Reference

Glossary

The vocabulary of peptides, GLP-1 medications, and longevity — defined in plain language, with the evidence caveats that matter. A reference, not medical advice.

GLP-1

GLP-1: Glucagon-like peptide-1, a gut hormone (incretin) released after eating that boosts insulin, slows stomach emptying, and reduces appetite. The target of semaglutide and related drugs.
GLP-1 receptor agonist: A medication that activates the GLP-1 receptor to mimic the natural hormone — lowering blood sugar and appetite. Examples: semaglutide, liraglutide.
GIP: Glucose-dependent insulinotropic polypeptide, a second incretin hormone. Tirzepatide activates both GIP and GLP-1 receptors (a 'dual agonist').
Incretin: A gut hormone (GLP-1 and GIP) secreted in response to food that stimulates insulin release. 'Incretin mimetics' are drugs that copy this effect.
Semaglutide: A GLP-1 receptor agonist sold as Ozempic and Rybelsus (diabetes) and Wegovy (weight management); also widely compounded.
Tirzepatide: A dual GIP/GLP-1 receptor agonist sold as Mounjaro (diabetes) and Zepbound (weight management).
Retatrutide: An investigational 'triple agonist' targeting GIP, GLP-1, and glucagon receptors, in late-stage obesity trials as of 2026.
Orforglipron: An investigational once-daily oral, non-peptide ('small molecule') GLP-1 receptor agonist — notable for not requiring injection or strict fasting like oral semaglutide.
Cagrilintide: A long-acting amylin analog studied for weight loss, including in combination with semaglutide (CagriSema).
MACE: Major adverse cardiovascular events — a composite trial endpoint (typically cardiovascular death, heart attack, stroke) used to measure a drug's effect on heart risk.
Ozempic: The brand of injectable semaglutide approved for type-2 diabetes (and to reduce cardiovascular risk). The weight-loss brand of the same molecule is Wegovy.
Wegovy: The brand of semaglutide 2.4 mg approved specifically for chronic weight management — the same molecule as Ozempic at a higher dose ceiling.
Mounjaro: The brand of tirzepatide approved for type-2 diabetes. The same molecule is sold as Zepbound for weight management.
Zepbound: The brand of tirzepatide approved for weight management (and for obstructive sleep apnea with obesity) — identical molecule to Mounjaro.
Rybelsus: Oral semaglutide, a daily tablet for type-2 diabetes. It must be taken on an empty stomach with a small sip of water, then 30 minutes before food.
Saxenda: The brand of liraglutide 3.0 mg, a once-daily injectable approved for weight management — an older, less potent GLP-1 than Wegovy.
Liraglutide: A once-daily GLP-1 receptor agonist (Victoza for diabetes, Saxenda for weight) — shorter-acting and less potent than weekly semaglutide.
Dulaglutide: A once-weekly GLP-1 receptor agonist sold as Trulicity for type-2 diabetes; outperformed by semaglutide in the SUSTAIN-7 head-to-head trial.
Contrave: An oral weight-loss pill combining naltrexone and bupropion that targets appetite and food reward — far less potent than GLP-1 drugs (~6% vs ~15% weight loss).
Amylin: A pancreatic hormone, co-released with insulin, that reduces appetite and slows gastric emptying. Cagrilintide is a long-acting amylin analog.
Glucagon: A hormone that raises blood sugar and increases energy expenditure. 'Triple agonists' like retatrutide add glucagon-receptor activity to GIP and GLP-1.
HbA1c: Glycated hemoglobin — a blood marker reflecting average glucose over ~3 months. The primary endpoint in most diabetes drug trials.
Gastroparesis: Delayed stomach emptying. GLP-1 drugs slow gastric emptying by design, which drives nausea and, rarely, more significant motility problems.
Ozempic face: Facial volume and skin laxity from rapid weight loss — not a drug-specific effect, but a consequence of losing fat quickly at any cause.
