Peptide Glossary
The terms you will meet on peptide labels, COAs and vendor pages, defined in a sentence or two.
Terms A–Z
- Bacteriostatic water
- Sterile water containing 0.9% benzyl alcohol, which inhibits bacterial growth so a vial can be drawn from more than once. Used to reconstitute lyophilized (freeze-dried) peptides. More
- Certificate of analysis (COA)
- A lab report for a specific batch stating identity, purity and sometimes contaminant results. A COA is only meaningful if it names the lab, the batch or lot number and the method. More
- Compounding pharmacy
- A pharmacy that prepares medications for an individual prescription. Under sections 503A and 503B of the FD&C Act, compounded drugs are not FDA-approved, and FDA limits compounding of drugs that are commercially available.
- Endotoxin
- A toxin from the outer membrane of Gram-negative bacteria that can cause fever and inflammation if injected. Endotoxin testing (LAL) is separate from purity testing.
- FDA-approved
- A specific drug product, from a specific manufacturer, that FDA has approved for a labeled indication after reviewing safety and efficacy data. Approval of a brand does not make other products with the same ingredient approved.
- GHRH analog
- A peptide that mimics growth-hormone-releasing hormone and prompts the pituitary to release growth hormone; examples include sermorelin, tesamorelin and CJC-1295. More
- GHRP / ghrelin mimetic
- A peptide that acts on the ghrelin receptor to stimulate growth-hormone release; examples include ipamorelin, GHRP-2 and GHRP-6. More
- GLP-1 receptor agonist
- A drug that activates the GLP-1 receptor, increasing insulin secretion and reducing appetite. Semaglutide and liraglutide are GLP-1 agonists; tirzepatide also acts on GIP receptors and retatrutide on GIP and glucagon receptors. More
- HPLC
- High-performance liquid chromatography: a method that separates a sample's components to estimate purity as a percentage of the main peak.
- Investigational
- A drug being studied in clinical trials that FDA has not approved. Investigational drugs are legally available only through trials or expanded-access programs.
- IU (international unit)
- A unit of biological activity rather than mass, used for some hormones such as hCG and HGH. IU-to-mg conversion differs by substance. More
- Lyophilized
- Freeze-dried. Most peptides are shipped as a lyophilized powder and must be reconstituted with a diluent before use. More
- Mass spectrometry (MS)
- A method that measures molecular mass to confirm a compound's identity. Often paired with HPLC (LC-MS) on a COA.
- PubMed
- The US National Library of Medicine's index of biomedical literature. A PMID is the unique ID of a PubMed record.
- Reconstitution
- Adding a measured volume of diluent to a lyophilized peptide to make a solution of known concentration (mg per mL). More
- Research use only (RUO)
- A label stating a product is not for human or veterinary use. RUO peptides are not FDA-approved drugs and are not made under drug manufacturing standards. More
- Titration
- Starting a medicine at a low dose and increasing it in steps to improve tolerability, as in the semaglutide and tirzepatide labels. More
- U-100 insulin syringe
- A syringe marked in units where 100 units equal 1 mL. Unit markings measure volume, not dose — the dose depends on the solution's concentration. More
- WADA prohibited list
- The World Anti-Doping Agency's list of substances banned in sport. It includes GH secretagogues, BPC-157 and many other peptides.
- Warning letter
- An official FDA notice that a company is violating federal law, for example by selling unapproved new drugs. More