Peptide glossary
Reviewed 22 October 2026 · How we research
- Agonist
- A molecule that activates a receptor. Semaglutide is a GLP-1 receptor agonist.
- Bacteriostatic water
- Sterile water with 0.9% benzyl alcohol, used to reconstitute peptides for multi-use vials. See our guide.
- COA (certificate of analysis)
- A lab report showing a batch's purity and identity. See how to read a COA.
- DAC (Drug Affinity Complex)
- A chemical linker that binds a peptide to albumin in the blood, greatly extending half-life — as in CJC-1295 with DAC.
- GHRH
- Growth-hormone-releasing hormone, made by the hypothalamus. Tesamorelin and CJC-1295 are GHRH analogues.
- GHS (growth hormone secretagogue)
- A compound that triggers growth-hormone release via the ghrelin receptor, such as ipamorelin.
- GIP
- Glucose-dependent insulinotropic polypeptide, a gut hormone targeted by tirzepatide and retatrutide.
- GLP-1
- Glucagon-like peptide-1, a gut hormone that increases insulin release and reduces appetite.
- Half-life
- The time it takes for the amount of a substance in the body to fall by half.
- HPLC
- High-performance liquid chromatography: a lab method that separates a sample to measure purity.
- Lyophilised
- Freeze-dried. Peptides are supplied as lyophilised powder because it is far more stable than solution.
- Mass spectrometry (MS)
- A lab method that measures molecular weight, used to confirm a peptide's identity.
- MHRA
- Medicines and Healthcare products Regulatory Agency — the UK medicines regulator.
- Peptide
- A short chain of amino acids, typically fewer than about 50.
- Reconstitution
- Dissolving a lyophilised peptide in a liquid such as bacteriostatic water. See the guide.
- Research use only (RUO)
- A label meaning a product is sold for laboratory research and not for human or veterinary use.
- Subcutaneous
- Into the fatty layer beneath the skin; the route used for most peptide medicines.
- U-100 syringe
- An insulin-style syringe where 100 units = 1 mL. See syringe units.
- WADA
- World Anti-Doping Agency, which publishes the list of substances prohibited in sport.