Food noise: The intrusive, persistent thoughts about food that many people report, and that GLP-1 drugs are described as quieting.
BMI: Body mass index (weight ÷ height²). Weight-loss drugs are typically approved for BMI ≥30, or ≥27 with a weight-related condition.
CagriSema: An investigational fixed-dose combination of cagrilintide (an amylin analog) and semaglutide, studied for weight loss in the REDEFINE program.
MASH (NASH): Metabolic dysfunction-associated steatohepatitis (formerly NASH) — an advanced fatty-liver disease. Semaglutide showed benefit in trials, and Wegovy gained a MASH indication.
Compounded tirzepatide: Tirzepatide mixed by a compounding pharmacy rather than the manufacturer. Not FDA-approved, with a legal pathway that narrowed after the shortage ended.
GLP-1 microdosing: Using sub-therapeutic GLP-1 doses below the labeled range — a marketing trend rather than a protocol with outcome-trial evidence behind it.
Pancreatitis: Inflammation of the pancreas — a rare labeled risk for GLP-1 drugs and a reason to stop the medication if suspected.
Sarcopenia: Loss of muscle mass and strength. Because rapid GLP-1 weight loss includes some lean-mass loss, preserving muscle (protein, resistance training) is a common concern.
Lipodystrophy: Abnormal body-fat distribution. HIV-associated lipodystrophy is the specific condition tesamorelin (Egrifta) is FDA-approved to treat.
Weight set point: The body weight the brain defends through hunger and metabolism. GLP-1 drugs appear to lower it, which is why weight often returns when they're stopped.
Dual agonist: A single molecule that activates two receptors at once. Tirzepatide (GIP + GLP-1) is the approved example; survodutide, mazdutide and pemvidutide pair GLP-1 with the glucagon receptor.
Triple agonist: A single molecule hitting three receptors — GIP, GLP-1 and glucagon. Retatrutide is the lead example, with the largest weight-loss figures reported so far, though still investigational.
Oxyntomodulin: A natural gut hormone that activates both the GLP-1 and glucagon receptors — the biological template for GLP-1/glucagon dual agonists like mazdutide.
Survodutide: An investigational once-weekly GLP-1/glucagon dual agonist (Boehringer Ingelheim/Zealand) studied for obesity and MASH. Not approved; in Phase 3 development.
Mazdutide: A GLP-1/glucagon dual agonist (an oxyntomodulin analog) developed by Innovent, chiefly in China, for weight loss and diabetes. Its approval status is region-specific; investigational in the US.
Amycretin: An investigational Novo Nordisk GLP-1 + amylin co-agonist in both oral and injectable forms. Early-phase data are promising but small and short; not approved.
Pemvidutide: An investigational GLP-1/glucagon dual agonist (Altimmune) designed to favor fat loss over lean-mass loss, studied in obesity and MASH. Not approved.

Peptides

Peptide: A short chain of amino acids — smaller than a protein — that can act as a signaling molecule. Many 'research peptides' lack human trial data and FDA approval.
Amino acid: The building blocks of peptides and proteins. Chains of amino acids fold into the molecules that drive most biology.
BPC-157: A synthetic peptide marketed for tissue repair. Evidence is almost entirely preclinical (animal/in-vitro); there are no robust human trials, and it is not an approved drug.
TB-500 / Thymosin β4: A peptide fragment marketed for healing. The studied molecule (thymosin β4) has limited human data, mainly in eye disease; injectable 'TB-500' for recovery is untested and WADA-prohibited.
GHK-Cu: A copper-binding tripeptide with credible evidence for topical cosmetic skin benefits; systemic/injected use has no human trials.
Sermorelin: A growth-hormone-releasing hormone (GHRH) analog historically used to diagnose/treat childhood growth hormone deficiency; now marketed off-label for anti-aging.
Ipamorelin: A growth hormone secretagogue peptide marketed to raise GH/IGF-1. Rigorous human efficacy data are minimal, and supply is unregulated 'research-use'.
