The medical peptide glossary.

5-Amino-1MQ

A small-molecule NNMT inhibitor that increases cellular NAD+ and β-hydroxybutyrate — investigational for metabolic health and fat-loss support.

503A Pharmacy

A US compounding pharmacy that prepares medications for individual patients based on a specific prescription.

β3-AdrenoceptorBeta-3 Adrenergic Receptor

A receptor on fat cells whose activation triggers lipolysis — the target of peptides like AOD-9604.

A13 TERMS

Adiponectin

An adipokine with insulin-sensitising and anti-inflammatory effects — falls as visceral adiposity rises.

Adipose Tissue

Fat tissue — composed of adipocytes storing triglycerides, plus immune and vascular cells — the target of lipolytic peptides.

Adverse Event

Any unfavourable medical occurrence during treatment — reported to the clinician regardless of whether a direct link is suspected.

Agonist

A molecule that binds a receptor and triggers its activity — most therapeutic peptides are agonists of a specific endogenous receptor.

Amino Acid

The molecular building block of peptides and proteins — 20 standard amino acids link together via peptide bonds to form larger chains.

AMPKAMP-Activated Protein Kinase

The cellular energy sensor that triggers fat burning, glucose uptake and mitochondrial biogenesis when ATP runs low — activated by MOTS-c.

Amylin

A pancreatic peptide co-secreted with insulin that slows gastric emptying and reduces glucagon

Angiogenesis

The formation of new blood vessels from existing vasculature — the core repair mechanism BPC-157 accelerates via VEGF.

Antagonist

A molecule that binds a receptor and blocks its activation — used therapeutically to silence an over-active signalling pathway.

AOD-9604AOD9604

A modified fragment of human growth hormone (amino acids 177–191) that stimulates fat metabolism without affecting blood glucose or IGF-1.

APIActive Pharmaceutical Ingredient

The biologically active component of a medication — the specific peptide itself, before formulation.

ApoBApolipoprotein B

The primary atherogenic protein in blood — a better cardiovascular-risk marker than LDL alone.

Autophagy

The cellular self-cleaning process that recycles damaged organelles and proteins — a core longevity mechanism activated by fasting, exercise and certain peptides.

B6 TERMS

Bacteriostatic Water

Sterile water with 0.9% benzyl alcohol preservative — the diluent used to reconstitute lyophilised peptide vials.

Bioavailability

The fraction of a dose that reaches circulation in active form — a key reason most peptides are injected subcutaneously rather than taken orally.

A measurable substance in blood, tissue or urine that reflects a biological state — the inputs your clinician uses to choose the right protocol.

BMIBody Mass Index

A screening calculation (weight/height²) used to categorise body size — useful at population level, crude at the individual level.

BPC-157Body Protection Compound 157

A 15-amino-acid peptide derived from a protein in human gastric juice, studied for gut-lining repair and soft-tissue healing.

Bulks List

The FDA's list of substances permitted for compounding under Section 503A — the list that determines which peptides are legally compoundable.

C12 TERMS

CagriSema

A dual-peptide combination of cagrilintide (amylin analog) and semaglutide (GLP-1 agonist) — investigational for weight management.

CBCComplete Blood Count

A foundational blood test measuring red cells, white cells, platelets and haemoglobin — used as a safety baseline before most peptide protocols.

Cerebrolysin

A complex of neurotrophic peptides derived from porcine brain tissue — used clinically in Europe and Asia for stroke and cognitive-decline indications.

cGMPCurrent Good Manufacturing Practice

FDA-enforced manufacturing standards for pharmaceutical products. 503A compounders operate under USP 795/797 standards rather than full cGMP.

Circadian Rhythm

The body's ~24-hour biological clock that governs sleep, hormone release and cellular repair

CJC-1295CJC-1295 no-DAC

A GHRH analog that extends the body's natural growth-hormone pulses — typically paired with Ipamorelin for muscle preservation and sleep quality.

CMPComprehensive Metabolic Panel

A 14-marker blood panel measuring glucose, electrolytes, kidney and liver function — standard safety work before most protocols.

Cold Chain

Refrigerated shipping and storage throughout the supply chain — required for most lyophilised peptides to preserve potency.

Collagen Synthesis

The biological process of producing collagen — accelerated by peptides like GHK-Cu and BPC-157 during tissue repair.

