Address
304 North Cardinal
St. Dorchester Center, MA 02124
Work Hours
Monday to Friday: 7AM - 7PM
Weekend: 10AM - 5PM
The Peptide Glossary
For research and educational purposes only. All compounds discussed on AethonLabs.ca are sold strictly for research use and are not intended for human consumption. Always consult a qualified healthcare professional before beginning any new protocol.
Last updated: July 2026
Every guide on this site uses terms that assume you already know what they mean, and that’s not a great assumption to make about anyone reading this for the first time. This page exists to fix that. It’s not meant to be read start to finish — keep it open in another tab and search it while you’re reading anything else on this site. Terms are listed alphabetically.
A
Agonist — A compound that binds to a receptor and activates it, triggering the same kind of response the body’s own natural signal would. Nearly every compound discussed on this site is a receptor agonist of some kind — the differences between them come down to which receptor, and how selectively.
AMPK (AMP-activated protein kinase) — A cellular energy sensor that, when activated, improves glucose uptake, promotes fat oxidation, and supports mitochondrial function. This is MOTS-C’s primary mechanism.
Analog — A synthetic compound engineered to resemble a naturally occurring molecule closely enough to activate the same receptors, usually with a specific modification meant to improve stability, potency, or duration of action compared to the original. Most compounds on this site are analogs of something the body already produces.
B
Bacteriostatic water (BAC water) — Sterile water containing 0.9% benzyl alcohol, used to reconstitute most lyophilized peptides. The benzyl alcohol inhibits bacterial growth, which is what allows a reconstituted vial to be safely punctured and drawn from repeatedly over its usable window, rather than needing to be used all at once.
BDNF (brain-derived neurotrophic factor) — A protein that supports the growth, survival, and connectivity of neurons, with a central role in learning and memory. This is Semax’s primary documented mechanism.
Benzyl alcohol — The preservative agent in bacteriostatic water, responsible for inhibiting bacterial growth in a reconstituted, multi-dose vial.
Bioavailability — The proportion of a compound that actually reaches circulation and becomes available to act on its target, after accounting for how it was administered. Subcutaneous injection generally produces high bioavailability; oral administration of most peptides produces very low bioavailability, since digestion breaks them down before absorption — which is part of why a small number of compounds (BPC-157 and KPV among them) are specifically notable for having documented oral activity at all.
C
Certificate of Analysis (COA) — A laboratory document reporting the testing performed on a specific production batch of a compound, typically covering purity (via HPLC) and identity confirmation (via mass spectrometry). See our full guide on reading a COA for the complete picture.
Compounding pharmacy — A pharmacy licensed to prepare custom medication formulations, typically under a practitioner’s prescription, using bulk active ingredients rather than pre-manufactured commercial products. Some research peptides have, at various points, been available through this route; several were restricted from it by FDA action starting in 2023.
Concentration — How much compound is present per unit of liquid volume, expressed in mg/mL. This is the number that results from reconstitution and that every dose calculation depends on. Our dose math guide covers this in full.
Contraindication — A specific condition or situation in which a compound should not be used, because the risk of harm is considered to outweigh any potential benefit.
D
DAC (Drug Affinity Complex) — A chemical modification that binds a compound to albumin, a protein that circulates abundantly in blood, extending the compound’s functional half-life significantly. CJC-1295 exists in both a with-DAC (long-acting, once-weekly) and without-DAC (short-acting, once-daily) version, and the two are not interchangeable.
Discontinuation — What happens, physiologically, when a compound is stopped after a period of use. For compounds addressing an ongoing condition rather than a temporary state, effects often fade back toward baseline once use stops, rather than persisting indefinitely.
Dose-dependent — An effect (therapeutic or adverse) whose intensity changes with the amount of compound administered — generally, though not always proportionally, increasing with a higher dose.
E
Endotoxin — A toxic substance associated with certain bacteria, capable of causing fever, inflammation, or more serious reactions if present in an injected solution. Endotoxin testing is one of the expanded testing options some labs offer beyond basic purity and identity confirmation.
Evidence tier — A way of categorizing how much confidence a specific claim actually deserves: a completed human trial testing the exact outcome in question sits at the top, followed by human trials testing something else, animal/preclinical research, and community-reported experience at the base. Understanding which tier a piece of evidence belongs to is the single most useful research skill covered anywhere on this site.
F
Fasted state — Having not eaten for a meaningful period (typically two to three hours, for the compounds where this matters) before administration. Relevant specifically for GH-axis compounds like CJC-1295 and Ipamorelin, since elevated insulin from recent food intake suppresses the pituitary’s GH response.