CJC-1295: A long-acting GHRH analog often paired with ipamorelin. Like ipamorelin, it lacks robust human outcome data and is not an approved therapy.
Tesamorelin: A GHRH analog (Egrifta) that is FDA-approved — but specifically to reduce excess abdominal fat in HIV-associated lipodystrophy, not for general anti-aging.
Growth hormone secretagogue: A compound that prompts the body to release its own growth hormone (e.g., ipamorelin), as opposed to injecting GH directly.
GHRH: Growth-hormone-releasing hormone — the natural signal that tells the pituitary to release growth hormone. Sermorelin, CJC-1295, and tesamorelin are GHRH analogs.
Certificate of Analysis (COA): A third-party lab document attesting to a product's identity, purity, and lack of contaminants — a key transparency signal for compounded or research products.
Tesofensine: An investigational triple monoamine reuptake inhibitor (not a peptide) with striking but flagged Phase 2 weight-loss data; never FDA-approved.
MK-677 (Ibutamoren): An oral ghrelin mimetic that reliably raises GH and IGF-1 — but its trials showed no functional benefit, plus metabolic and cardiac safety signals. Never approved.
Semax: A Russian-developed ACTH(4-10)-analog nootropic peptide that raises BDNF; human evidence is small and largely from Russia. Not FDA-approved.
Selank: A Russian tuftsin-analog anxiolytic peptide that modulates GABA without being a benzodiazepine; lightly tested. Not FDA-approved.
5-Amino-1MQ: A small-molecule NNMT inhibitor marketed for fat loss. It reverses obesity in mice but has zero human clinical trials.
PT-141 (Bremelanotide): A melanocortin-receptor agonist that is genuinely FDA-approved (as Vyleesi) for low sexual desire in premenopausal women.
Kisspeptin: A hormone that sits upstream of the reproductive axis, triggering LH/FSH release. Real reproductive-science interest; unproven as a sold therapy.
MOTS-c: A mitochondrial-derived peptide with real metabolic biology in animals but essentially no controlled human evidence for its marketed uses.
IGF-1: Insulin-like growth factor 1 — the hormone, made mainly by the liver in response to growth hormone, that mediates most of GH's effects.
Reconstitution: Mixing a freeze-dried (lyophilized) peptide with bacteriostatic or sterile water to create an injectable solution — a step prone to sterility error.
Lyophilized: Freeze-dried into a stable powder. Most research peptides ship lyophilized and must be reconstituted before use.
Nootropic: A substance claimed to enhance memory, focus or cognition. Peptide examples (semax, selank) have limited, mostly non-Western human evidence.
BDNF: Brain-derived neurotrophic factor — a protein central to learning, memory and neuron survival, and a proposed target of nootropic peptides like semax.
SARM: Selective androgen receptor modulator — a class of (non-peptide) compounds marketed for muscle growth, distinct from peptides and largely unapproved.
Secretagogue: A substance that prompts a gland to secrete a hormone. Growth-hormone secretagogues (ipamorelin, MK-677) make the pituitary release your own GH rather than injecting it.
GHRP: Growth-hormone-releasing peptide — a class of ghrelin-receptor agonists (GHRP-2, GHRP-6, ipamorelin) that stimulate GH release. Most are WADA-prohibited and unapproved.
Ghrelin: The 'hunger hormone' released by the stomach. Its receptor is the target of GH secretagogues like ipamorelin and MK-677.
Bacteriostatic water: Sterile water containing 0.9% benzyl alcohol that inhibits bacterial growth, used to reconstitute lyophilized peptides for multi-dose use.
Saturation dose: The dose above which a GH secretagogue's pituitary response plateaus — the pharmacology behind the ~1 mcg/kg figures circulated for ipamorelin. Not a clinically validated target.
Subcutaneous injection: An injection into the fat layer just under the skin (often the abdomen) — the usual route for GLP-1 drugs and most peptides.
