A comprehensive reference of terms commonly used in peptide research, dosage protocols, and reconstitution guides. Terms are organized alphabetically for easy navigation.
A
Amino Acid
An organic molecule that serves as a building block of peptides and proteins. There are 20 standard amino acids. Peptides are defined by their amino acid sequence — for example, BPC-157 is a chain of 15 amino acids, while HGH 191AA contains 191.
Anabolic
Refers to metabolic processes that build up complex molecules from simpler ones — for example, muscle protein synthesis. Several peptides studied in research contexts (such as growth hormone secretagogues) are investigated for their potential anabolic effects on lean tissue.
Anterior Pituitary
The front portion of the pituitary gland at the base of the brain. It produces and secretes several hormones, including growth hormone (GH), which is the target of many GH-related peptide research protocols.
B
Bacteriostatic Water (BAC Water)
Sterile water containing 0.9% benzyl alcohol as a preservative. Used as the standard diluent for reconstituting lyophilized peptides. The benzyl alcohol inhibits bacterial growth, allowing the reconstituted solution to be used over multiple days (typically up to 28–30 days when refrigerated).
Bioavailability
The proportion of a substance that enters systemic circulation and is available for biological activity after administration. Subcutaneous injection generally provides high bioavailability for peptides, while oral bioavailability for most peptides is very low due to digestive degradation.
Bioidentical
Structurally identical to a molecule produced naturally in the body. For example, somatropin (HGH 191AA) is described as bioidentical because its amino acid sequence matches the dominant form of human growth hormone produced by the pituitary gland.
Blend
A single vial containing two or more peptides pre-mixed together in lyophilized form. Blends are reconstituted and injected as one solution. Examples include CJC-1295/Ipamorelin blends and BPC-157/TB-500 blends. Compare with Stack.
BPC-157 (Body Protection Compound-157)
A synthetic pentadecapeptide (15 amino acids) derived from a protective protein found in gastric juice. It is one of the most widely researched peptides in the context of tissue repair, wound healing, and gastrointestinal protection.
C
Certificate of Analysis (COA)
A document provided by a manufacturer or third-party lab that reports the results of testing on a specific batch of product — typically including purity (via HPLC), identity, and sometimes endotoxin or sterility testing. A COA does not guarantee pharmaceutical-grade quality or regulatory compliance.
Concentration
The amount of peptide dissolved per unit volume of solution after reconstitution, usually expressed as mg/mL or mcg per unit. Concentration is determined by how much diluent (BAC water) you add to the vial. Example: 5 mg peptide + 2 mL BAC water = 2.5 mg/mL concentration.
Cycle
A defined period during which a peptide protocol is followed, typically measured in weeks. Many protocols specify an “on” period (active use) followed by an “off” period (break). Cycle length varies by peptide and research goal.
D
DAC (Drug Affinity Complex)
A chemical modification (specifically, a maleimidopropionic acid linker attached to lysine) that extends a peptide’s half-life by allowing it to bind to albumin in the bloodstream. CJC-1295 with DAC has a significantly longer half-life (days) compared to CJC-1295 without DAC (minutes).
Diluent
The liquid used to dissolve lyophilized peptide powder. The most common diluent for peptides is bacteriostatic water. Sterile water and sodium chloride solution are also used in some contexts, though they lack the preservative properties of BAC water.
Dose / Dosage
The specific amount of a peptide administered per injection, typically expressed in mg, mcg, or IU. Dosage protocols specify how much to inject, how often, and for how long. The correct dose depends on the peptide, the concentration after reconstitution, and the research protocol being followed.
G
GH (Growth Hormone)
A 191-amino acid peptide hormone produced by the anterior pituitary gland. It stimulates growth, cell reproduction, and cell regeneration. Recombinant forms (somatropin/HGH 191AA) are used in clinical medicine for defined deficiency states.
