Glossary

Peptide & telehealth terms, defined

Plain-English definitions of the terms behind peptide therapy and telehealth, from GLP-1 and 503A compounding to half-life and evidence grades. 98 terms, each cross-linked.

Peptide Basics

Acetate Salt: Many peptides are supplied as an acetate salt, a stable form combined with acetic acid. Regulatory reviews often consider a peptide in both its free-base and acetate-salt forms.
Amino Acid: Amino acids are the building blocks of peptides and proteins. Chains of amino acids linked by peptide bonds form peptides; the specific sequence determines the molecule's shape and function.
Gastric Pentadecapeptide: A pentadecapeptide is a peptide made of 15 amino acids. BPC-157 is described as a gastric pentadecapeptide because it is a synthetic 15-amino-acid sequence derived from a protein found in gastric juice.
Human Growth Hormone (HGH)somatropin: Human growth hormone is a hormone that stimulates growth and cell repair. Synthetic HGH replaces the hormone directly, in contrast to secretagogues that stimulate the body's own release.
IGF-1Insulin-like Growth Factor 1: IGF-1 is a hormone produced mainly in the liver in response to growth hormone. It mediates many of growth hormone's effects, and its blood level is often used as a marker of GH activity.
Peptide: A peptide is a short chain of amino acids, typically between 2 and 50, that acts as a signaling molecule in the body. Peptides are smaller than proteins and can interact with specific receptors, which makes them useful as drugs.
Peptide Bond: A peptide bond is the chemical link that joins one amino acid to the next in a peptide or protein chain.
Polypeptide: A polypeptide is a single continuous chain of amino acids. The distinction between a long peptide and a small protein is not sharp; both are polypeptides.
Protein: A protein is a large molecule made of one or more long chains of amino acids. Proteins are generally bigger than peptides (often hundreds of amino acids) and fold into complex three-dimensional shapes.
Synthetic Peptide: A synthetic peptide is one manufactured in a lab rather than extracted from a natural source. Most therapeutic and research peptides are synthetic, produced to match a specific amino-acid sequence.

Mechanisms

Actin: Actin is a protein that forms part of the cell's internal scaffolding and is essential to cell movement. Regulating actin lets repair cells migrate to injured tissue.
Agonist: An agonist is a molecule that binds a receptor and activates it, producing a biological response. A receptor agonist mimics the natural signaling molecule for that receptor.
Angiogenesis: Angiogenesis is the formation of new blood vessels from existing ones. It supports healing by improving blood supply to tissue, and is the proposed mechanism behind some recovery peptides.
Antagonist: An antagonist binds a receptor without activating it, blocking the natural signaling molecule from acting. It is the functional opposite of an agonist.
Cell Migration: Cell migration is the movement of cells to a specific site, such as a wound, where they participate in repair. It depends on constant reorganization of the actin cytoskeleton.
Cytoprotective: Cytoprotective means protecting cells from damage. Some peptides are described as cytoprotective in animal studies of tissue injury.
Downregulation: Downregulation is a decrease in the number or sensitivity of receptors, often in response to constant stimulation. It is one reason some protocols cycle on and off.
GHRHGrowth-Hormone-Releasing Hormone: GHRH is the hormone that signals the pituitary gland to release growth hormone. GHRH analogs like sermorelin reproduce this signal to stimulate the body's own growth-hormone production.
GIPGlucose-dependent Insulinotropic Polypeptide: GIP is a second incretin hormone alongside GLP-1. Activating both the GIP and GLP-1 receptors is the basis of dual agonists like tirzepatide.
GLP-1Glucagon-like Peptide-1: GLP-1 is an incretin hormone released by the gut after eating. It boosts insulin release, slows stomach emptying, and reduces appetite. Drugs that activate its receptor drive weight loss and glucose control.
Growth Hormone Secretagogue: A growth hormone secretagogue is a compound that stimulates the body to release its own growth hormone, rather than supplying synthetic hormone. GHRH analogs are one type.
Incretin: Incretins are gut hormones, chiefly GLP-1 and GIP, released after eating that stimulate insulin secretion. Incretin mimetics are a major class of diabetes and weight-loss drugs.
Mitochondrial-Derived Peptide: A mitochondrial-derived peptide is encoded within mitochondrial DNA rather than the cell nucleus. MOTS-c is an example, studied as a metabolic signaling molecule.
Nitric Oxide: Nitric oxide is a small signaling molecule that relaxes blood vessels and is involved in blood flow and healing. Several peptides are proposed to act partly through nitric-oxide pathways.
Receptor: A receptor is a protein, usually on a cell surface, that a signaling molecule binds to in order to trigger an effect inside the cell. Peptide drugs work by binding specific receptors.
Telomerase: Telomerase is the enzyme that rebuilds telomeres. Activating it is the proposed longevity mechanism for some peptides, but because many cancers rely on telomerase, activating it raises a safety question.
Telomere: Telomeres are protective caps at the ends of chromosomes that shorten each time a cell divides. When they become too short, the cell stops dividing, a process tied to cellular aging.
Tolerance: Tolerance is a reduced response to a substance after repeated exposure, so a larger dose is needed for the same effect. It can involve receptor downregulation.
VEGFVascular Endothelial Growth Factor: VEGF is a signaling protein that promotes the growth of new blood vessels (angiogenesis). Some peptides are proposed to influence VEGF signaling to support tissue repair.