WADA: The World Anti-Doping Agency, which prohibits many peptides and secretagogues (GHRPs, TB-500, MK-677) in competitive sport.
Research chemical: Products labeled 'for research use only, not for human consumption' — a disclaimer that places them outside the prescription and compounding-pharmacy system.
Gray market: The semi-legal channel selling unapproved peptides as 'research' material — outside pharmacy oversight, with no guarantee of identity, dose or purity.
Epitalon: A synthetic tetrapeptide marketed for telomere and longevity benefits, based largely on older Russian research; no robust independent human trials.
Thymosin α1: An immune-modulating peptide (approved in some countries as Zadaxin for specific uses); the systemic 'wellness' use sold online is unproven.
DSIP: Delta sleep-inducing peptide, marketed for sleep and stress. Human evidence is sparse and dated; not an approved therapy.
AOD-9604: A fragment of human growth hormone marketed for fat loss that failed to beat placebo for weight loss in human trials.
Melanotan II: An unlicensed melanocortin agonist used for tanning and erections, linked to nausea, blood-pressure changes and darkening moles. Not approved.
Peptide stack: Combining multiple peptides in one protocol (e.g., CJC-1295 + ipamorelin) — common in marketing, rarely studied as a combination.
Cerebrolysin: An injectable mixture of pig-brain-derived neuropeptides and amino acids used abroad for stroke and dementia. Evidence is weak and mixed; not FDA-approved in the US.
SS-31 (Elamipretide): A mitochondria-targeting tetrapeptide that binds cardiolipin to stabilize the inner membrane. A strong mechanism with mostly disappointing or mixed human trials; investigational.

Longevity

Healthspan: The portion of life spent in good health, free of chronic disease and disability — distinct from lifespan (total years lived).
NAD⁺: Nicotinamide adenine dinucleotide, a coenzyme essential to energy metabolism and DNA repair. Levels are studied in aging; supplements aim to raise it.
NMN: Nicotinamide mononucleotide, an NAD⁺ precursor sold as a supplement. Human data show it can raise NAD⁺ markers; longevity benefits are unproven.
NR (Nicotinamide riboside): Another NAD⁺ precursor supplement. Trials show it safely elevates NAD⁺, but evidence for healthspan or disease outcomes is limited.
Sirtuins: A family of NAD⁺-dependent enzymes involved in cellular stress response and metabolism, often discussed in aging biology.
mTOR: A central nutrient-sensing pathway that governs cell growth. Inhibiting it (e.g., with rapamycin) extends lifespan in animal models.
Rapamycin: An mTOR inhibitor (an approved immunosuppressant) studied off-label for longevity. Human evidence is short-term/biomarker-level, not lifespan outcomes.
Senolytic: A compound intended to clear 'senescent' (worn-out, non-dividing) cells thought to drive aging. Human evidence is early-stage.
Autophagy: The cell's recycling process for clearing damaged components. It is a frequent target of longevity interventions like fasting and rapamycin.
Taurine: An amino acid studied for aging. Animal data are promising, but 2025 human work questioned whether circulating taurine reliably declines with age.
Urolithin A: A gut-microbiome postbiotic (Mitopure) that induces mitophagy; real RCT data improving muscle endurance, though primary strength endpoints often missed.
Spermidine: A polyamine that induces autophagy, with mouse-lifespan data and a human mortality association — but a null result in its best randomized trial.
Fisetin: A flavonoid that is the most potent senolytic of its class in mice, with lifespan data — but no published human senolytic outcome trials yet.
Quercetin: A flavonoid with a modest blood-pressure benefit; its senolytic reputation belongs to the dasatinib+quercetin (D+Q) combo, not quercetin alone.
Resveratrol: A polyphenol that extended lifespan in yeast and mice (via SIRT1) but disappointed in humans — and even blunted exercise gains in one trial.
Berberine: A plant alkaloid that activates AMPK, with real (low-certainty) human data for glucose and lipids. It is not a GLP-1 drug or a weight-loss agent.
