Peptide Glossary

Traditional compounding pharmacies that prepare medications for individual patients with valid prescriptions, regulated primarily by states.

Outsourcing facilities registered with FDA that can compound larger quantities without individual prescriptions, subject to GMP requirements.

Any undesirable experience associated with use of a peptide or drug, whether or not considered related to the treatment.

Organic molecules that serve as the building blocks of proteins and peptides. There are 20 standard amino acids used in protein synthesis.

The formation of new blood vessels from existing vasculature, a process important in healing and tissue repair.

Research conducted in animals to understand biological effects before human testing. Most peptide research is at this stage.

Peptides that have bactericidal or bacteriostatic activity, forming part of the innate immune system. LL-37 is a human antimicrobial peptide.

Sterile water containing 0.9% benzyl alcohol as a preservative, used for reconstituting peptides for multiple-use applications.

Brain-Derived Neurotrophic Factor, a protein that supports neuron survival and growth. Semax increases BDNF levels.

The strength of interaction between a peptide and its receptor. Higher affinity generally means more potent effect at lower doses.

The proportion of a drug or substance that enters circulation and is able to have an active effect when introduced into the body.

The end of a peptide chain, containing a free carboxyl group (-COOH). The C-terminus is the conventional ending point when writing peptide sequences.

A document from a testing laboratory that confirms the identity, purity, and quality specifications of a substance.

A research study conducted in human subjects to evaluate the safety and efficacy of a medical intervention, conducted in phases I through IV.

A pharmacy that prepares customized medications by mixing, combining, or altering ingredients based on prescriptions.

A condition or factor that serves as a reason to withhold a certain treatment due to potential harm.

A peptide in which the amino acid sequence forms a ring structure, often increasing stability and receptor binding specificity compared to linear peptides.

The formation of a ring structure in a peptide, often used to increase stability and receptor specificity.

Protection of cells from harmful agents or stress, a property attributed to certain peptides like BPC-157.

The mirror image (enantiomer) of naturally occurring L-amino acids. Incorporating D-amino acids into peptides can increase protease resistance.

Reduced responsiveness to a drug after repeated exposure, requiring higher doses to achieve the same effect.

A peptide composed of exactly two amino acids joined by a single peptide bond. Examples include carnosine and anserine.

A graph showing the relationship between the dose of a substance and the magnitude of its effect, used to determine optimal dosing.

A clinical trial design where neither participants nor researchers know who receives the treatment versus placebo, reducing bias.

A reaction between a peptide and another substance (drug, supplement, food) that alters the effect of one or both.

The concentration of a substance that produces 50% of its maximum effect. Used to measure potency of agonists.

A peptide naturally produced within the body, as opposed to exogenous peptides administered externally. GHK-Cu is an endogenous copper peptide.

Toxic components from gram-negative bacteria that can cause fever and inflammation if present in injectable products.

Official authorization from the U.S. Food and Drug Administration to market a drug for specific uses after demonstrated safety and efficacy.

Growth Hormone Releasing Hormone, a hypothalamic peptide that stimulates the pituitary to release growth hormone.

Growth Hormone Releasing Peptides, synthetic peptides that stimulate growth hormone release through the ghrelin receptor.

Glucose-dependent insulinotropic polypeptide, a hormone that stimulates insulin release. Combined with GLP-1 in dual-agonist drugs like tirzepatide.

Glucagon-like peptide-1, a hormone produced in the gut that stimulates insulin secretion and reduces appetite. The target of medications like semaglutide.

Good Manufacturing Practice, a system of quality assurance ensuring products are consistently produced according to quality standards.

FDA designation for substances considered safe based on long history of use or scientific consensus, not requiring formal approval.

A peptide hormone produced by the pituitary gland that stimulates growth, cell reproduction, and regeneration.

The time required for the concentration of a substance in the body to be reduced by half through metabolism or excretion.

High-Performance Liquid Chromatography, an analytical technique used to separate, identify, and quantify components in a mixture.

The concentration of a substance required to inhibit a biological process by 50%. Used to compare potency of different compounds.

Insulin-like Growth Factor 1, a hormone similar in structure to insulin that mediates many effects of growth hormone.

The ability of a peptide to trigger an immune response, potentially forming antibodies that reduce effectiveness.

Experiments performed outside a living organism, typically in test tubes or cell cultures. Latin for "in glass."

Experiments performed within a living organism, such as animal studies. Latin for "in the living."

The practice of varying injection locations to prevent lipodystrophy, scarring, and ensure consistent absorption.

Administration directly into muscle tissue, allowing for faster absorption than subcutaneous injection.

Delivery of peptides through the nasal mucosa, commonly used for Semax and Selank. Provides rapid absorption and brain access.

Administration directly into a vein, providing 100% bioavailability and immediate effect. Used for NAD+ infusions.

A drug being studied in clinical trials but not yet approved for marketing. Retatrutide and Orforglipron are current examples.

The dose of a substance that kills 50% of test animals. A measure of acute toxicity; higher LD50 means lower toxicity.

The attachment of fatty acid chains to peptides, used to extend half-life by promoting albumin binding.

Abnormal fat distribution, including accumulation or loss, that can occur at repeated injection sites.

A higher initial dose given to rapidly achieve therapeutic levels in the body before switching to a lower maintenance dose.

A freeze-drying process used to preserve peptides by removing water content, resulting in a stable powder form.