Administration

Bacteriostatic Water: Bacteriostatic water is sterile water containing a small amount of preservative (benzyl alcohol) that inhibits bacterial growth. It is commonly used to reconstitute peptides for multi-dose use.
Injection Site: The injection site is the body location where an injection is given, such as the abdomen or thigh. Rotating sites helps reduce local irritation.
Insulin Syringe: An insulin syringe is a small syringe with a fine, short needle used for subcutaneous injections, commonly used for peptides and GLP-1 medications.
Intramuscular InjectionIM: An intramuscular injection delivers a medication into a muscle, which absorbs some drugs differently than subcutaneous tissue.
Loading Dose: A loading dose is a higher initial dose used to reach an effective level quickly, sometimes followed by a lower maintenance dose. Loading protocols for research peptides are community practice, not established science.
Lyophilizedfreeze-dried: Lyophilized means freeze-dried. Peptides are often supplied as a lyophilized powder for stability and reconstituted into liquid before use.
Maintenance Dose: A maintenance dose is the ongoing dose used to sustain an effect after any initial titration or loading phase.
Nasal Spray: A nasal spray delivers a medication through the lining of the nose. Some peptides are formulated as nasal sprays as a needle-free route.
Reconstitution: Reconstitution is the process of mixing a freeze-dried (lyophilized) peptide powder with a sterile liquid to create an injectable solution.
Sterile: Sterile means free of living microorganisms. Injectable products must be sterile, which is one reason unregulated research-chemical vials carry risk.
Subcutaneous InjectionSubQ, SC: A subcutaneous injection delivers a medication into the fatty layer just under the skin. Most injectable peptides and GLP-1 drugs are given this way.
Titration: Titration is the gradual adjustment of a dose, usually starting low and increasing over time. GLP-1 drugs are titrated slowly to limit gastrointestinal side effects.
Troche: A troche is a small lozenge that dissolves in the mouth, allowing a medication to absorb through the oral tissues rather than being swallowed.