GHRH (Growth Hormone Releasing Hormone)
A hypothalamic peptide that stimulates the pituitary to release growth hormone. Synthetic analogues include CJC-1295 (with and without DAC), Sermorelin, and Tesamorelin. These work by amplifying the body’s own GH release pulses rather than providing exogenous GH directly.
GHRP (Growth Hormone Releasing Peptide)
A class of synthetic peptides that stimulate GH release through the ghrelin receptor (GHS-R). Examples include GHRP-2, GHRP-6, Ipamorelin, and Hexarelin. They work through a different pathway than GHRH analogues and are sometimes combined with them for synergistic effects.
GLP-1 (Glucagon-Like Peptide-1)
An incretin hormone involved in glucose metabolism, appetite regulation, and insulin secretion. GLP-1 receptor agonists (such as semaglutide, tirzepatide, and retatrutide) are among the most widely discussed peptides in metabolic research.
H
Half-Life
The time it takes for half of a substance to be eliminated from the body or lose its biological activity. Half-life determines dosing frequency — short half-life peptides (e.g., CJC-1295 no DAC at ~30 minutes) require more frequent dosing, while long half-life peptides (e.g., semaglutide at ~7 days) can be dosed weekly.
HGH 191AA
Recombinant human growth hormone containing the full 191-amino acid sequence identical to the dominant form of natural pituitary GH. Also called somatropin. The “191AA” label distinguishes it from the older 192-amino acid somatrem variant. See also Somatropin.
HPLC (High-Performance Liquid Chromatography)
An analytical chemistry technique used to determine peptide purity. Purity is expressed as a percentage — for example, “98% purity by HPLC” means 98% of the sample is the target peptide. HPLC results typically appear on Certificates of Analysis.
I
IGF-1 (Insulin-like Growth Factor 1)
A hormone primarily produced by the liver in response to growth hormone stimulation. IGF-1 mediates many of GH’s anabolic effects on tissues. IGF-1 blood levels are commonly monitored during GH-related protocols as a marker of GH activity.
IM (Intramuscular)
An injection route where the substance is delivered directly into muscle tissue. Less common for peptides than subcutaneous injection, but used for some compounds like HCG and certain GH protocols.
International Unit (IU)
A unit of measurement for biological activity, not weight. Used for specific peptides where potency has been standardized — primarily HGH (≈3 IU per 1 mg) and HCG (where IU reflects bioassay-determined potency). Not interchangeable with syringe “units,” which are volume marks.
IV (Intravenous)
An injection route where the substance is delivered directly into a vein. Rarely used for peptide research protocols — most peptides are administered subcutaneously (SubQ) or intramuscularly (IM).
L
Loading Dose
An initial higher dose given at the start of a protocol to rapidly reach therapeutic concentration levels, followed by lower maintenance doses. Some peptide protocols (particularly GLP-1 agonists like semaglutide) use a titration approach that starts low and ramps up, which is the opposite of a loading dose.
Lyophilization (Freeze-Drying)
The process of removing water from a substance by freezing it and then reducing pressure to allow the frozen water to sublimate (transition directly from ice to vapor). Peptides are lyophilized for stability — the resulting powder can be stored much longer than a liquid solution and is reconstituted with BAC water before use.
M–O
mcg (Microgram)
A unit of weight equal to one-millionth of a gram, or one-thousandth of a milligram (1 mg = 1,000 mcg). Many peptides are dosed in micrograms — for example, typical Ipamorelin research doses are 100–300 mcg per injection. Sometimes written as µg.
mg (Milligram)
A unit of weight equal to one-thousandth of a gram. Used to describe both the total peptide content in a vial (e.g., “5 mg vial”) and per-injection doses for peptides dosed at milligram scale (e.g., “0.25 mg semaglutide”).
mL (Milliliter)
A unit of volume equal to one-thousandth of a liter. Used to measure the amount of BAC water added during reconstitution and the volume of solution drawn into a syringe. On a U-100 insulin syringe, 1 mL = 100 units.