AMPK: AMP-activated protein kinase — the cell's energy-sensing switch. Activated by metformin and berberine, and a hub of metabolic-aging research.
Cellular senescence: A state in which cells stop dividing but don't die, secreting inflammatory signals (the SASP) that degrade surrounding tissue with age.
SASP: The senescence-associated secretory phenotype — the cocktail of inflammatory molecules senescent cells release, a target of senolytic compounds.
Caloric restriction: Sustained reduction in calorie intake without malnutrition — the most reproducible lifespan-extending intervention in animals; many supplements claim to mimic it.
Mitophagy: The selective autophagy (clearance) of damaged mitochondria — the cellular housekeeping that urolithin A is designed to induce.
Mitochondria: The cell's energy-producing organelles. Their decline with age is a central theme in longevity science and in NAD⁺/mitophagy interventions.
Telomere: A protective cap on the end of a chromosome that shortens with each cell division. Telomerase rebuilds it — the basis of (mostly unproven) peptide claims like epitalon's.
NNMT: Nicotinamide N-methyltransferase — an enzyme overexpressed in fat and muscle in metabolic disease; inhibiting it (e.g., with 5-Amino-1MQ) spares the NAD⁺ pool.
Testosterone: The primary male sex hormone, governing libido, muscle, bone, mood and sperm production. Levels are diagnosed via morning blood tests.
TRT: Testosterone replacement therapy — supplying testosterone from outside (gel, injection, pellet) to treat diagnosed hypogonadism. It suppresses fertility.
Hypogonadism: Clinically low testosterone with symptoms, confirmed on repeat morning blood tests — the condition TRT is actually indicated for.
Enclomiphene: A SERM (the active isomer of clomiphene) that raises a man's own testosterone via LH/FSH while preserving fertility. Not FDA-approved for men; compounded.
Clomiphene: A selective estrogen receptor modulator approved for female fertility, used off-label in men to raise testosterone. Enclomiphene is its active half.
hCG: Human chorionic gonadotropin — a hormone that stimulates the testes directly, used to maintain testosterone and fertility, sometimes alongside TRT.
LH (Luteinizing hormone): A pituitary hormone that signals the testes to produce testosterone. External testosterone suppresses it; enclomiphene raises it.
FSH: Follicle-stimulating hormone — a pituitary hormone that drives sperm production. Like LH, it's suppressed by TRT and raised by enclomiphene.
HPG axis: The hypothalamic-pituitary-gonadal feedback loop that regulates testosterone and fertility. TRT shuts it down; enclomiphene works through it.
Estradiol: The main estrogen. Testosterone is converted to it by the enzyme aromatase, which is why estradiol is often monitored on hormone therapy.
Aromatase: The enzyme that converts testosterone into estradiol. 'Aromatase inhibitors' (e.g., anastrozole) are sometimes used to manage estrogen on TRT.
SHBG: Sex-hormone-binding globulin — a protein that binds testosterone in the blood, leaving only the unbound (free) fraction biologically active.
Free testosterone: The unbound, biologically active fraction of testosterone not attached to SHBG or albumin — sometimes measured when total levels are ambiguous.
Erythrocytosis: An increase in red blood cells (raised hematocrit) — the most common lab effect of TRT, greatest with injections, which is why hematocrit is monitored.
Hematocrit: The percentage of blood made up of red cells. TRT raises it; if it climbs too high the blood thickens, raising clot risk — a key monitoring lab.
PSA: Prostate-specific antigen — a blood marker monitored before and during TRT as part of prostate-cancer screening.
SERM: Selective estrogen receptor modulator — a drug that blocks or mimics estrogen depending on tissue. Enclomiphene and clomiphene are SERMs used to raise testosterone.
Glutathione: The body's 'master antioxidant,' a tripeptide. Oral supplementation can raise body stores; IV 'gluta drips' are popular for skin but lack outcome evidence.
NAC (N-acetylcysteine): A cysteine precursor that helps the body make glutathione. It's an approved drug for acetaminophen overdose and is widely sold as a supplement.