Pharmacology

Adverse Event: An adverse event is any undesirable medical occurrence during treatment, whether or not it is proven to be caused by the drug. Reports are collected in systems like FAERS.
Bioavailability: Bioavailability is the proportion of a dose that reaches the bloodstream in active form. Many peptides have low oral bioavailability, which is why they are injected.
Boxed Warningblack box warning: A boxed warning is the FDA's strongest warning on a drug label, highlighting a serious or life-threatening risk. GLP-1 drugs carry one for thyroid C-cell tumors seen in rodents.
Contraindication: A contraindication is a specific situation in which a drug should not be used because the risk outweighs the benefit. For example, GLP-1 drugs are contraindicated with a history of medullary thyroid carcinoma.
Dose-Response: A dose-response relationship describes how the effect of a drug changes with dose. Establishing it in humans requires dose-finding trials, which most research peptides lack.
Efficacy: Efficacy is the maximum effect a drug can produce under ideal (trial) conditions. It differs from effectiveness, which is the effect under real-world use.
FAERSFDA Adverse Event Reporting System: FAERS is the FDA's database of adverse-event and medication-error reports. Signals in FAERS can prompt further review, though a report alone does not prove causation.
Half-Life: A drug's half-life is the time it takes for its concentration in the body to fall by half. It largely determines how often a drug is dosed.
Off-Label Use: Off-label use is prescribing an approved drug for a purpose, dose, or population not specified in its FDA labeling. It is legal and common but not FDA-reviewed for that use.
PharmacodynamicsPD: Pharmacodynamics is the study of a drug's effects on the body and how it produces them, in short, what the drug does to the body.
PharmacokineticsPK: Pharmacokinetics is the study of how the body absorbs, distributes, metabolizes, and eliminates a drug, in short, what the body does to the drug.
Potency: Potency describes how much of a drug is needed to produce an effect. A more potent drug achieves the same effect at a lower dose.

Regulatory & Compounding

503A Bulks List: The 503A Bulks List is the FDA's roster of bulk drug substances that 503A pharmacies may compound without an FDA-approved product. A non-approved peptide must be on it to be compounded legally.
503A Compounding: Section 503A covers traditional pharmacies that compound patient-specific prescriptions. They may use a bulk substance only if it is FDA-approved, in a USP monograph, or on the 503A Bulks List.
503B Outsourcing Facility: Section 503B covers registered outsourcing facilities that compound larger batches under stricter manufacturing standards, using their own separate bulks list.
Bulk Drug Substance: A bulk drug substance is the active pharmaceutical ingredient used in compounding, before it is made into a finished medication. Each is evaluated individually for the bulks list.
Compounding Pharmacy: A compounding pharmacy prepares customized medications for patients who cannot use a standard commercial product, within the limits set by Sections 503A and 503B.
Controlled Substance: A controlled substance is a drug regulated under the Controlled Substances Act because of abuse or dependence risk, scheduled I through V and overseen by the DEA. The peptides discussed here are generally not controlled substances.
DEADrug Enforcement Administration: The DEA is the U.S. agency that enforces controlled-substance laws, including the scheduling and prescribing rules for controlled drugs.
Drug Shortage: An official FDA drug shortage can temporarily permit compounding of a copy of an otherwise-commercial drug. Compounded semaglutide and tirzepatide access hinged on shortage status.
FDAU.S. Food and Drug Administration: The FDA is the U.S. agency that regulates drugs, including approvals, labeling, safety monitoring, and the rules governing compounding.
FDA-Approved: An FDA-approved drug has been reviewed and cleared by the FDA as safe and effective for a specific use, based on clinical trial evidence. Most research peptides are not FDA-approved.
GMP / cGMPGood Manufacturing Practice: Good Manufacturing Practice is the set of quality standards for how drugs are produced. Current GMP (cGMP) applies to registered manufacturers and 503B outsourcing facilities.
Investigational New Drug (IND): An IND is the FDA authorization that allows an experimental drug to be tested in humans. It precedes the clinical trials needed for approval.
New Drug Application (NDA): An NDA is the formal application a company submits to the FDA to market a new drug, containing the trial evidence for safety and effectiveness.
PCACPharmacy Compounding Advisory Committee: The PCAC is the FDA advisory committee that reviews nominated substances against the statutory criteria and votes on whether to recommend adding them to the 503A Bulks List. Its votes are advisory.
PrescriptionRx: A prescription is an order from a licensed clinician authorizing a specific medication for a patient. Compounded peptides require a valid prescription.
Prior Authorization: Prior authorization is a requirement that an insurer approve a medication before it will cover it. It commonly applies to GLP-1 weight-loss drugs.
Research Chemicalnot for human use: A research chemical is a substance sold labeled 'not for human use,' outside the regulated supply chain, with no prescription, pharmacy oversight, or guaranteed testing. Much of the gray-market peptide supply is sold this way.
USPUnited States Pharmacopeia: The USP sets public quality standards for medicines. A substance with a USP monograph has an official quality standard, which is one pathway for use in compounding.