P–R
Peptide
A short chain of amino acids linked by peptide bonds. Generally defined as containing 2–50 amino acids (chains longer than ~50 amino acids are typically called proteins). Peptides serve as signaling molecules, hormones, and structural components in biological systems.
Potency
The measure of a substance’s biological activity per unit of weight. For peptides, potency is influenced by purity, proper handling and storage, and correct reconstitution. Degraded or improperly stored peptides may lose potency even if the weight of powder remains the same.
Reconstitution
The process of dissolving lyophilized (freeze-dried) peptide powder in a liquid diluent (typically bacteriostatic water) to create an injectable solution. Proper reconstitution involves gently adding the diluent along the vial wall and allowing the powder to dissolve without shaking or agitating.
S
Secretagogue
A substance that stimulates the secretion of another substance. In the peptide context, “GH secretagogues” are compounds that stimulate the body’s natural release of growth hormone — as opposed to exogenous GH (like HGH 191AA), which replaces the hormone directly. Examples include CJC-1295, Ipamorelin, GHRP-2, GHRP-6, and MK-677.
Somatropin
The generic pharmaceutical name for recombinant human growth hormone with the native 191-amino acid sequence. Brand-name somatropin products include Humatrope, Genotropin, Norditropin, and others. Also referred to as HGH 191AA in research contexts.
Stack
A protocol involving two or more separate peptide vials used together in a coordinated dosing schedule. Unlike a blend (which combines peptides in one vial), a stack requires separate reconstitution and injection of each peptide. Example: running BPC-157 and TB-500 from separate vials on the same schedule.
Sterile Water
Water that has been sterilized and is free of microorganisms, but does not contain a preservative like benzyl alcohol. If sterile water is used instead of bacteriostatic water for reconstitution, the solution should be used within 24–48 hours as there is no preservative to inhibit bacterial growth.
SubQ / SC (Subcutaneous)
An injection route where the substance is delivered into the fatty tissue layer just beneath the skin. This is the most common injection method for peptide research protocols. Common injection sites include the lower abdomen, thigh, and upper arm.
T–U
TB-500 (Thymosin Beta-4 Fragment)
A synthetic peptide based on a naturally occurring 43-amino acid protein (Thymosin Beta-4) involved in cell migration, tissue repair, and inflammation modulation. TB-500 is commonly researched alongside BPC-157 in tissue-recovery protocols.
Titration
The practice of gradually adjusting a dose — usually starting low and increasing incrementally — to find the optimal effective dose while minimizing side effects. GLP-1 agonist protocols (e.g., semaglutide, tirzepatide) typically follow strict titration schedules over several weeks.
U–V
U-100 Syringe
An insulin syringe calibrated so that 100 “units” equals 1 mL of liquid. Each unit mark represents 0.01 mL. This is the most common syringe type used in peptide protocols. Also available in U-50 (50 units = 0.5 mL) and U-20 (20 units = 0.2 mL) for more precise small-volume measurements.
Units (Syringe Units vs. International Units)
A critical distinction: Syringe units are volume marks on an insulin syringe (U-100: 100 units = 1 mL, so 1 unit = 0.01 mL). International Units (IU) measure biological potency of specific peptides like HGH and HCG. These are completely different measurements. Always clarify which “units” a protocol refers to.
Vial
A small sealed glass or plastic container holding lyophilized peptide powder. Most peptide vials are sealed with a rubber stopper and aluminum crimp cap. The vial label indicates the peptide name and total content (e.g., “BPC-157 5mg”). After reconstitution, the solution is drawn from the vial through the rubber stopper using a syringe.
W
WADA (World Anti-Doping Agency)
The international organization that maintains the Prohibited List of substances banned in competitive sports. Many peptides are on this list, including growth hormone, GH fragments, GH secretagogues (CJC-1295, Ipamorelin, GHRP-2, GHRP-6, MK-677), and GLP-1 agonists in certain competition contexts.