Systematic review / meta-analysis: A study that gathers and weighs every trial on a question. When recent, the single strongest thing to read.

Approved drug: Authorised as a medicine by a regulator, on the strength of controlled trials. Almost always prescription-only. Legal status.
Compounding (503A / 503B): Preparing a medicine outside mass manufacturing: 503A pharmacies compound for an individual prescription, 503B outsourcing facilities in bulk. Neither produces an FDA-approved product.
Marketing authorisation: The licence a medicine needs before it may be sold in a jurisdiction. A substance meeting the medicine definition without one is an unauthorised medicinal product.
Novel food: The EU regime for an ingestible with no significant food history before May 1997 — it needs pre-market authorisation before it can be sold as a food/supplement.
Off-label: Using an approved drug for a purpose, dose or population it was not approved for. Legal for a doctor to prescribe; common in the grey market without one.
Research chemical: Sold labelled “not for human consumption” to place it outside medicines law. The label rarely works in law once the marketing shows intended human use. Why sellers write it.
Therapeutic Use Exemption (TUE): Permission for an athlete to use an otherwise-prohibited medicine for a genuine medical need. Anti-doping.
WADA Prohibited List: The World Anti-Doping Agency's annual list of substances banned in sport, in categories (S0–S9). Separate from whether a substance is legal. Anti-doping.