Peptide Glossary
Decoded

The building blocks of peptides and proteins. There are 20 standard amino acids that combine in different sequences to form every peptide and protein in your body.

Relating to the building up of complex molecules in the body, such as muscle tissue. Some peptides are studied for their anabolic properties.

A substance that reduces anxiety. Some peptides, such as Selank and DSIP, are studied for their anxiolytic properties — meaning they may help calm the nervous system without the sedation or dependence associated with traditional anti-anxiety medications. See Selank →

Sterile water containing a small amount of benzyl alcohol (0.9%) that inhibits bacterial growth. It is the standard solvent used to reconstitute lyophilized peptides before injection.

The proportion of a substance that enters the bloodstream and is able to have an active effect. Different administration routes (injection vs. oral) dramatically affect bioavailability.

Body Protection Compound-157, a synthetic pentadecapeptide (15 amino acids) derived from a protective protein found in gastric juice. Widely studied for tissue repair and healing, BPC-157 is currently classified as FDA Banned (Category B), meaning it cannot be compounded for human use. Learn more →

A unique numerical identifier assigned to every chemical substance by the Chemical Abstracts Service. We include CAS numbers in our registry entries for precise identification.

A licensed pharmacy that creates customized medications by mixing ingredients according to a doctor's prescription. Some peptides are available through compounding pharmacies.

An FDA regulatory status indicating that a peptide can legally be prepared by licensed compounding pharmacies under a physician's prescription, even though it may not have full FDA approval as a standalone drug. This is a common status for peptides like Thymosin Alpha-1 and PT-141. See Thymosin Alpha-1 →

A condition or factor that makes a particular treatment inadvisable. Our peptide profiles list known contraindications for each compound.

Describes an effect that changes (usually increases) as the dose of a substance increases.

The ability of a substance to produce a desired therapeutic effect. Clinical trials measure efficacy under controlled conditions.

Originating from within the body. Many therapeutic peptides are synthetic versions of endogenous peptides your body already produces.

A classification system used in our registry to indicate the strength of scientific evidence supporting a peptide's investigated uses. Our scale ranges from 'Extensive Clinical Data' (multiple large clinical trials) through 'Moderate Clinical Data' and 'Early Clinical / Animal Models' down to 'Anecdotal / Theoretical' (limited or no formal research).

Originating from outside the body. When a synthetic peptide is administered, it is an exogenous substance — the counterpart to endogenous (naturally produced). Most therapeutic peptides are exogenous versions of hormones or signaling molecules your body makes on its own.

The U.S. federal agency responsible for approving drugs, biologics, and medical devices. A peptide's FDA status is one of the most important fields in our registry.

A peptide that has completed rigorous clinical trials and received formal FDA approval for specific medical uses. Examples: semaglutide (Ozempic/Wegovy), tirzepatide (Mounjaro/Zepbound), liraglutide (Saxenda).

A gut hormone that, like GLP-1, helps regulate blood sugar and appetite. Tirzepatide (Mounjaro/Zepbound) is a dual GLP-1/GIP receptor agonist, meaning it activates both pathways simultaneously for enhanced metabolic effects. See Tirzepatide →

A naturally occurring incretin hormone that regulates blood sugar, slows gastric emptying, and reduces appetite. GLP-1 receptor agonists like semaglutide and liraglutide are among the most well-known therapeutic peptides, primarily used for type 2 diabetes and weight management. See Semaglutide →

A substance that stimulates the pituitary gland to release growth hormone. Peptides like CJC-1295 and Ipamorelin fall into this category and are often used together ("stacked") to amplify growth hormone pulses. See CJC-1295 →

The time it takes for half of a substance to be eliminated from the body. A peptide's half-life determines how frequently it needs to be administered.

An injection administered directly into a muscle. While subcutaneous injection is more common for peptides, some are administered intramuscularly for faster absorption into the bloodstream.

An injection or infusion delivered directly into a vein, providing the fastest possible absorption (100% bioavailability). Some peptides like Thymosin Alpha-1 can be administered intravenously in clinical settings, though this route is less common for at-home peptide therapy.

Describes a substance that is being studied in clinical trials but has not yet received FDA approval for therapeutic use. An Investigational New Drug (IND) application must be filed with the FDA before human clinical trials can begin.

Studies conducted in a laboratory setting (literally 'in glass'), such as cell cultures. In vitro results don't always translate to effects in living organisms.

Studies conducted in living organisms, including animal models and human clinical trials. In vivo evidence is generally stronger than in vitro.

Freeze-dried. Many peptides are sold in lyophilized (powder) form and must be reconstituted with bacteriostatic water before use.

How a peptide produces its effects in the body at a molecular level. Our registry profiles explain each peptide's mechanism of action in plain language.

The total mass of a molecule, typically measured in Daltons (Da) or grams per mole (g/mol). Molecular weight is displayed on our peptide profile pages and affects how a peptide behaves in the body — smaller peptides generally have better bioavailability and tissue penetration.

A peptide that acts as a signaling molecule in the nervous system. Selank and Semax are examples of neuropeptides studied for cognitive effects. See Selank →

The use of an FDA-approved medication for a purpose other than what it was originally approved for. Off-label prescribing is legal and common but means less clinical data exists for that specific use.

A chain of amino acids linked by peptide bonds, generally ranging from 2 to about 100 amino acids in length. Shorter than proteins, peptides serve as hormones, neurotransmitters, and signaling molecules throughout the body. For example, semaglutide is a 39-amino-acid peptide, while BPC-157 has 15.

The study of how a drug moves through the body — absorption, distribution, metabolism, and excretion (often abbreviated ADME). This determines dosing schedules and optimal administration routes.

The stages of clinical trials required for FDA approval. Phase I tests safety in a small group (20–100 people). Phase II evaluates efficacy and side effects in a larger group (100–300). Phase III confirms results in large, diverse populations (1,000–3,000+). A Phase IV trial may follow after approval to monitor long-term effects.

The process of dissolving a lyophilized (freeze-dried) peptide in a sterile liquid (usually bacteriostatic water) to prepare it for injection. Proper reconstitution technique — gently swirling rather than shaking — is important to preserve the peptide's molecular structure.

A regulatory classification meaning a substance is available for laboratory research but has not been approved for human therapeutic use. Peptides like TB-500 and Selank carry this classification in the U.S. See TB-500 →

An injection administered into the fatty tissue just beneath the skin. This is the most common administration route for peptide therapy.

A peptide manufactured in a laboratory rather than extracted from biological sources. Most therapeutic peptides are synthetic versions of naturally occurring sequences.

The range between an effective dose and a toxic dose. A wide therapeutic index means the substance is relatively safe; a narrow one means careful dosing is critical.

The international organization that maintains the list of substances banned in competitive sports. Several peptides, including growth hormone secretagogues, are WADA-prohibited. Our registry tracks WADA status for every compound.