G
GHRH (Growth Hormone-Releasing Hormone) — A hormone that stimulates the pituitary gland to release growth hormone. CJC-1295 and Tesamorelin are both GHRH receptor analogs.
GHRP (Growth Hormone-Releasing Peptide) — An older class of compounds that stimulate GH release through the ghrelin receptor, generally with more off-target effects (elevated cortisol, prolactin, or appetite stimulation) than newer, more selective compounds in the same functional category.
GHS-R (Growth Hormone Secretagogue Receptor) — Also called the ghrelin receptor. Ipamorelin activates this receptor specifically, which is a separate pathway from the GHRH receptor CJC-1295 and Tesamorelin use — the basis for why the two are so often combined.
GLP-1 (Glucagon-Like Peptide-1) — A naturally occurring gut hormone involved in appetite regulation, gastric emptying, and glucose-dependent insulin release. Semaglutide, tirzepatide, and retatrutide all activate the GLP-1 receptor as at least part of their mechanism.
H
Half-life — The time it takes for half of an administered dose to be cleared from the body. A short half-life (minutes to an hour) means a compound needs frequent dosing to maintain its effect; a long half-life (many hours to days) supports less frequent administration.
HPLC (High-Performance Liquid Chromatography) — A laboratory technique that separates and measures the components of a sample, used to determine purity — what proportion of a vial’s contents is actually the target compound versus impurities or degradation products.
I
IGFBP (Insulin-like Growth Factor Binding Protein) — A family of proteins that bind circulating IGF-1, limiting how much is available to activate receptors at any given time. IGF-1 LR3 is specifically engineered to evade this binding, which is why it has a much longer half-life than native IGF-1.
Intramuscular (IM) — Injection directly into muscle tissue, rather than the fat layer just beneath the skin. Less common than subcutaneous injection across the compounds on this site, though used by some researchers for targeted, local effects with specific compounds like BPC-157.
L
Lipohypertrophy — A localized thickening of fat tissue caused by repeatedly injecting the same small area. Beyond being a cosmetic issue, it can reduce and destabilize how consistently a compound is absorbed at that site — the primary reason injection site rotation matters.
Lyophilized — Freeze-dried. This is the powder form nearly every peptide on this site arrives in, chosen because it’s significantly more stable and longer-lasting than a pre-dissolved liquid solution.
M
Mass spectrometry — A laboratory technique that identifies a compound by its molecular weight and fragmentation pattern, used to confirm identity — that a vial actually contains the specific molecule its label claims, not just something pure.
Melanocortin receptor — A family of receptors (MC1R through MC5R) involved in pigmentation, appetite, energy balance, and sexual function, among other roles. Melanotan II activates several of these non-selectively; more targeted drugs like bremelanotide were developed to isolate just one.
N
NDA (New Drug Application) — The formal submission a pharmaceutical company files with the FDA to seek approval for a new drug, following completed clinical trials. A compound that hasn’t had an NDA filed and approved is not an approved drug, regardless of how much research or public discussion exists around it.
Non-selective — Describing a compound that activates multiple receptor subtypes at similar strength, rather than targeting just one. This is the source of Melanotan II’s multiple simultaneous effects (pigmentation, appetite change, libido effects) from a single dose.
O
Off-label — Using an approved drug for a purpose other than the specific indication it was approved for. Legal for a physician to prescribe, but meaningfully different from a use case that’s actually been studied and approved.
P
Peptide — A short chain of amino acids, typically between 2 and 50, distinguished from a protein mainly by length. See “What Is a Peptide, Actually?” in our beginner’s guide for the full explanation.
Pharmacokinetics — How a compound moves through the body over time: absorption, distribution, metabolism, and elimination. Half-life is one specific pharmacokinetic property among several.
Phase 1 / Phase 2 / Phase 3 trial — The sequential stages of human clinical testing a drug candidate goes through on the way to approval. Phase 1 establishes basic safety and dosing in a small group; Phase 2 tests for efficacy signals in a larger group; Phase 3 confirms efficacy and safety in a large, often multi-site trial, and is generally what supports an actual approval decision.
Pituitary gland — A small gland at the base of the brain responsible for releasing growth hormone and several other hormones, in response to signals from the hypothalamus. Most GH-axis compounds discussed on this site work by influencing pituitary activity.
Preclinical — Research conducted before human trials, typically in animal models or cell cultures. Preclinical evidence can establish that a mechanism is real and biologically plausible, but doesn’t by itself demonstrate that an effect holds up in humans.
