Peptide Glossary
Key terms and definitions for peptide therapy, FDA regulation, and compounding. 22 terms defined.
5
- 503A Pharmacy
- A compounding pharmacy that operates under Section 503A of the Federal Food, Drug, and Cosmetic Act. These pharmacies compound medications based on individual patient prescriptions from licensed practitioners. Most peptide therapy is dispensed through 503A pharmacies.Clinic Directory →
- 503B Outsourcing Facility
- A compounding facility registered with the FDA under Section 503B. Unlike 503A pharmacies, 503B facilities can compound without individual prescriptions and distribute to healthcare facilities. Subject to more FDA oversight including cGMP requirements.
B
- Bacteriostatic Water
- Sterile water containing 0.9% benzyl alcohol as a preservative. Used to reconstitute lyophilized (freeze-dried) peptide powders for injection. The preservative allows multi-dose use from a single vial, typically for up to 28 days when refrigerated.
- Bioavailability
- The proportion of a substance that enters systemic circulation and is available for biological activity. Injectable peptides have near-100% bioavailability, while oral peptides may have significantly lower bioavailability due to GI degradation.
- BPC
- Body Protection Compound. Refers to a family of peptides derived from a protein found in human gastric juice. BPC-157 is the most studied member, a 15-amino acid synthetic fragment.BPC-157 Profile →
C
- Category 1
- FDA classification for bulk drug substances that may be used in compounding by 503A pharmacies. Category 1 compounds have been evaluated and are considered appropriate for compounding with a prescription. Reclassified in February 2026.FDA Tracker →
- Category 2
- FDA classification for bulk drug substances with 'significant safety risks' that cannot be compounded by 503A pharmacies. In April 2026, 12 peptides were removed from Category 2 and referred to PCAC for review.FDA Tracker →
- cGMP
- Current Good Manufacturing Practice. FDA regulations ensuring pharmaceutical products are consistently produced and controlled according to quality standards. 503B outsourcing facilities must follow cGMP; 503A pharmacies follow USP standards instead.
- COA
- Certificate of Analysis. A document from an analytical laboratory verifying the identity, purity, and potency of a peptide batch. A legitimate COA includes the lab name, batch number, test methods (typically HPLC and MS), and purity percentage.How to Read a COA →
- Compounding
- The practice of creating customized medications by combining, mixing, or altering ingredients to meet individual patient needs. Peptide compounding typically involves reconstituting bulk drug substances into injectable, oral, or topical formulations.
G
- GH Secretagogue
- A substance that stimulates the pituitary gland to release growth hormone. Includes GHRH analogs (CJC-1295, Sermorelin) and ghrelin mimetics (Ipamorelin, GHRP-6). Different from exogenous HGH, which replaces rather than stimulates.CJC-1295 Profile →
- GHRH
- Growth Hormone-Releasing Hormone. A hypothalamic peptide that stimulates the anterior pituitary to release growth hormone. CJC-1295 and Sermorelin are synthetic GHRH analogs.
- GLP-1
- Glucagon-Like Peptide-1. An incretin hormone that stimulates insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite. Semaglutide, tirzepatide, and liraglutide are GLP-1 receptor agonists.GLP-1 Comparison →
H
- Half-Life
- The time it takes for the concentration of a peptide in the body to decrease by half. Short half-life peptides (minutes) require frequent dosing or depot formulations. DAC (Drug Affinity Complex) technology extends half-life by binding to albumin.
- HPLC
- High-Performance Liquid Chromatography. The primary analytical method used to determine peptide purity. A COA should show HPLC purity ≥98% for research-grade and ≥99% for pharmaceutical-grade peptides.
L
- Lyophilized
- Freeze-dried. Most peptides are sold in lyophilized (powder) form for stability during shipping and storage. Must be reconstituted with bacteriostatic water before injection.
M
- MC4R
- Melanocortin 4 Receptor. A receptor in the hypothalamus involved in appetite regulation, energy homeostasis, and sexual function. Targeted by setmelanotide (obesity) and PT-141/bremelanotide (sexual dysfunction).
P
- PCAC
- Pharmacy Compounding Advisory Committee. An FDA advisory committee that reviews bulk drug substances for potential inclusion on the 503A compounding list. The July 23-24, 2026 PCAC meeting will review BPC-157, TB-500, Semax, and other peptides.PCAC Article →
- Peptide
- A short chain of amino acids (typically 2-50) linked by peptide bonds. Smaller than proteins but larger than individual amino acids. Peptides act as signaling molecules, hormones, and neurotransmitters throughout the body.Peptide Database →
R
- Reconstitution
- The process of dissolving a lyophilized (freeze-dried) peptide powder in bacteriostatic water to create an injectable solution. Proper reconstitution technique (gentle swirling, not shaking) is critical for maintaining peptide integrity.
S
- Subcutaneous Injection
- An injection into the fatty tissue layer between the skin and muscle. The most common administration route for peptide therapy. Typical injection sites include the abdomen, thigh, and upper arm. Uses insulin-type syringes (29-31 gauge).Safety Guide →
T
- Trust Score
- TruPeptide's proprietary scoring system for vendors and clinics, calculated from COA availability, third-party lab testing, community reputation, and operational transparency. Scores range from 0-100. No entity can pay to improve their score.Vendor Directory →
This glossary is for educational purposes only. Definitions are simplified for accessibility and may not capture all nuances. Always consult a qualified healthcare professional or regulatory expert for clinical or legal decisions.