Peptide Glossary
A-Z reference of peptide and reconstitution terminology. 30 terms defined.
A
- Aliquot
- A measured portion drawn from a reconstituted vial. Drawing aliquots lets you divide a single vial into multiple doses without repeatedly piercing the stopper with a large-gauge needle.
- Amino Acid
- An organic molecule that serves as a building block of peptides and proteins. There are 20 standard amino acids. Peptides are short chains of amino acids, typically fewer than 50 residues.
- Ampoule
- A small sealed glass container holding a single dose of liquid. Unlike vials with rubber stoppers, ampoules are snapped open and cannot be resealed. Bacteriostatic water sometimes comes in ampoules.
B
- Bacteriostatic Water
- Sterile water containing 0.9% benzyl alcohol as a preservative. The benzyl alcohol inhibits bacterial growth, making it the preferred solvent for reconstituting peptides that will be used over multiple days.Reconstitution calculator
- Benzyl Alcohol
- The preservative used in bacteriostatic water at a concentration of 0.9%. It prevents microbial contamination in multi-use vials. Without it, reconstituted peptides must be used immediately or discarded.
- Bioavailability
- The fraction of an administered compound that reaches systemic circulation in active form. Subcutaneous injection typically provides higher bioavailability than oral administration for peptides, since peptides are degraded in the digestive tract.
C
- Cold Chain
- An unbroken series of refrigerated storage and transport steps that keeps a product within a specified temperature range (typically 2-8 C for peptides). Breaking the cold chain can denature the peptide and reduce potency.
- Cycle
- A defined period during which a compound is administered, followed by a period off. Cycle length varies by compound. Some peptides like BPC-157 are used in 4-6 week cycles, while GLP-1 agonists are used continuously.BPC-157 calculator
G
- Gauge
- A measurement of needle diameter. Higher gauge numbers mean thinner needles. Insulin syringes typically use 29-31 gauge needles, which are thin enough for subcutaneous peptide injection with minimal discomfort.
- GHRH (Growth Hormone Releasing Hormone)
- A hormone produced in the hypothalamus that stimulates the pituitary gland to release growth hormone. Synthetic GHRH analogs like CJC-1295 and sermorelin mimic this signaling to promote growth hormone secretion.CJC-1295/Ipamorelin calculator, Sermorelin calculator
- GLP-1 (Glucagon-Like Peptide-1)
- An incretin hormone that stimulates insulin release, suppresses glucagon, and slows gastric emptying. GLP-1 receptor agonists like semaglutide and tirzepatide are used for weight management and blood sugar control.Semaglutide calculator, Tirzepatide calculator
H
- Half-Life
- The time required for the concentration of a compound in the body to decrease by half. Half-life determines dosing frequency. Semaglutide has a half-life of about 7 days (dosed weekly), while BPC-157 has a plasma half-life under 30 minutes (dosed twice daily). Note: plasma half-life and duration of biological effect are distinct. BPC-157 clears the bloodstream quickly but its tissue-repair effects persist for 24-48 hours.Semaglutide calculator, BPC-157 calculator
I
- Insulin Syringe
- A syringe calibrated in units (U-100 scale: 100 units per 1ml). The standard tool for measuring and injecting reconstituted peptides. Available in 0.3ml (30 unit), 0.5ml (50 unit), and 1ml (100 unit) sizes.Reconstitution calculator
- Intramuscular (IM)
- An injection delivered into muscle tissue, typically the deltoid or gluteus. Some peptides can be administered intramuscularly, though subcutaneous injection is more common for most research peptides.
- IU (International Unit)
- A unit of measurement based on biological activity rather than mass. Used primarily for HGH and insulin. One IU of HGH equals approximately 333 mcg. Not interchangeable with syringe units on an insulin syringe.
L
- Loading Dose
- A higher initial dose given at the start of a protocol to reach effective levels faster. Some peptides use a loading phase (e.g., TB-500 at higher doses for the first 4-6 weeks) before transitioning to a maintenance dose.TB-500 calculator
- Lyophilized
- Freeze-dried. Most research peptides ship as a lyophilized powder (a dry cake or puck in the vial). Lyophilization removes water to improve stability during storage. The powder must be reconstituted before use.
- Lyophilization
- The freeze-drying process used to convert a liquid peptide solution into a stable dry powder. The solution is frozen, then placed under vacuum so the ice sublimates directly to vapor. This preserves the peptide structure for long-term storage.
M
- Maintenance Dose
- The ongoing dose used after an initial loading phase, typically lower than the loading dose. Designed to sustain the desired effect over a longer period.
- mcg (Microgram)
- One millionth of a gram (1/1000 of a milligram). Most peptide doses are measured in micrograms. For example, a typical BPC-157 dose is 250 mcg. Written as mcg or µg.BPC-157 calculator
P
- PCT (Post Cycle Therapy)
- A protocol used after discontinuing certain compounds to help restore natural hormone production. More commonly associated with anabolic steroids than peptides, though some growth hormone secretagogues may warrant a tapering protocol.
- Peptide
- A short chain of amino acids linked by peptide bonds, typically 2-50 amino acids in length. Longer chains are called proteins. Peptides act as signaling molecules in the body, influencing processes like growth, metabolism, and tissue repair.
R
- Reconstituted
- Describes a lyophilized peptide that has been dissolved in a solvent (usually bacteriostatic water) and is ready for use. Reconstituted peptides must be refrigerated at 2-8 C and used within their shelf life (typically 14-28 days).
- Reconstitution
- The process of adding a solvent (bacteriostatic or sterile water) to a lyophilized peptide powder to create an injectable solution. The water should be added slowly along the vial wall, not sprayed directly onto the powder. Never shake the vial.Reconstitution calculator
S
- Secretagogue
- A substance that promotes the secretion of another substance. Growth hormone secretagogues (like ipamorelin and GHRP-6) stimulate the pituitary gland to release growth hormone.CJC-1295/Ipamorelin calculator
- Stack
- The practice of using two or more compounds simultaneously. BPC-157 and TB-500 are commonly stacked for tissue repair research. Stacking should account for potential interactions between compounds.BPC-157 calculator, TB-500 calculator
- Sterile Water
- Water that has been sterilized and is free of microorganisms, but contains no preservative. Suitable for single-use reconstitution only. For multi-dose vials, bacteriostatic water is preferred because sterile water has no antimicrobial protection after opening.
- Subcutaneous (SubQ)
- An injection into the fatty tissue layer just beneath the skin. The most common injection route for research peptides. Typical injection sites include the abdomen (around the navel), upper thigh, and back of the upper arm.
T
- Titration
- Gradually adjusting a dose upward or downward to find the effective level while minimizing side effects. GLP-1 agonists like semaglutide use a titration schedule, starting at 0.25mg and increasing monthly.Semaglutide calculator
V
- Vial
- A small glass or plastic container sealed with a rubber stopper and aluminum crimp cap. Peptides are supplied in vials, typically containing 2mg, 5mg, or 10mg of lyophilized powder. The stopper allows multiple needle insertions for drawing doses.Reconstitution calculator