R
Receptor — A protein, usually on the surface of a cell, that a specific molecule binds to in order to trigger a response inside that cell. Nearly every mechanism discussed on this site comes down to a compound binding a specific receptor.
Reconstitution — The process of dissolving lyophilized peptide powder into a liquid (usually bacteriostatic water) to create an injectable solution. Our full reconstitution guide covers this step by step.
Research-grade — Describing a compound or supply (like BAC water) manufactured for research use rather than to pharmaceutical (medical-grade) standards. Not inherently unsafe, but typically produced with less rigorous, less independently verified manufacturing oversight than an approved pharmaceutical product.
Retrospective study — A study that looks backward at data already collected (often from existing medical records or prior use) rather than following participants forward under controlled conditions. Generally considered weaker evidence than a prospective randomized controlled trial, though still more informative than pure anecdote.
S
Sarcopenic obesity — Carrying both excess body fat and below-optimal muscle mass simultaneously. A relevant consideration for many people starting a GLP-1 protocol, since it raises the stakes on preserving lean mass during weight loss specifically.
Sharps container — A rigid, puncture-resistant container designed for safe disposal of used needles and syringes. Most Canadian community pharmacies provide these free of charge and accept full containers for disposal.
Somatotroph — The specific cell type in the pituitary gland responsible for producing and releasing growth hormone. Both GHRH-receptor and GHS-receptor pathways ultimately act on these same cells.
Stability window — The period during which a reconstituted compound remains reliably potent and safe to use, commonly around 28 days under refrigeration for most peptides on this site, though this can vary by compound.
Subcutaneous (SubQ) — Injection into the layer of fat just beneath the skin, rather than into muscle. The standard route for the large majority of compounds discussed on this site.
Synergistic — Describing an effect produced by two compounds together that’s genuinely greater than the sum of their individual effects, rather than simply additive. CJC-1295 and Ipamorelin’s combined GH pulse is a commonly cited example of a mechanistically plausible synergy — worth remembering that this describes the proposed mechanism, not necessarily a result confirmed by a human trial testing the combination directly.
Systematic review — A structured, methodologically rigorous survey of all available research on a specific question, as opposed to citing a handful of studies selectively. When a systematic review reports finding no eligible trials for a specific claim, that’s a meaningful, precise finding — not just an absence of searching.
T
Titration — Gradually increasing a dose over time, typically to allow the body to adapt and to minimize side effects, rather than starting at a target maintenance dose immediately. Mandatory for most GLP-1 compounds specifically, and good general practice across most of the compounds on this site.
Tyrosinase — The enzyme responsible for converting tyrosine into melanin, the pigment responsible for skin tanning. This is the specific enzyme Melanotan II’s tanning effect works through.
U
Unit (syringe) — A syringe-specific volume measurement, not a universal one. On a standard U-100 insulin syringe, 100 units equals 1 millilitre, meaning each unit equals 0.01mL. Our dose math guide explains this in full, including how to convert between units, millilitres, and milligrams for any compound.
USP (United States Pharmacopeia) — An organization that sets quality and manufacturing standards for pharmaceuticals in the United States. USP standards are frequently referenced as a benchmark for BAC water and other supply quality, even outside the US specifically.
V
Vasodilation — The widening of blood vessels, which can produce sensations of warmth or flushing. This is the mechanism behind the flush some researchers report with NAD+ and certain GH-axis compounds.
Vial — The sealed glass container a peptide is supplied in, typically holding around 3mL of usable volume once reconstituted for most compounds on this site, with some notable exceptions (NAD+ commonly ships in larger 10mL vials, for instance, given its much larger effective doses).
W
WADA (World Anti-Doping Agency) — The organization that maintains the Prohibited List governing substances banned for competitive athletes. WADA status is a separate question entirely from a compound’s domestic legal status — some compounds discussed on this site are prohibited for tested athletes at all times, independent of whether they’re legal to possess.
Where to Go From Here
- Our Complete Beginner’s Guide to Peptides — if you landed here first, that’s the better starting point
- Our Certificate of Analysis and Vendor Verification Guide
- Our Reconstitution Guide
- Our Dose Math Guide
- Our Canadian Regulatory Landscape Guide
This glossary reflects terminology used across this site as of publication and will be updated as new terms come into use. It is provided for research and educational purposes only and does not constitute medical advice. AethonLabs.ca sells all compounds strictly for research use; products are not intended for human consumption. Consult a qualified healthcare professional before beginning any new protocol.
AETHON LABS — Tested. Documented. Delivered.