GlyNAC: Glycine plus N-acetylcysteine taken together to rebuild glutathione. Small trials report broad benefits in older adults, not yet independently replicated.
Methylene blue: A century-old synthetic dye and approved drug (for methemoglobinemia), now marketed at low doses for 'mitochondrial' and cognitive benefits. A real drug with a serotonin-syndrome risk, not a benign supplement.
Sulforaphane: A broccoli-sprout compound that activates the Nrf2 antioxidant pathway. Real RCTs in specific conditions, but not a proven anti-aging agent.
Nrf2: A master regulator of the cell's antioxidant defenses, activated by sulforaphane — a frequent target of longevity supplements.
Calcium AKG (Ca-AKG): Calcium alpha-ketoglutarate, a TCA-cycle metabolite marketed for aging. Mouse data show compressed morbidity; human 'biological age' claims come from uncontrolled studies.
Sirolimus: The generic name for rapamycin — an FDA-approved mTOR inhibitor used in transplant medicine and studied off-label for longevity.
Epigenetic clock: An algorithm that estimates 'biological age' from DNA-methylation patterns — a popular but still-maturing aging biomarker.
Biological age: An estimate of how old your body seems physiologically — from biomarkers or epigenetic clocks — versus chronological age in years.
Hallmarks of aging: A widely-cited framework of the cellular processes that drive aging (genomic instability, senescence, mitochondrial dysfunction and more) that longevity interventions aim to target.
Inflammaging: The chronic, low-grade inflammation that rises with age and is linked to many age-related diseases.
Mitochondrial dysfunction: The age-related decline of the cell's energy factories — a core hallmark of aging targeted by NAD⁺, urolithin A and related interventions.
Polyamine: A class of small molecules (e.g., spermidine) involved in cell growth and autophagy, studied in longevity research.
Cardiolipin: A signature lipid of the inner mitochondrial membrane whose integrity is central to energy production — the binding target of the peptide SS-31/elamipretide.
SLU-PP-332: A synthetic 'exercise-mimetic' compound that activates estrogen-related receptors. Evidence is entirely preclinical (mice/in-vitro); there are no human studies.
Exercise mimetic: A hypothetical drug meant to reproduce the metabolic benefits of exercise (endurance, fat loss) without the workout. None is proven in humans.
Estrogen-related receptor (ERR): A family of nuclear receptors (ERRα/β/γ) that regulate oxidative metabolism and mitochondrial biogenesis — the target of exercise-mimetic compounds like SLU-PP-332.
Mitochondrial biogenesis: The creation of new mitochondria — the adaptation endurance exercise drives, and the effect exercise-mimetic compounds try to trigger pharmacologically.

General

Compounded medication: A drug mixed by a pharmacy for an individual patient. Compounded GLP-1s are not FDA-approved or pre-market-reviewed for safety and efficacy the way branded drugs are.
503A / 503B pharmacy: Sections of U.S. law defining compounding pharmacies: 503A serve individual prescriptions; 503B 'outsourcing facilities' make larger batches under stricter oversight.
Titration: Gradually increasing a medication's dose over weeks to build tolerance and limit side effects — standard for GLP-1 drugs.
Half-life: The time it takes for half a drug to clear the body. Longer half-lives allow less-frequent dosing (e.g., once-weekly semaglutide).
Bioavailability: The fraction of a dose that reaches the bloodstream intact. Oral peptides have low bioavailability, which is why most are injected.
LegitScript: A third-party certification service that vets telehealth and pharmacy operators for legal compliance — a trust signal when evaluating providers.
Off-label: Prescribing an FDA-approved drug for a use, dose, or population it wasn't approved for — legal and common, but the evidence for that use may be weaker.
Randomized controlled trial (RCT): The gold-standard study design: participants are randomly assigned to a treatment or a control (often placebo), minimizing bias.