Clinical Evidence

Clinical Trial: A clinical trial is a research study testing a treatment in people. Trials progress through phases, from small safety studies to large effectiveness studies.
Clinical Trial Phases: Clinical trials run in phases: Phase 1 tests safety in a small group, Phase 2 tests early effectiveness and dose, and Phase 3 confirms effectiveness in large groups before approval.
Dose-Finding Trial: A dose-finding trial identifies the dose that balances effect and safety in humans. The lack of dose-finding trials is a key gap for most research peptides.
Efficacy vs Effectiveness: Efficacy is how well a drug works under ideal trial conditions; effectiveness is how well it works in real-world use. Real-world results are often smaller than trial results.
Endpoint: An endpoint is the specific outcome a trial measures, such as body-weight change or cardiovascular events. Hard endpoints (like heart attacks) carry more weight than surrogate markers.
Evidence Grade: An evidence grade rates how strong the human evidence for a compound is. TeleRanked uses an A-E scale, from FDA-approved (A) down to anecdotal (E), based on trial quality rather than popularity.
In Vitro: In vitro means 'in glass,' referring to experiments done in cells or test tubes outside a living organism.
In Vivo: In vivo means 'within the living,' referring to experiments done in a whole living organism, such as an animal study.
Meta-Analysis: A meta-analysis statistically combines results from multiple studies to reach a more precise overall conclusion. With systematic reviews, it sits near the top of the evidence hierarchy.
Peer Review: Peer review is the evaluation of research by independent experts before publication. Peer-reviewed sources are more reliable than unreviewed claims.
Placebo: A placebo is an inactive treatment used as a comparison in trials, so a drug's effect can be separated from expectation and natural change.
PMIDPubMed ID: A PMID is the unique identifier for a specific article in PubMed, used to cite the exact study behind a claim.
Preclinical: Preclinical research is done before human testing, in cells (in vitro) or animals (in vivo). Promising preclinical results often do not translate to humans, which is why they are graded cautiously.
PubMed: PubMed is a free database of biomedical literature maintained by the U.S. National Library of Medicine, widely used to find peer-reviewed studies.
Randomized Controlled Trial (RCT): An RCT randomly assigns participants to a treatment or a control group, which is the strongest design for showing a drug actually works. Most research peptides lack a completed human RCT.
Systematic Review: A systematic review comprehensively gathers and appraises all studies on a question using a defined method, reducing bias compared with a casual literature summary.

Anti-Doping

Performance-Enhancing Drug (PED): A performance-enhancing drug is a substance used to improve athletic performance. Many peptides marketed for recovery or growth fall under anti-doping rules.
Therapeutic Use Exemption (TUE): A TUE is an approval that lets an athlete use an otherwise-prohibited substance for a legitimate medical reason, under defined conditions.
WADAWorld Anti-Doping Agency: WADA is the international body that sets anti-doping rules for sport and publishes the Prohibited List. Several peptides, including TB-500 and MOTS-c, are prohibited.
WADA Prohibited List: The Prohibited List is WADA's annually updated list of substances and methods banned in sport. It includes a category for non-approved substances, which captures many research peptides.

Metabolic & Weight

BMIBody Mass Index: BMI is a weight-to-height ratio used to categorize underweight, normal weight, overweight, and obesity. It is a screening tool, not a direct measure of body fat or health.
Gastric Emptying: Gastric emptying is the rate at which food leaves the stomach. GLP-1 drugs slow it, prolonging fullness, which also contributes to nausea during dose escalation.
Insulin Resistance: Insulin resistance is a reduced response of cells to insulin, so the body needs more of it to control blood sugar. It underlies type 2 diabetes and is a target of incretin drugs.
Obesity: Obesity is a chronic condition of excess body fat, commonly defined by a BMI of 30 or higher, associated with increased health risks. It is an approved indication for drugs like semaglutide and tirzepatide.
Satiety: Satiety is the feeling of fullness that reduces further eating. GLP-1 drugs increase satiety, which is part of how they reduce food intake.
Type 2 Diabetes: Type 2 diabetes is a chronic condition of high blood sugar driven largely by insulin resistance. GLP-1 and dual agonists are approved to treat it.