Compounded Peptide

A peptide prepared for an individual patient by a licensed compounding pharmacy, prescribed by a clinician and tested for identity, potency and contamination.

Contraindication

A specific circumstance in which a medication should not be used — the list of 'if this, then no' conditions for each protocol.

Cortisol

The body's primary stress hormone, secreted by the adrenals under HPA-axis control — one thing Ipamorelin specifically does not raise.

D6 TERMS

DEXA ScanDXA

A low-radiation scan that maps body composition into lean mass, fat mass and bone density — the clinical gold standard for tracking peptide outcomes.

DHEA-SDehydroepiandrosterone Sulfate

An adrenal steroid that declines steadily with age — a sensitive marker of adrenal-reserve capacity and biological-age metrics.

Dose Titration

Gradually increasing a peptide dose from a low starting point — standard practice for GLP-1s, GHRH analogs and any protocol with GI or tolerance profiles.

Drug Interaction

An effect of one medication on the metabolism, absorption or action of another — why your clinician reviews your full medication list.

DSIPDelta Sleep-Inducing Peptide

A nine-amino-acid peptide studied for sleep architecture, particularly for deep (delta-wave) sleep restoration.

Dyslipidemia

Abnormal blood lipid levels — elevated ApoB, LDL or triglycerides, or low HDL. A core cardiovascular-risk axis.

E4 TERMS

Endocrinology

The medical specialty concerned with hormones and the glands that secrete them — the parent discipline for peptide and metabolic medicine.

Endotoxin

A bacterial cell-wall fragment that can contaminate injectables — tested for in every batch of a compounded peptide.

EpitalonEpithalon

A four-amino-acid peptide that upregulates telomerase activity and restores pineal circadian signalling — typically cycled 10 days, quarterly.

EstradiolE2

The primary circulating estrogen — central to reproductive, bone, cardiovascular and cognitive health in both sexes.

F11 TERMS

Fasting Glucose

Blood glucose measured after an 8-hour fast — the simplest metabolic-safety screen before any GH-axis or GLP-1 protocol.

Fasting Insulin

Insulin measured after an 8-hour fast — a sensitive early marker of insulin resistance.

FDAFood and Drug Administration

The US regulatory body for drugs, devices and compounding pharmacies — the agency that classifies which peptides may be compounded.

Ferritin

The body's iron storage protein — low values indicate depletion, high values often reflect inflammation rather than iron overload.

First-Pass Metabolism

The breakdown of an orally administered drug by the gut and liver before it reaches systemic circulation — the reason most peptides are injected.

FollistatinFollistatin 344

A naturally occurring protein that binds and inhibits myostatin — theoretically permitting greater muscle hypertrophy.

Food Noise

The intrusive mental chatter about food that GLP-1 receptor agonists quiet — a widely reported but underdocumented effect.

Fragment 176-191HGH Frag 176-191

A fragment of human growth hormone (amino acids 176–191) with lipolytic activity — an older relative of AOD-9604.

Frailty

A clinical syndrome of reduced reserve and increased vulnerability — the downstream consequence of unchecked sarcopenia and age-related decline.

Free T3Free Triiodothyronine

The bioactive thyroid hormone — small changes have outsized clinical effects.

Free T4Free Thyroxine

The unbound, bioavailable fraction of thyroxine — the main circulating thyroid hormone.

G10 TERMS

Gastric Emptying

The rate at which food exits the stomach — slowed by GLP-1 receptor agonists, which extends satiety but can also cause nausea.

GHK-CuCopper Tripeptide-1

A naturally occurring copper-binding tripeptide that activates tissue-repair gene programs and collagen synthesis — used topically and injected.

Ghrelin

The 'hunger hormone' secreted by the stomach — its receptor is the target of GH secretagogues like Ipamorelin.

GHRH AnalogGrowth-Hormone-Releasing Hormone Analog

A class of peptides that mimic growth-hormone-releasing hormone at the pituitary to trigger the body's own GH release — CJC-1295, Tesamorelin and Sermorelin.

GHRP-2

An older-generation GH secretagogue — active but less selective than Ipamorelin, rarely chosen in modern clinical protocols.

GHRP-6

Another older-generation GH secretagogue with strong appetite-stimulating activity — largely superseded by Ipamorelin in clinical use.

GIPGlucose-Dependent Insulinotropic Polypeptide

An incretin hormone released by gut K-cells after a meal — the second receptor targeted by tirzepatide, on top of GLP-1.

