Research use only. Not for human consumption. 18+ only.

Peptide glossary

Plain definitions for the terms, compounds and acronyms you will meet in peptide research and on this platform.

For research and educational purposes only. Not medical advice.

Acetylation
A chemical modification in which an acetyl group is added to a molecule, often used to enhance the stability or bioavailability of peptide compounds.
Adverse Event
Any unwanted medical occurrence during or after use of a compound, whether or not the compound caused it. Clinical trials record adverse events to build up a side effect profile.
Agonist
A molecule that binds to a receptor and activates it, producing a response. GLP-1 receptor agonists such as semaglutide activate the GLP-1 receptor in the same way the natural hormone does.Metabolic and weight loss peptides
Amidation
Replacing the carboxyl group at the end of a peptide chain with an amide group. A common modification, as in N-Acetyl Semax Amidate, that can slow breakdown by enzymes.
Amino Acid
The building blocks of peptides and proteins. Peptides are chains of amino acids linked by peptide bonds. There are 20 standard amino acids used in biological processes.
Anabolic
Describes processes that build larger molecules and tissues from smaller ones, such as muscle protein synthesis. The opposite of catabolic.Muscle growth and performance peptides
Analogue
A synthetic compound modelled on a natural molecule, with a changed structure that alters its potency, stability or half-life. CJC-1295, for example, is an analogue of GHRH.
Angiogenesis
The formation of new blood vessels from existing ones. Angiogenesis is an important part of wound healing and is one of the processes studied with healing peptides such as BPC-157 and TB-500.Healing and recovery peptides
Antagonist
A molecule that binds to a receptor without activating it, blocking the natural signal from getting through.
Anxiolytic
Reducing anxiety. Selank is one of the peptides studied for anxiolytic effects.Peptides for anxiety and mood
Auto Pen
A reusable injector pen that holds a cartridge of reconstituted peptide and delivers a set volume with each click of the dial. Doses are counted in clicks rather than read off a syringe.Peptide calculator
BAC Water
Bacteriostatic Water - sterile water containing 0.9% benzyl alcohol as a preservative. Used to reconstitute lyophilised peptides and inhibits microbial growth, allowing multi-dose use.How to reconstitute
BDNF
Brain-Derived Neurotrophic Factor - a protein that supports the survival of neurons and the formation of new connections between them. Several nootropic peptides, including Semax, are studied for their effect on BDNF.Cognitive enhancement peptides
Bioavailability
The proportion of a dose that reaches the bloodstream in active form. Injected peptides have high bioavailability, while most peptides taken by mouth are broken down in the gut before they can be absorbed.
Bioregulator
A very short peptide, usually two to four amino acids long, proposed to regulate gene activity in a specific organ or tissue. The term comes from the research of Professor Vladimir Khavinson.Khavinson bioregulators
Blend
Two or more research peptides physically combined into a single vial at fixed dosages, reconstituted and injected as one shot. Differs from a stack: a blend is a single mixed preparation, while a stack uses separate vials injected individually according to a protocol.Peptide blends
BPC-157
Body Protection Compound-157 - a synthetic peptide derived from a protective stomach protein (BPC). Studied in research for its effects on tissue repair, angiogenesis, and inflammation modulation.Research profile
Cartridge
The glass reservoir inside an injector pen that holds the reconstituted solution, most often 3 mL. The pen pushes a fixed volume out of it with each click.Peptide calculator
Catabolic
Describes processes that break molecules and tissues down to release energy. The opposite of anabolic.
CJC-1295
A synthetic analogue of Growth Hormone Releasing Hormone (GHRH). Research compounds may be DAC (Drug Affinity Complex) modified for extended half-life, or without DAC for shorter activity.Research profile
Click
One step of the dial on an injector pen. On most 3 mL pens one click moves 0.01 mL, the same as one unit on a U-100 syringe, though some pens use bigger or smaller steps.Peptide calculator
Clinical Trial Phases
The stages a compound goes through in human testing. Phase 1 checks safety in a small group, phase 2 looks at effectiveness and dosing, and phase 3 confirms the results in a large group before a licence is applied for.
COA (Certificate of Analysis)
A lab document reporting the identity, purity and content of a batch, usually from HPLC and mass spectrometry testing. A useful COA comes from an independent lab and matches the batch number on the vial.How to source responsibly
Collagen
The main structural protein in skin, tendons, ligaments and bone. Copper peptides such as GHK-Cu are studied for their effect on collagen production.Skin and anti-aging peptides
Compounding
The preparation of a medicine by a licensed pharmacy for an individual patient, rather than mass manufacture. Some peptides are available through compounding pharmacies in certain countries.
Concentration
The amount of active peptide per unit volume of reconstituted solution, typically expressed in mg/mL or mcg/mL. Determined by the amount of powder reconstituted in a given volume of BAC water.Peptide calculator
Contraindication
A condition or circumstance that makes a treatment inadvisable, such as pregnancy or a particular medical history. Each research profile lists the warnings reported for that compound.
