Peptide Research Glossary

A peptide is a short chain of 2 to 50 amino acids linked by peptide bonds.

A protein is a large biomolecule composed of 50 or more amino acids folded into a specific three-dimensional structure.

Amino acids are the 20 standard organic molecules that serve as the building blocks of peptides and proteins.

A peptide bond is the covalent chemical bond formed between the carboxyl group of one amino acid and the amine group of another, releasing a water molecule in the process.

Lyophilized refers to the freeze-dried powder form of a peptide.

Also: freeze-dried

Lyophilization is the freeze-drying process used to remove water from a peptide solution under vacuum at low temperatures.

Reconstitution is the process of adding a sterile diluent — most commonly bacteriostatic water — to a lyophilized peptide powder to create an injectable solution.

A research peptide is a peptide compound sold legally for laboratory and scientific use only, not for human consumption.

A peptide stack is a combination of two or more research peptides used together in a protocol to study potential synergistic effects.

Bioavailability is the fraction of an administered dose that reaches systemic circulation in active form.

A milligram is a unit of mass equal to one-thousandth of a gram (1 mg = 1,000 mcg).

Also: mg

A microgram is a unit of mass equal to one-millionth of a gram (1 mcg = 0.001 mg).

Also: mcg, μg

A milliliter is a unit of liquid volume equal to one-thousandth of a liter.

Also: mL

An International Unit (IU) is a measure of biological activity rather than mass.

Also: IU

Concentration is the mass of peptide per unit volume of solution, expressed as mcg/mL.

A syringe unit is a calibration mark on an insulin syringe barrel.

A U-100 syringe is an insulin syringe calibrated at 100 units per milliliter, where 1 unit equals 0.01 mL.

A U-40 syringe is an insulin syringe calibrated at 40 units per milliliter, where 1 unit equals 0.025 mL.

Subcutaneous injection delivers a peptide into the fatty tissue just beneath the skin.

Also: subQ, subcutaneous injection

Intramuscular injection delivers a compound directly into muscle tissue.

Also: IM

Intranasal administration delivers a peptide through the nasal mucosa, bypassing first-pass liver metabolism.

An oral peptide is a peptide administered by mouth.

An injection site is the anatomical location where a peptide is administered.

Needle gauge is a measure of needle thickness; higher gauge numbers indicate thinner needles.

Half-life is the time required for the concentration of a peptide to decrease by 50%.

A peptide cycle is a structured on/off protocol, typically 4–12 weeks on followed by 2–4 weeks off.

Peptide hydrolysis is the breakdown of peptide bonds by water molecules, causing peptide degradation over time.

GHRH is an endogenous hypothalamic peptide that stimulates the pituitary gland to release growth hormone.

Also: Growth Hormone Releasing Hormone

GHRPs are synthetic peptides that stimulate growth hormone release by activating the ghrelin receptor.

Also: Growth Hormone Releasing Peptide

GLP-1 is an endogenous gut-derived incretin hormone that stimulates insulin secretion in response to food intake.

Also: Glucagon-Like Peptide-1

Melanocortins are a family of neuropeptides that regulate pigmentation, appetite, sexual function, and inflammation through melanocortin receptors.

IGF-1 is a liver-produced peptide hormone that mediates most of the anabolic effects of growth hormone.

Also: Insulin-Like Growth Factor 1

Preclinical research is conducted in cell cultures or animal models before any human trials.

A clinical trial is a controlled research study conducted in human participants.

In vitro refers to research conducted outside a living organism, in a test tube or cell culture environment.

Also: in vitro

In vivo refers to research conducted in a living organism, either animal or human.

Also: in vivo

FDA-approved means a compound has been cleared by the US Food and Drug Administration for a specific clinical use based on completed clinical trials demonstrating safety and efficacy.

Bacteriostatic water is sterile water containing 0.9% benzyl alcohol as a preservative.

Also: BAC water, BAC Water

Sterile water for injection is highly purified, sterile water without any preservative.

Lyophilized peptide powder should be stored away from light and moisture.

Reconstituted peptide (in solution) must be refrigerated at 2–8°C and used within 28–30 days.

BPC-157 is a 15-amino-acid synthetic peptide derived from a protective protein in human gastric juice.

Also: BPC157, Body Protection Compound

TB-500 is a 43-amino-acid synthetic fragment of Thymosin Beta-4, a naturally occurring protein involved in cell migration, angiogenesis, and tissue repair.

Also: TB500, Thymosin Beta-4 Fragment

CJC-1295 is a synthetic 30-amino-acid GHRH analogue.

Also: CJC1295

Ipamorelin is a pentapeptide GHRP that selectively stimulates growth hormone release without significant cortisol or prolactin elevation.

Semaglutide is a GLP-1 receptor agonist approved by the FDA as Ozempic (type 2 diabetes) and Wegovy (obesity).

Also: Ozempic, Wegovy

Tirzepatide is a dual GIP/GLP-1 receptor agonist approved by the FDA as Mounjaro (type 2 diabetes) and Zepbound (obesity).

Also: Mounjaro, Zepbound

HGH is a 191-amino-acid protein hormone produced by the pituitary gland that drives growth and metabolism.

Also: Human Growth Hormone, somatotropin

NAD+ is a coenzyme found in all living cells that plays a central role in cellular energy metabolism.

Also: NAD+, nicotinamide adenine dinucleotide

A receptor is a protein — on the cell surface or inside the cell — that a peptide binds to in order to trigger a biological effect.

An agonist is a compound that binds to a receptor and activates it, producing a biological response.

An antagonist is a compound that binds to a receptor without activating it, blocking the binding of natural ligands or agonists.

Pharmacological half-life is the time for plasma drug concentration to decrease by 50%.

Peak concentration (Cmax) is the maximum drug concentration reached in the blood following a dose.

Also: Cmax

Trough concentration (Cmin) is the lowest drug concentration in the blood, occurring just before the next scheduled dose.

Also: Cmin