GLP-1 Receptor AgonistGLP-1 RA

A peptide drug class that mimics glucagon-like peptide-1 to slow gastric emptying, sharpen insulin response and quiet food-noise.

GonadorelinGnRH analog

A synthetic analog of gonadotropin-releasing hormone — used to support testicular function during TRT or fertility protocols.

Growth HormoneGH

A pituitary-secreted hormone that drives protein synthesis, fat metabolism and tissue repair — released in pulses, peaking at night.

H10 TERMS

Half-Lifet½

The time required for a drug's plasma concentration to drop by half — a key determinant of dosing frequency.

HbA1cGlycated Haemoglobin

A blood marker of average glucose over the prior 3 months — the standard metric for diabetes screening and GH-axis protocol safety.

HDL CholesterolHigh-Density Lipoprotein

The cholesterol carried on high-density lipoproteins — associated with cardiovascular protection but no longer directly targetable.

Hexarelin

A potent GH secretagogue — more powerful than Ipamorelin but with less selectivity, so less often chosen in modern protocols.

HOMA-IRHomeostatic Model Assessment of Insulin Resistance

A calculated insulin-resistance score from fasting glucose and fasting insulin — a sensitive early metabolic-dysfunction marker.

Homocysteine

An amino-acid metabolite — elevated values indicate B-vitamin deficiency and are an independent cardiovascular risk marker.

HPA AxisHypothalamic-Pituitary-Adrenal Axis

The feedback loop between hypothalamus, pituitary and adrenals that governs cortisol and stress response.

hs-CRPHigh-Sensitivity C-Reactive Protein

A sensitive inflammation marker — elevated values change which peptides a clinician selects and at what dose.

Hypertension

Persistently elevated blood pressure — 130/80 mmHg and above by current US guidelines.

Hypothalamus

The brain region that integrates endocrine, autonomic and behavioural signals — the command centre of the HPA, HPG and HP-thyroid axes.

I10 TERMS

IGF-1Insulin-like Growth Factor 1

The primary blood marker of growth-hormone activity — the lab that gates any GH-axis protocol and the one re-checked at month 3.

IGF-1 LR3Long R3 IGF-1

A modified, long-acting variant of IGF-1 with reduced binding-protein affinity — potent but with a serious safety profile for most use-cases.

Incretin

A gut hormone released after a meal that amplifies insulin secretion — the hormonal family targeted by semaglutide and tirzepatide.

Inflammation

The body's protective response to injury or infection — helpful acutely, destructive when chronic, and a major target of several peptides.

Injection Site Rotation

The practice of varying subcutaneous injection location across sessions to prevent lipoatrophy and injection-site reactions.

Insulin Sensitivity

How effectively cells respond to insulin — improved by exercise, GLP-1s, MOTS-c and most metabolic peptides.

Insulin Syringe

The 30–31-gauge syringe calibrated in insulin units — the standard tool for subcutaneous peptide self-injection.

Intramuscular InjectionIM Injection

Injection into muscle tissue — faster absorption than subcutaneous, used for specific peptides and hormone therapies.

Intranasal Administration

Delivery via the nasal mucosa — used for peptides like Selank, Semax and certain oxytocin protocols where CNS access matters.

Ipamorelin

A selective growth-hormone secretagogue that triggers GH release without spiking cortisol or prolactin — usually paired with CJC-1295.

K2 TERMS

Kisspeptin

A hypothalamic peptide that triggers GnRH release — the upstream switch of the entire reproductive hormone axis.

KPVLysine-Proline-Valine

The C-terminal tripeptide of α-MSH with strong anti-inflammatory activity, particularly at mucosal surfaces — gut and skin.

L9 TERMS

LDL CholesterolLow-Density Lipoprotein

The cholesterol carried on low-density lipoproteins — the traditional cardiovascular-risk marker, increasingly supplemented by ApoB.

Leptin

A hormone secreted by fat cells that signals energy stores to the brain — dysfunctional in most obesity and blunted by chronic inflammation.

Leptin Resistance

The state in which elevated leptin levels fail to suppress appetite — a core mechanism of obesity and metabolic syndrome.

Lipolysis

The biological breakdown of stored fat into free fatty acids — the mechanism targeted by AOD-9604 and Tesamorelin.

