Peptide Words Explained: A Plain-English Glossary
These are words you may see on labels, lab reports and websites. For the bigger picture, read Peptides 101.
Basics
Amino acid: A small building block. The body joins amino acids together to make proteins.
Peptide: A short chain of amino acids linked together, usually about 2 to 50. Some peptides are approved medicines. Many products sold online are not.
Protein: A larger molecule made from one or more long chains of amino acids. Under FDA rules, a chain of more than 40 amino acids counts as a protein.
Clinical trial: A research study done in people. Trials happen in steps called phases, to learn whether a treatment is safe and whether it works.
Rules and product types
FDA: The U.S. Food and Drug Administration. It's the federal agency that reviews and approves medicines.
FDA-approved: The FDA reviewed the maker's test data. It decided the drug's benefits outweigh its known risks for the people it's meant for. You can look up approved drugs in Drugs@FDA.
Prescription drug: A medicine a doctor prescribes for one person, bought at a pharmacy.
Compounded drug: A drug mixed or made by a pharmacy or outsourcing facility, often for a patient whose needs an approved drug can't meet. Compounded drugs are not FDA-approved. The FDA doesn't check their safety, effectiveness or quality before they're sold.
503A: The part of federal law for compounding by a licensed pharmacist in a state-licensed pharmacy, or by a licensed doctor. The drug must be made for a specific patient with a valid prescription.
503B (outsourcing facility): The part of federal law for compounding in an outsourcing facility that registers with the FDA. These facilities are inspected by the FDA and must follow stricter manufacturing rules. They may make drugs with or without a prescription for a specific patient.
CGMP: Short for "current good manufacturing practice." These are the FDA's quality rules for making drugs. 503B facilities must follow them. 503A pharmacies don't have to.
Research use only (RUO): A label saying a product is only for lab research, not for use in people. (In FDA rules, the formal "For Research Use Only" label is for lab test products still in development.) The FDA has warned companies that sold products falsely labeled "for research purposes" or "not for human consumption" to people, with dosing instructions. It urges consumers not to buy these products, which are of unknown quality and may be harmful.
Not for human consumption: A similar label saying a product is not meant for people. The FDA has said this label was false on some products sold online.
Counterfeit: A fake product made to look real. The FDA warns that counterfeits may have the wrong ingredient, or too much, too little or none of the right one.
Testing and lab reports
Certificate of analysis (COA): A lab's report on one sample it tested. See how to check a COA.
Third-party testing: Testing by an outside lab, not by the company selling the product. See our list of testing labs.
Batch or lot: A group of products made together. A batch or lot number ties a product to its lab report. A COA only applies to the batch that was tested.
HPLC: Short for "high-performance liquid chromatography." A lab method that separates a sample into its parts. It's often used to measure purity.
Mass spectrometry (MS or LC-MS): A lab method that measures the weight of molecules. It's used to confirm a sample's identity.
Chromatogram: The graph an HPLC test makes. Each peak stands for something in the sample.
Purity: How much of the material in the sample is the expected compound, often shown as a percentage. High purity alone doesn't prove which compound it is.
Identity: Whether the expected compound is actually there. This usually needs mass spectrometry.
Net peptide content: How much of a sample's weight is the peptide itself, not counting water and certain other substances.
Endotoxin: A substance from the outer layer of certain bacteria. It can cause fever if it gets into the body. Labs can test for it.
Lyophilized: Freeze-dried. The product is frozen, then the water is removed under a vacuum, leaving a dry powder or "cake."
ISO/IEC 17025: An international standard for how competent testing labs are. A lab that's accredited to it is only covered for the specific tests listed in its "scope."
Accreditation scope: The official list of tests a lab is accredited to do. Check it with the group that accredited the lab.
Safety words
Adverse event: A bad or unwanted health effect that happens while using a medicine or product.
MedWatch: The FDA's program for reporting side effects and quality problems. Anyone can report a problem.
Immunogenicity: The chance that the body's immune system reacts to a product or its impurities. The FDA has flagged this risk for several peptides.