Peptide glossary

Compounds and mechanism

Agonist — a molecule that binds a receptor and activates it. Selectivity — how narrowly a molecule binds one receptor rather than several in the same family; low selectivity is the usual explanation for effects outside the intended one. Analogue — a synthetic molecule modelled on a natural one, usually altered to change duration or potency. Secretagogue — a compound that prompts a gland to release a hormone rather than supplying the hormone itself.

Half-life — the time for circulating concentration to fall by half, which is what dictates whether a schedule is daily or weekly. Pulsatile — released in bursts rather than continuously, the pattern natural growth hormone secretion follows.

Documentation and testing

COA (certificate of analysis) — the document recording what was measured in a specific production lot. Lot / batch — one production run, tested as a unit; certificates describe one lot and do not transfer between them. HPLC — chromatography separating a sample into components and reporting their proportions; the source of a purity percentage. Mass spectrometry — measurement of mass-to-charge ratio, used to confirm identity against a theoretical molecular weight.

Purity — the main peak as a share of total detected area under a stated method; not a measure of identity, content or sterility. Endotoxin — bacterial cell-wall material relevant to injectable presentations, tested separately from sterility.

Format and logistics

Lyophilised — freeze-dried to a stable powder, the form a vial is supplied in. Reconstitution — dissolving that powder in bacteriostatic water before use. Bacteriostatic water — water containing a preservative, specified for multi-dose vials that are punctured repeatedly. Cold chain — unbroken temperature-controlled handling from fill to fridge. Temperature excursion — any period outside the specified storage range.

Regulatory

Marketing authorisation — regulatory approval of a specific product at a specific strength for a specific indication, on the basis of a completed trial programme. Investigational — in active clinical development, not authorised. Research use only — supplied for laboratory purposes, not for administration to people. WADA — the World Anti-Doping Agency, whose prohibited list covers most compounds in this category at all times, in and out of competition.