Glossary

Plain-language definitions of the terms used throughout AnabolicDex. Bookmark this page or follow inline links to come back here.

Half-life (t½): The time it takes for the concentration of a compound in the blood to drop by half. A drug with a 7-day half-life loses 50% of its peak level every 7 days. Half-life determines dosing frequency, steady-state timing, and clearance.
Cmax: The maximum (peak) concentration a compound reaches in the blood after a dose. Higher Cmax means stronger effect — and often more side effects at that moment.
Tmax: The time after a dose at which Cmax (peak concentration) is reached. A short Tmax means the compound hits hard and fast; a long Tmax means a slow, gradual rise.
Bioavailability (F): The fraction of the administered dose that actually reaches systemic circulation. Injectable compounds are typically ~100% (minus losses); oral compounds are often much lower (e.g. oral semaglutide is ~1%) due to digestion and first-pass metabolism.
Steady state: The point at which the amount of drug absorbed per dose equals the amount eliminated — levels stop climbing and oscillate within a stable range. Typically reached after 4–5 half-lives.
Trough: The lowest concentration reached just before the next dose. Trough levels are the standard for bloodwork timing — they reflect the steady-state floor, not the peak.
Accumulation: When doses are given before the previous dose fully clears, levels build up over time. Long-half-life compounds accumulate significantly — troughs climb for weeks before stabilizing at steady state.
Ester: A chemical group attached to a hormone (e.g. testosterone) that controls its release rate. The ester is slowly cleaved by enzymes in the body, releasing the active hormone. Longer esters = slower release = longer half-life (e.g. cypionate vs. propionate).
Aromatization: The conversion of testosterone to estradiol (estrogen) by the aromatase enzyme. The amount of aromatization tracks total testosterone exposure — higher peaks and larger doses produce more E2 conversion.
SERM: Selective Estrogen Receptor Modulator. A drug that blocks estrogen at specific tissues (e.g. breast) without lowering systemic estrogen. Used in PCT and for gynecomastia treatment (e.g. tamoxifen, clomiphene).
AI (Aromatase Inhibitor): A drug that reduces estrogen production by blocking the aromatase enzyme (e.g. anastrozole, exemestane). Used on-cycle when estradiol climbs too high. Narrow therapeutic window — easy to overshoot and crash E2.
PCT (Post-Cycle Therapy): A protocol used after a cycle of exogenous hormones to restore natural testosterone production. Typically involves SERMs (tamoxifen/clomiphene) to stimulate the HPTA.
HPTA: Hypothalamic-Pituitary-Testicular Axis. The feedback loop that regulates natural testosterone production. Exogenous hormones suppress it; PCT aims to restart it.
GLP-1: Glucagon-Like Peptide-1. An incretin hormone that stimulates insulin, suppresses glucagon, slows gastric emptying, and reduces appetite. GLP-1 agonists (semaglutide, tirzepatide) are used for diabetes and weight loss.
Reconstitution: The process of dissolving lyophilized (freeze-dried) peptide powder in bacteriostatic water to create an injectable solution. The concentration (mg/mL) depends on the vial size and water volume.
Subcutaneous (SQ) injection: Injection into the fatty tissue just under the skin (e.g. abdomen, thigh). Used for peptides, insulin, and GLP-1 agonists. Smaller needle gauge than intramuscular.
Intramuscular (IM) injection: Injection deep into muscle tissue (e.g. glute, quad, deltoid). Used for oil-based hormones (testosterone esters, nandrolone). Requires a larger-gauge needle than subcutaneous.
SARM (Selective Androgen Receptor Modulator): A non-steroidal compound that activates the androgen receptor in muscle and bone tissue while aiming to spare the prostate and other androgenic tissues. Investigational and not FDA-approved. Examples include ostarine (MK-2866) and ligandrol (LGD-4033).
Secretagogue: A compound that stimulates the body to release a hormone. Growth hormone secretagogues (like ipamorelin, MK-677) prompt the pituitary to release GH rather than introducing it directly.
GHRP (Growth Hormone Releasing Peptide): A class of peptides that stimulate GH release through the ghrelin (GHS-R1a) receptor. Examples: GHRP-6, GHRP-2, ipamorelin. They work through a different pathway than GHRH analogs, so stacking the two produces synergy.
GHRH (Growth Hormone Releasing Hormone): A hypothalamic peptide that stimulates the pituitary to release growth hormone in pulses. Synthetic analogs include sermorelin, CJC-1295, and tesamorelin.