Cycle
A planned period of use followed by a break. Many peptide protocols are run in cycles, partly to reduce the chance of the body becoming less responsive over time.
DAC (Drug Affinity Complex)
A chemical attachment that lets a peptide bind to albumin in the blood, extending its half-life from minutes to days. CJC-1295 with DAC is the best-known example.
Dead Space
The small volume of liquid left in a syringe hub and needle after the plunger is fully pressed. Low dead space syringes waste less solution with each injection.
Dosage
The amount of a compound administered in a single dose, typically measured in micrograms (mcg) or milligrams (mg) for peptide research.Peptide calculator
DSIP
Delta Sleep-Inducing Peptide - a neuropeptide studied for its potential effects on sleep architecture and stress response in research settings.Research profile
Endogenous
Produced naturally inside the body. Growth hormone made by your own pituitary gland is endogenous; growth hormone given by injection is exogenous.
Epithalon
A tetrapeptide (Ala-Glu-Asp-Gly) derived from the epithalamus. Studied in longevity and anti-ageing research for its potential influence on telomere length and melatonin regulation.Research profile
Evidence Grade
The Peptide Volt rating for how strong the research behind a peptide is. A means human randomised controlled trials, B means smaller or observational human studies, C means mostly animal or lab studies, and D means theoretical or very early evidence.Research library
Exogenous
Coming from outside the body, such as a compound taken by injection or by mouth. The opposite of endogenous.
FDA
Food and Drug Administration - the agency that approves medicines in the United States. Approval covers a specific use, dose and patient group, not every way a compound might be used.
Follistatin
A protein that inhibits myostatin and activin signalling. Research in this area focuses on its potential to influence muscle growth and tissue regeneration.Research profile
GH (Growth Hormone)
Human Growth Hormone - a peptide hormone produced by the pituitary gland that stimulates growth, cell reproduction, and regeneration. Many peptide research compounds aim to stimulate endogenous GH secretion.Growth hormone secretagogues
Ghrelin
A hunger hormone made mainly in the stomach. It also triggers growth hormone release through the ghrelin receptor (GHS-R1a), which is the receptor GHRPs and ipamorelin act on.Growth hormone secretagogues
GHRH
Growth Hormone Releasing Hormone - a peptide produced in the hypothalamus that stimulates the pituitary to secrete growth hormone. Synthetic analogues like CJC-1295 mimic its action.Growth hormone secretagogues
GHRP
Growth Hormone Releasing Peptide - a class of peptides (e.g. GHRP-2, GHRP-6, Ipamorelin) that stimulate GH release by acting on ghrelin receptors. Often stacked with GHRH analogues.Growth hormone secretagogues
GIP
Glucose-dependent Insulinotropic Polypeptide - a gut hormone that increases insulin release after meals. Tirzepatide activates both the GIP and GLP-1 receptors.Metabolic and weight loss peptides
GLP-1
Glucagon-Like Peptide-1 - a gut hormone released after eating that increases insulin release, slows stomach emptying and reduces appetite. GLP-1 receptor agonists such as semaglutide are licensed for type 2 diabetes and weight management.Peptides for fat loss
Glucagon
A hormone made by the pancreas that raises blood sugar and increases energy use. Retatrutide is studied as a triple agonist of the GLP-1, GIP and glucagon receptors.Metabolic and weight loss peptides
GnRH
Gonadotropin-Releasing Hormone - a hormone from the hypothalamus that signals the pituitary to release LH and FSH. Gonadorelin is a synthetic form of GnRH, and kisspeptin acts one step further upstream.Sexual health peptides
Half-Life
The time it takes for the concentration of a compound in the body to reduce by half. Peptides typically have short half-lives (minutes to hours) due to enzymatic degradation.
HPLC
High-Performance Liquid Chromatography - the standard lab test for peptide purity. It separates a sample into its components and reports the intended peptide as a percentage of the total.How to source responsibly
IGF-1
Insulin-Like Growth Factor 1 - a hormone primarily produced by the liver in response to growth hormone stimulation. Mediates many of GH's anabolic effects in research.Research profile
Immunomodulator
A substance that adjusts immune activity, either strengthening or calming it. Thymosin Alpha-1 is one of the most studied immunomodulating peptides.Immune and inflammatory peptides
In Vitro
Research carried out outside a living organism, for example on cells in a dish. In vitro results often do not carry over to people.
In Vivo
Research carried out in a living organism, either an animal or a human.