LiraglutideSaxenda

A once-daily GLP-1 receptor agonist — the older-generation alternative to semaglutide, with a shorter half-life and daily dosing.

Liver Function TestsLFTs

Blood tests measuring hepatic enzymes (ALT, AST, ALP) and bilirubin — reviewed before starting protocols with liver exposure.

LL-37Cathelicidin

A naturally occurring human antimicrobial peptide with broad-spectrum activity and immune-modulating effects.

Longevity

The domain of medicine focused on healthspan and the biology of aging — the central interest behind NAD+, Epitalon and MOTS-c.

LyophilisationFreeze-Drying

The freeze-drying process used to stabilise peptides for shipping — the vial you reconstitute with bacteriostatic water on arrival.

M7 TERMS

Melanotan IIMT-II

A melanocortin agonist originally studied for skin pigmentation as a photoprotective agent — not part of the Meto catalogue for safety reasons.

Melatonin

The hormone secreted by the pineal gland at night that regulates sleep-wake timing — downstream of circadian-active peptides.

Metabolic Syndrome

A cluster of five conditions — central obesity, hypertension, dyslipidaemia, hyperglycaemia, low HDL — that together multiply cardiovascular risk.

MGFMechano Growth Factor

A splice variant of IGF-1 released by mechanically stressed muscle — studied for satellite-cell activation and localised muscle repair.

Mitochondria

The cellular organelles that produce ATP — the direct target of NAD+ supplementation and mitochondrial peptides like MOTS-c.

MOTS-cMitochondrial Open Reading Frame of 12S rRNA type-c

A 16-amino-acid peptide encoded in mitochondrial DNA that improves insulin sensitivity and cellular energy output.

mTORMechanistic Target of Rapamycin

A master growth-signalling kinase that integrates nutrient, energy and hormonal cues — the counterweight to autophagy in longevity biology.

N3 TERMS

NAD+Nicotinamide Adenine Dinucleotide

A co-enzyme every cell uses to make energy. Levels drop ~50% by age 60; injected NAD+ restores the baseline.

NAFLD / MASLDNon-alcoholic Fatty Liver Disease

Fat accumulation in the liver driven by metabolic dysfunction — renamed MASLD in 2023 to reflect the central role of metabolism.

Nitric OxideNO

A signalling molecule that regulates blood flow and tissue repair — modulated by BPC-157 at the gut lining and injury sites.

O2 TERMS

Oral Bioavailability

The fraction of an orally taken drug that survives digestion and reaches circulation — typically under 1% for peptides.

Oxytocin

A naturally occurring nine-amino-acid peptide hormone that governs social bonding, childbirth and lactation — used clinically in specific compounded contexts.

P9 TERMS

Peptide

A short chain of amino acids — longer than a single amino acid, shorter than a full protein — that acts as a precise biological signal.

Peptide Bond

The covalent link between two amino acids — the chemistry that defines every peptide and protein.

Peptide Readiness Panel

Meto's $149 lab panel covering the biomarkers needed to match a patient to the right peptide protocol safely.

PharmacodynamicsPD

What a drug does to the body — the receptor binding and downstream signalling that produce the clinical effect.

PharmacokineticsPK

What the body does to a drug — absorption, distribution, metabolism and excretion. The science of dose-to-plasma-level relationships.

Pineal Gland

A small endocrine gland in the brain that secretes melatonin — the anatomical origin of Epitalon's developmental story.

Pituitary Gland

The 'master gland' at the base of the brain that secretes growth hormone, ACTH, TSH and other downstream hormones.

Prediabetes

Elevated blood glucose below the diabetic threshold — HbA1c 5.7-6.4% or fasting glucose 100-125 mg/dL. Reversible with lifestyle or medication.

PT-141Bremelanotide

A melanocortin-receptor agonist used for sexual-function support — FDA-approved as Vyleesi for acquired hypoactive sexual desire disorder in women.

R4 TERMS

Receptor Binding

The molecular interaction between a drug and its receptor — the first step in pharmacodynamics and the determinant of specificity.

Reconstitution

Mixing bacteriostatic water into a freeze-dried peptide vial to create a usable solution — the step every member does on arrival.

Research Chemical

Unregulated peptides sold online labelled 'not for human use' — not a legitimate prescription pathway and not tested for patient safety.

