RedoseA
Agonist
A molecule that binds a receptor and activates it, producing a biological response. Most weight-loss peptides are receptor agonists, for example GLP-1 agonists.
Amino acid
The building-block molecule of peptides and proteins. Short chains of amino acids linked together form peptides.
AOD-9604
A modified fragment of human growth hormone studied for fat metabolism without the broader growth effects of full hGH.
B
Bacteriostatic water
Sterile water containing 0.9% benzyl alcohol, which inhibits bacterial growth. It is commonly used to reconstitute multi-dose peptide vials.
Bioavailability
The fraction of a dose that reaches the bloodstream in active form. Most peptides have poor oral bioavailability, so they are usually injected.
BPC-157
A synthetic peptide derived from a protein found in gastric juice, studied in animal models for tissue healing and recovery.
C
CJC-1295
A growth-hormone-releasing hormone (GHRH) analog that stimulates the pituitary to release growth hormone, often paired with a GHRP.
Concentration
How much peptide is dissolved per unit of liquid, usually expressed as mg/mL. It equals the vial amount divided by the water added.
D
Dead space
The small volume of liquid left in a syringe hub and needle after injecting. Low-dead-space insulin syringes waste less peptide.
G
GHK-Cu
A copper-binding tripeptide studied for skin, hair, and tissue repair, used both topically and by injection.
Ghrelin
A hunger hormone that also stimulates growth hormone release. Several secretagogue peptides mimic ghrelin at its receptor.
GHRH
Growth-hormone-releasing hormone. GHRH analogs such as sermorelin and CJC-1295 prompt the pituitary to make more growth hormone.
GHRP
Growth-hormone-releasing peptide. GHRPs such as ipamorelin and GHRP-6 trigger growth hormone release through the ghrelin receptor.
GIP
Glucose-dependent insulinotropic polypeptide, an incretin hormone. Tirzepatide activates both GIP and GLP-1 receptors.
GLP-1
Glucagon-like peptide-1, a gut hormone that boosts insulin, slows gastric emptying, and reduces appetite. The target of semaglutide and others.
H
Half-life
The time it takes for half of a dose to clear from the body. A longer half-life generally means less frequent dosing.
Hexarelin
A potent growth-hormone-releasing peptide in the GHRP family, studied for strong but short-lived GH release.
I
IGF-1
Insulin-like growth factor 1, a hormone produced largely in response to growth hormone that mediates many of its anabolic effects.
Insulin syringe (U-100)
A fine syringe marked in units where 100 units equals 1 mL. It is the standard tool for small subcutaneous peptide doses.
Intramuscular (IM)
An injection delivered into muscle tissue. Some peptides are given IM, though subcutaneous is more common for self-administration.
IU (International Unit)
A unit of measure based on biological activity rather than mass. Used for some hormones, though most peptides are dosed in mg or mcg.
L
Lyophilized
Freeze-dried into a stable powder. Peptides ship lyophilized and must be reconstituted with liquid before use.
M
mcg (microgram)
One thousandth of a milligram. Many peptide doses are measured in micrograms, so 250 mcg equals 0.25 mg.
Melanocortin
A receptor system involved in pigmentation and sexual function. PT-141 and melanotan act on melanocortin receptors.
MOTS-c
A mitochondrial-derived peptide studied for metabolism and exercise capacity.
P
Peptide
A short chain of amino acids, typically 2 to 50, that acts as a biological signal. Longer chains are classified as proteins.
Peptide bond
The chemical link that joins one amino acid to the next, forming the backbone of every peptide and protein.
R
Reconstitution
Dissolving a freeze-dried peptide with bacteriostatic water to create an injectable solution at a known concentration.
S
Secretagogue
A substance that prompts the body to secrete a hormone. Growth hormone secretagogues stimulate natural GH release rather than replacing it.
Sharps
Used needles and syringes. They must be disposed of in a rigid, puncture-resistant sharps container, never loose in the trash.
Somatostatin
A hormone that inhibits growth hormone release, acting as a natural brake on the systems many GH peptides try to stimulate.
Stacking
Running two or more peptides together, often to combine complementary effects such as a GHRH with a GHRP.
Subcutaneous (SubQ)
An injection into the fatty layer just under the skin. It is the most common route for self-administered peptides.
T
TB-500
A synthetic version of a fragment of thymosin beta-4, studied for recovery and tissue repair, often paired with BPC-157.
Titration
Gradually increasing a dose over weeks to reach a target while limiting side effects. Standard practice for GLP-1 medications.
V
Vial
The small sealed glass container that holds a peptide. A multi-dose vial provides several injections once reconstituted.