The regular ongoing dose taken to maintain therapeutic levels after initial loading, typically lower than the loading dose.

An analytical technique that measures the mass-to-charge ratio of ions, used to identify and confirm peptide molecular weight.

The specific biochemical interaction through which a drug or peptide produces its pharmacological effect on the body.

A family of peptide hormones including MSH that regulate pigmentation, inflammation, and energy homeostasis.

The start of a peptide chain, containing a free amino group (-NH2). Convention dictates peptide sequences are written starting from the N-terminus.

Peptides released by neurons that act as neurotransmitters or neuromodulators, influencing brain function. Examples include endorphins and substance P.

Mechanisms and strategies used to protect neurons from injury, degeneration, or death.

Using an FDA-approved drug for a purpose other than its approved indication. Tesamorelin for fat loss is an example.

A short chain of amino acids, typically containing 2-20 amino acid residues linked by peptide bonds.

A peptide designed to be taken by mouth. Challenging due to stomach acid degradation; BPC-157 (stable form) and MK-677 are examples.

A drug developed for rare diseases affecting fewer than 200,000 Americans, eligible for special FDA incentives.

The attachment of polyethylene glycol chains to a molecule, typically to increase half-life and reduce immunogenicity.

A modified version of a natural peptide designed to improve stability, potency, or selectivity while maintaining biological activity.

A covalent chemical bond formed between two amino acids when the carboxyl group of one reacts with the amino group of another, releasing water.

The practice of using peptides for a defined period followed by a break to prevent desensitization and allow receptor recovery.

A portion of a larger peptide or protein that retains specific biological activity. AOD-9604 is a fragment of human growth hormone.

A collection of peptides with systematically varied sequences used in drug discovery to identify peptides with desired biological activities.

A small molecule designed to mimic the biological activity of a peptide while having improved drug-like properties such as oral bioavailability.

The specific order of amino acids in a peptide chain, written from N-terminus to C-terminus using single or three-letter amino acid codes.

A chemical modification that constrains peptide structure using hydrocarbon bridges, improving stability and cell permeability of helical peptides.

The study of what a drug does to the body - its biochemical and physiological effects and mechanism of action.

The study of how the body absorbs, distributes, metabolizes, and eliminates a drug. Determines how often and how much to dose.

Large-scale clinical trials involving hundreds to thousands of patients to confirm efficacy, monitor side effects, and compare to existing treatments.

A study design comparing the test treatment to an inactive substance (placebo) to determine the true effect of the treatment.

A longer chain of amino acids, typically more than 20 residues, but not large enough to be considered a protein.

Research conducted before human trials, typically involving laboratory experiments and animal studies to assess safety and potential efficacy.

Large, complex molecules made up of long chains of amino acids. Proteins are essential for the structure, function, and regulation of the body's tissues and organs.

A substance that binds to and activates a receptor, triggering a biological response similar to the naturally occurring ligand.

A substance that binds to a receptor but does not activate it, blocking the action of agonists.

Decrease in receptor number or sensitivity after prolonged agonist exposure, reducing peptide effectiveness over time.

A peptide produced using recombinant DNA technology, where the peptide gene is inserted into host cells (bacteria, yeast) that then produce the peptide.

The process of mixing a lyophilized (freeze-dried) peptide powder with bacteriostatic water or saline to create an injectable solution.

Substances sold for laboratory research purposes, not approved for human consumption but often used off-label.

Any substance that promotes secretion of another substance, commonly used to describe compounds that stimulate hormone release.

A cell that has stopped dividing but remains metabolically active, secreting inflammatory factors. FOXO4-DRI targets these cells.

An effect of a peptide other than the intended therapeutic effect. Can be beneficial, neutral, or harmful.

A short peptide sequence that directs newly synthesized proteins to their correct cellular location, typically cleaved off after delivery.

A method of peptide synthesis where amino acids are sequentially added to a growing chain attached to a solid support.

Combining multiple peptides simultaneously to achieve synergistic effects. The Wolverine Stack (BPC-157 + TB-500) is a popular example.

Administration of a substance into the fatty tissue layer between the skin and muscle, commonly used for peptide delivery.

A peptide manufactured through chemical synthesis rather than extracted from biological sources, allowing precise control over sequence and modifications.

Rapid decrease in response to a drug after repeated administration, requiring higher doses for same effect.

Two or more peptide sequences linked together to combine multiple biological activities or improve pharmacokinetic properties.

An enzyme that maintains telomere length in chromosomes, potentially extending cellular lifespan. Epitalon activates telomerase.

Protective caps at the ends of chromosomes that shorten with each cell division. Telomere length is associated with biological aging.

The range of doses between the minimum effective dose and the dose that causes unacceptable side effects.

The process of gradually adjusting dosage to find the optimal amount that provides benefits while minimizing side effects.

Administration through the skin using patches or creams. Limited use for peptides due to size, but GHK-Cu works topically.

A peptide consisting of three amino acids linked by two peptide bonds. GHK (glycyl-histidyl-lysine) is a well-known tripeptide used in skincare.

Peptides that affect blood vessel tone, causing vasodilation or vasoconstriction. Important in cardiovascular regulation and wound healing.

The World Anti-Doping Agency list of substances banned in competitive sports. BPC-157, TB-500, and growth hormone peptides are prohibited.