Retatrutide

A next-generation triple agonist targeting GLP-1, GIP and glucagon receptors — the most effective weight-management peptide seen in phase-2 trials.

S13 TERMS

Sarcopenia

Age-related loss of muscle mass and function — the silent metabolic disease that undermines most other longevity efforts.

Selank

A synthetic neuropeptide with anxiolytic and pro-cognitive effects — administered intranasally or as oral drops.

SemaglutideOzempic

A long-acting GLP-1 receptor agonist used for type-2 diabetes and chronic weight management — the active ingredient in Ozempic and Wegovy.

Semax

A Russian-developed cognitive peptide used clinically for stroke recovery and ADHD — a BDNF-potentiating nootropic with an anxiolytic edge.

Senescence

The cellular state of permanent growth arrest with secretion of pro-inflammatory signals — a central driver of biological aging.

Senolytic

A class of therapies that selectively eliminate senescent cells — an emerging longevity approach, mostly small-molecule rather than peptide.

Sermorelin

A native GHRH analog — the gentlest and most-studied entry point into growth-hormone-axis therapy.

SHBGSex Hormone-Binding Globulin

A hepatic protein that binds testosterone and estradiol — affects how much hormone is bioavailable and how lab values are interpreted.

Sirtuins

A family of NAD+-dependent enzymes that regulate metabolism, stress response and aging

Sleep Architecture

The pattern of sleep stages across the night — deep sleep, REM and light sleep cycles.

Somatostatin

A hypothalamic peptide that inhibits growth-hormone release — the brake that balances the GHRH accelerator.

SS-31Elamipretide

A mitochondria-targeted peptide that stabilises cardiolipin and restores mitochondrial function in stressed cells.

Subcutaneous InjectionSQ Injection

Injection into the fatty layer just below the skin — the standard route for peptide dosing, self-administered with an insulin syringe.

T13 TERMS

TB-500Thymosin Beta-4

A synthetic fragment of Thymosin-β4 that accelerates cellular migration to damaged tissue — the recovery-focused partner to BPC-157.

Telehealth Prescribing

Prescription of a medication after a virtual clinician encounter — the legal framework under which Meto operates.

Telomerase

The enzyme that maintains telomere length at chromosome ends — upregulated by Epitalon in longevity cycles.

Telomere

The protective DNA cap at the end of each chromosome — shortens with age and each cell division.

Tesamorelin

A stabilised GHRH analog with FDA approval for visceral-fat reduction in HIV-associated lipodystrophy — increasingly used off-label for metabolic syndrome.

Testosterone

The primary male androgen — measured as total and free fractions. Low levels in men drive the TRT decision; in women, context is everything.

Thymosin α-1Thymalfasin

A 28-amino-acid peptide produced by the thymus that modulates T-cell balance and NK-cell activity — used clinically in 30+ countries.

Thymosin β-4Tβ4

The parent peptide behind TB-500 — a 44-amino-acid naturally occurring actin-regulating peptide studied for systemic repair.

Thyroid AxisHypothalamic-Pituitary-Thyroid Axis

The feedback loop between hypothalamus (TRH), pituitary (TSH) and thyroid (T4, T3) — governs metabolic rate across tissues.

TirzepatideMounjaro

A dual GLP-1 and GIP receptor agonist — the most effective FDA-approved weight-management peptide to date, the active ingredient in Mounjaro and Zepbound.

Titration

See Dose Titration — the staged escalation of a peptide dose from a low starting point to the target therapeutic dose.

Triglycerides

Blood fats that reflect dietary and metabolic patterns — elevated values are a sensitive early marker of insulin resistance.

TSHThyroid-Stimulating Hormone

The pituitary hormone that drives thyroid output — the primary screening test for thyroid function.

U1 TERM

USP 797 / USP 795

Pharmacopoeial standards governing sterile (USP 797) and non-sterile (USP 795) compounding

V3 TERMS

VEGFVascular Endothelial Growth Factor

A signalling protein that drives the growth of new blood vessels — the primary mechanism behind BPC-157's tissue-repair effects.

Visceral FatVisceral Adipose Tissue

Fat stored around internal organs — metabolically active, tied to cardiovascular risk, and the target of Tesamorelin and SCULPT.

Vitamin D25-hydroxy Vitamin D

A fat-soluble vitamin that functions more like a hormone — widely deficient, with broad effects on immune, bone and metabolic health.

W3 TERMS