Injection Site Reaction
Redness, swelling, itching or a small lump where an injection went in. Usually mild and short-lived. Rotating injection sites helps to reduce them.How to inject
Insulin Sensitivity
How strongly the body's cells respond to insulin. Low insulin sensitivity (insulin resistance) makes it harder to control blood sugar and is a focus of metabolic peptide research.Metabolic and weight loss peptides
Insulin Syringe
A small syringe marked in units rather than mL, used to measure peptide doses. On a U-100 insulin syringe, 100 units equal 1 mL.Peptide calculator
Intramuscular (IM)
An injection into a muscle, usually with a longer needle than a subcutaneous injection. A small number of peptides are given this way.How to inject
Intranasal
Given as a nasal spray and absorbed through the lining of the nose. Semax and Selank are commonly used this way.
Ipamorelin
A selective GHRP that stimulates GH release with minimal effect on cortisol and prolactin. Commonly studied alongside CJC-1295 as a GHRH/GHRP combination.Research profile
IU (International Units)
A unit of measurement for biological activity of substances. Some peptides (e.g. HGH) are measured in IUs. The conversion to weight varies by substance.Peptide calculator
LH and FSH
Luteinising Hormone and Follicle-Stimulating Hormone - pituitary hormones that drive testosterone and oestrogen production and fertility. Kisspeptin, gonadorelin and hCG research centres on this hormone axis.Sexual health peptides
Lipolysis
The breakdown of stored fat into fatty acids and glycerol that the body can burn for energy. AOD-9604 is one of the peptides studied for its effect on lipolysis.Peptides for fat loss
Loading Dose
A higher starting dose used to reach the target level faster, followed by a lower maintenance dose.
Lyophilisation
Freeze-drying: the process used to remove water from peptide compounds to produce a stable powder (lyophilate) that can be stored and later reconstituted. The standard form in which peptides are supplied.How to reconstitute
Maintenance Dose
The regular dose used once a protocol has reached its target level, often lower than any loading dose.
Mass Spectrometry (MS)
A lab test that measures the mass of molecules, used to confirm that a sample really is the peptide on the label. Often reported alongside HPLC on a certificate of analysis.How to source responsibly
MCG / Microgram
One millionth of a gram (0.001 mg). Many peptide research doses are measured in micrograms due to the high potency of these compounds.Peptide calculator
Mechanism of Action
How a compound produces its effect in the body, for example which receptor it binds to and what that sets off. Each research profile has a mechanism section.Research library
Melanocortin Receptors
A family of five receptors (MC1R to MC5R) involved in skin pigmentation, appetite, inflammation and sexual function. Melanotan II and PT-141 both act on them.Tanning and pigmentation peptides
MG / Milligram
One thousandth of a gram, equal to 1,000 mcg. Vial contents are usually given in mg, while many doses are given in mcg.Peptide calculator
MHRA
Medicines and Healthcare products Regulatory Agency - the UK regulator for medicines and medical devices.
MK-677 (Ibutamoren)
A non-peptide ghrelin receptor agonist that stimulates GH and IGF-1 secretion. Orally active and long-acting. Used in research studying GH axis effects.
ML / Millilitre
A unit of volume equal to one thousandth of a litre. On a U-100 insulin syringe, 1 mL is 100 units, so 0.1 mL is 10 units.Peptide calculator
Neuroprotection
Protecting nerve cells from damage or death, for example after injury or in age-related decline. Several cognitive peptides are studied for neuroprotective effects.Cognitive enhancement peptides
Nootropic
A substance studied for its effect on memory, focus, learning or other aspects of thinking.Peptides for cognitive performance
Off-Label Use
Using a licensed medicine for a purpose, dose or patient group that its licence does not cover.
Palmitoylation
Attaching palmitic acid, a fatty acid, to a peptide so it passes through the skin more easily. Used in cosmetic peptides such as Pal-GHK and palmitoyl tetrapeptide-7.Cosmetic and topical peptides
PEGylation
Attaching chains of polyethylene glycol (PEG) to a peptide to slow its breakdown and clearance, extending its half-life. PEG-MGF is a PEGylated form of MGF.
Peptide
A short chain of amino acid residues linked by peptide bonds. Peptides are smaller than proteins (typically fewer than 50 amino acids) and can have wide-ranging biological activities.What peptides are
Peptide Bond
The chemical bond that links one amino acid to the next in a peptide chain, formed between the amino group of one and the carboxyl group of the other.
Pharmacodynamics (PD)
What a compound does to the body: the effects it has and how they change with dose.
Pharmacokinetics (PK)
What the body does to a compound: how it is absorbed, distributed, broken down and cleared. Half-life is a pharmacokinetic measure.
Pituitary Gland
A small gland at the base of the brain that releases growth hormone, LH, FSH and several other hormones. Many peptides work by signalling to it.Growth hormone secretagogues
Placebo
An inactive treatment given to a comparison group in a trial, so the real effect of a compound can be told apart from expectation and chance.
Pre-Clinical
Research done before human trials, in cells and animals. Most research peptides have mainly pre-clinical evidence, which is why many carry a C or D evidence grade.