Placebo: An inert comparator (e.g., a dummy injection) used in trials so a drug's real effect can be separated from expectation and natural change.
Meta-analysis: A study that statistically pools results from multiple trials to produce a combined estimate — stronger than any single trial, but only as good as its inputs.
Primary endpoint: The main, pre-specified outcome a trial is designed and powered to measure. A drug that hits secondary endpoints but misses the primary hasn't really 'won.'
Surrogate endpoint: A marker (e.g., a lab value like IGF-1) used as a stand-in for a real outcome. Moving a surrogate is not the same as improving health.
Non-inferiority: A trial designed to show a treatment is 'not meaningfully worse' than a comparator — the standard met by TRT for cardiac safety in the TRAVERSE trial.
FDA approval: The U.S. regulatory bar requiring pivotal human trials proving a drug is safe and effective for a defined use — which most 'research' peptides have never cleared.
PubMed / PMID: PubMed is the NIH's database of biomedical literature; a PMID is a paper's unique ID. Every claim on this site is tied to a verifiable PMID.
Compounded semaglutide: Semaglutide prepared by a compounding pharmacy rather than the manufacturer. It is not FDA-approved, and the legal pathway has narrowed since the shortage ended.
WAC (wholesale acquisition cost): A drug's manufacturer list price to wholesalers before rebates — the 'sticker' figure cited for brand drugs, usually higher than what anyone actually pays.
Cash-pay (self-pay): Paying out of pocket without billing insurance — the model for most compounded GLP-1 and peptide telehealth, where prices are quoted upfront.
Telehealth: Medical care delivered remotely by video, phone or online intake — the dominant channel for compounded GLP-1, TRT and peptide prescriptions.
Prior authorization: An insurer's requirement that a prescriber justify a drug before it's covered — a common hurdle for branded GLP-1 weight-loss medications.
Step therapy: An insurance rule requiring you to try (and fail) a cheaper drug before a costlier one is covered.
Formulary: The list of drugs an insurance plan covers, and at what tier — which determines your out-of-pocket cost.
Generic drug: A copy of an off-patent brand drug with the same active ingredient, proven bioequivalent and sold far cheaper (e.g., sirolimus for Rapamune).
Biosimilar: A near-copy of an off-patent biologic drug — highly similar but, unlike a small-molecule generic, not identical.
Route of administration: How a drug enters the body — oral, subcutaneous, intramuscular or intravenous — which affects dosing, absorption and cost.
Intravenous (IV): Delivery directly into a vein, used for NAD⁺ and glutathione 'drips' — fast, complete absorption, but the priciest and least-evidenced route for these.
Intramuscular (IM): Injection into a muscle — a common route for testosterone and some vitamin or NAD⁺ injections.
Bioequivalence: The standard a generic must meet: it delivers the same amount of active drug to the bloodstream as the brand it copies.
Contraindication: A condition that makes a treatment inadvisable or unsafe — e.g., a personal or family history of medullary thyroid cancer for GLP-1 drugs.
Investigational drug: A drug still in clinical testing that no regulator has approved. It cannot be legally prescribed or sold for treatment, only used within an authorized clinical trial.
Clinical trial phases: Human testing runs in stages: Phase 1 (safety, small), Phase 2 (early efficacy/dose), Phase 3 (large, pivotal). Approval normally requires successful Phase 3 trials.
ClinicalTrials.gov: The U.S. public registry of clinical studies — the legitimate place to find and enroll in trials of investigational drugs like retatrutide or survodutide.
Boxed warning: The FDA's most serious label warning, set off in a black border. GLP-1 drugs carry one for a rodent thyroid C-cell tumor signal (contraindicated in MEN 2 and medullary thyroid cancer).
Endotoxin: A bacterial contaminant that can cause fever and dangerous reactions if injected — a core safety reason not to inject non-pharmaceutical 'research' peptides.
Orphan drug: A drug developed for a rare disease, which earns FDA incentives — the pathway behind therapies like elamipretide for rare mitochondrial conditions.