Lyophilized: Freeze-dried. Peptides are shipped as lyophilized powder that must be reconstituted with bacteriostatic water before injection. Lyophilization removes moisture, giving peptides shelf life of 1-2 years refrigerated.
AUC (Area Under the Curve): The total drug exposure over time, calculated by integrating the concentration curve. AUC captures both how high the peaks are and how long they last. It is a better measure of total exposure than peak concentration alone.
First-pass metabolism: The liver processes orally administered compounds before they reach systemic circulation. This destroys a large fraction of many drugs, which is why oral bioavailability is often low. Injectable and sublingual routes bypass first-pass.
Depot: The injection site acts as a reservoir (depot) that slowly releases the compound into the bloodstream. Oil-based esters and microcrystal suspensions create depots that extend release over days or weeks.
DPP-4: Dipeptidyl peptidase-4, the enzyme that rapidly degrades native GLP-1 (within 1-2 minutes). DPP-4 inhibitors (sitagliptin) extend the life of endogenous GLP-1. GLP-1 agonists like semaglutide are structurally modified to resist DPP-4.
WADA: The World Anti-Doping Agency. Sets the prohibited list and accredits anti-doping labs. WADA maintains technical documents (TD series) specifying detection methods and thresholds for each class of prohibited substance.
Metabolite: A breakdown product of a parent compound. Anti-doping labs often target specific long-lived metabolites rather than the parent drug, because metabolites persist in urine far longer. The metabolite choice determines the detection window.
Detection window: The period after the last dose during which a compound or its metabolites are detectable in a drug test. Determined by dose, duration, metabolism, and the specific assay. Long-lived metabolites extend the window well beyond the parent compound half-life.
GC-MS: Gas chromatography-mass spectrometry. A laboratory technique used to identify and quantify compounds in biological samples. The gold-standard confirmation method in anti-doping testing.
IRMS (Isotope Ratio Mass Spectrometry): A technique that measures the carbon isotope ratio (13C/12C) of steroids to distinguish endogenous (naturally produced) from exogenous (administered) testosterone. Used as confirmation when the T/E ratio is elevated.
T/E ratio: The ratio of testosterone to epitestosterone in urine. The standard screening marker for testosterone doping. A ratio above 4:1 triggers confirmatory testing by IRMS. Note: some individuals naturally have elevated ratios.
HPGA: Hypothalamic-Pituitary-Gonadal Axis. The three-organ system that regulates reproductive hormone production. Exogenous hormones suppress it at multiple levels; recovery after suppression requires time and often pharmacological help (PCT).
HPTA: Hypothalamic-Pituitary-Testicular Axis. The specific portion of the HPGA relevant to male testosterone production. GnRH from the hypothalamus signals LH from the pituitary, which signals testosterone from the testes.
Negative feedback: The mechanism by which high levels of a hormone signal the body to produce less. Exogenous testosterone suppresses GnRH and LH through negative feedback, which is why the body stops producing its own testosterone during a cycle.
DHT (Dihydrotestosterone): A potent androgen converted from testosterone by the 5-alpha-reductase enzyme. DHT drives androgenic side effects like hair loss, prostate growth, and acne. Some compounds (DHT derivatives) are already in this form and cannot be further reduced.
5-alpha reductase: The enzyme that converts testosterone to DHT. Inhibitors like finasteride block this conversion. Compounds that are already DHT derivatives (like primobolan, masteron) are unaffected by 5-alpha reductase.
SHBG (Sex Hormone Binding Globulin): A protein that binds testosterone in the blood, rendering it inactive. Only free (unbound) testosterone is biologically active. High SHBG reduces free T even when total T is normal. Some compounds (like winstrol) lower SHBG.
Vermeulen formula: The standard equation for calculating free testosterone from total testosterone, SHBG, and albumin. Named after Dr. Alex Vermeulen. More accurate than direct analog-based lab tests for free T.
Insulin syringe: A small syringe calibrated in units where 100 units equals 1 mL. Standard for peptide injections (subcutaneous). Higher gauge (thinner needle) than intramuscular syringes, typically 29-31 gauge.
Lipolysis: The breakdown of fat (triglycerides) into free fatty acids for energy use. Compounds that promote lipolysis (like HGH fragment, clenbuterol, GLP-1 agonists) are studied for fat-loss applications.

Educational use only — not medical advice. Definitions are simplified for accessibility; consult clinical literature for precise pharmacological detail.