Prescription-Only Medicine (POM)
A UK category for medicines that can only be supplied against a prescription. Licensed GLP-1 medicines such as semaglutide are prescription-only.
Priming
Pushing a small amount of solution through a new pen needle before the first dose to clear air, so the dose that follows is accurate.Peptide calculator
Protocol
A structured research plan defining dosage, timing, frequency, duration, and administration route for a peptide compound or combination.
PT-141 (Bremelanotide)
A synthetic melanocortin peptide studied for its effects on sexual function and libido via central nervous system pathways rather than vascular mechanisms.Research profile
Pulsatile Release
Release in bursts rather than a steady stream. The body releases growth hormone in pulses, mostly during deep sleep, and GH secretagogues are studied for strengthening those pulses.Growth hormone secretagogues
Purity
The share of a sample that is the intended peptide, usually measured by HPLC and stated as a percentage on the certificate of analysis.How to source responsibly
RCT (Randomised Controlled Trial)
A study that randomly splits participants into a group that gets the compound and a comparison group, often on placebo. The strongest kind of evidence, and the basis of an A evidence grade.
Receptor
A protein on or inside a cell that a specific molecule binds to, triggering a response. Most peptides work by binding to a receptor.
Reconstitution
The process of dissolving a lyophilised (freeze-dried) peptide powder in a sterile solution (typically BAC water or sterile water) to create an injectable solution.How to reconstitute
Research Chemical
A compound used for scientific research and laboratory study. Not approved for human consumption or therapeutic use. Sold legally for research purposes only.
Satellite Cells
Muscle stem cells that repair and grow muscle fibres after damage. MGF and IGF-1 are studied for their role in activating them.Muscle growth and performance peptides
Secretagogue
A substance that makes a gland release (secrete) another substance. Growth hormone secretagogues make the pituitary release more of its own growth hormone.Growth hormone secretagogues
Selank
A synthetic heptapeptide analogue of tuftsin. Studied in nootropic and anxiolytic research for its potential effects on cognitive performance and stress response.Research profile
Semax
A synthetic peptide derived from ACTH (adrenocorticotropic hormone). Studied for its potential neuroprotective and nootropic effects in research settings.Research profile
Senescence
The state in which a cell stops dividing but does not die. Senescent cells build up with age, and senolytic compounds such as FOXO4-DRI are studied for clearing them.Peptides for longevity
Stack
A structured research protocol combining two or more peptides used together but kept in separate vials, each injected individually. Stacks are chosen for synergistic effects across multiple pathways. Differs from a blend: a stack uses separate preparations rather than a single mixed vial.Stack of the week
Sterile Water
Water for injection with no preservative. It can be used to reconstitute peptides, but unlike BAC water it does not stop bacterial growth once the vial has been opened, so it suits single use.How to reconstitute
Storage
Most lyophilised peptides keep longest cold and away from light. Once reconstituted, a vial is kept in the fridge at 2 to 8°C and used within the time given on its research profile.Research library
Subcutaneous (SubQ)
An injection into the fatty layer just under the skin, usually around the stomach or thigh. The most common route for peptide injections.How to inject
Tachyphylaxis
A drop in response to a compound after repeated doses, often because its receptors become less sensitive. Also called desensitisation. One reason some protocols build in breaks.
TB-500 (Thymosin Beta-4)
A synthetic version of a naturally occurring peptide that regulates actin, a key protein in cell structure. Studied for its potential role in tissue repair, wound healing, and inflammation.Research profile
Telomere
A protective cap of repeated DNA at the end of each chromosome that shortens every time a cell divides. Telomere length is used as a marker of cellular ageing, and Epithalon is studied for its effect on telomerase, the enzyme that rebuilds it.Peptides for longevity
Thymus
A gland behind the breastbone where T cells mature. It shrinks with age, and thymic peptides such as Thymosin Alpha-1 and Thymalin are studied for supporting immune function.Immune and inflammatory peptides
Titration
Raising (or lowering) a dose gradually over time. GLP-1 protocols, for example, usually start low and step up every few weeks to limit nausea.Metabolic and weight loss peptides
Topical
Applied to the skin rather than injected or swallowed. Cosmetic peptides such as Argireline and Matrixyl are used topically in creams and serums.Cosmetic and topical peptides
Units (Syringe)
The markings on an insulin syringe. On a U-100 syringe, 1 unit is 0.01 mL. Syringe units measure volume, not the amount of peptide, and are not the same thing as IU.Peptide calculator
Vial
A small glass container holding the lyophilised peptide powder. Typically sealed with a rubber stopper that can be pierced with a syringe for reconstitution or withdrawal.What you will need
Washout Period
A break with no doses between cycles, or before starting a different compound, so the previous one has cleared and its effects do not overlap.

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