Glossary

The key terms — explained briefly and clearly.

5

503B / Outsourcing Facility: A US-registered manufacturing pharmacy that may also produce medicines in larger quantities without an individual prescription — with higher quality requirements than the classic 503A pharmacy. For several GLP-1 drugs the compounding permissions expired in 2025.

Accelerated Approval: An expedited US approval pathway by the FDA based on promising but not yet definitive endpoints. The approval can be tied to confirming the benefit in further studies.
Agonist: A substance that activates a receptor and thereby triggers a biological response — as opposed to an antagonist, which blocks the receptor.
Angiogenesis: The formation of new blood vessels. In peptide research often mentioned in connection with healing and repair processes.

Bioavailability: The fraction of an active substance that reaches the bloodstream unchanged and can take effect. Depends strongly on the route of uptake.

Compounding (503A): The individual preparation of medicines by pharmacies. In the US the FDA reviews which bulk substances are permissible for this; some peptides were assessed with safety concerns.
Contraindication: A circumstance (e.g. illness, pregnancy) in which an active substance should not be used because the risk outweighs the benefit.

Falsified medicine: A counterfeit product that imitates a real medicine but may contain the wrong, missing or contaminated active ingredient. Documented repeatedly for GLP-1 products by EMA, WHO and BfArM — in part with dangerous active-ingredient mix-ups.

GIP: Glucose-dependent insulinotropic polypeptide — an incretin hormone of the gut. A target receptor of modern metabolic drugs (e.g. tirzepatide).
GLP-1: Glucagon-like peptide-1 — a gut hormone that promotes insulin secretion in a glucose-dependent way, curbs appetite and slows gastric emptying.
Glucagon: A hormone that raises blood sugar and influences energy expenditure. Triple agonists also target the glucagon receptor.

Half-life: The time in which the concentration of a substance in the body falls by half. A pharmacological parameter — here purely informative, not a dosing aid.

Ileus: Intestinal paralysis or obstruction in which the passage through the gut comes to a standstill — a medical emergency. As a rare, serious signal of slowed gastrointestinal motility it was added to the US product information for semaglutide.
In vitro / In vivo: “In vitro” = in the test tube/cell culture, “in vivo” = in the living organism. Preclinical findings often come from cell or animal experiments.
Incretin: Collective term for gut hormones (e.g. GLP-1, GIP) that promote insulin secretion after eating. Incretin mimetics imitate this effect.
Investigational: An investigational substance that is in clinical trials and does not (yet) have market approval.

MASH / NASH: Metabolic (formerly: non-alcoholic) steatohepatitis — a fatty liver disease with inflammation, considered a research field for several metabolic drugs.

NAION: Non-arteritic anterior ischemic optic neuropathy — a rare circulatory disorder of the optic nerve that appears as sudden, often painless vision loss in one eye and can be permanent. Classified in 2025 by the EMA safety committee as a very rare side effect of semaglutide.

Off-label: The use of an approved medicine outside the authorised indication — a medical decision carrying its own responsibility and counselling.

Peptide: A short chain of amino acids. Peptides act in the body as hormones and signaling molecules, among other things; many are broken down enzymatically very quickly.
Pharmacokinetics: What the body does with an active substance: uptake, distribution, metabolism and excretion.
Preclinical: Research before clinical trials in humans — typically cell and animal experiments. Promising preclinical data are no proof of benefit in humans.

Reconstitution: Dissolving a powdered active substance in a liquid. Deliberately not included as a guide in this app — it is a knowledge resource, not a usage resource.

Subcutaneous: “Under the skin” — a route of administration into the subcutaneous fat tissue. Explained here only as a pharmacological term, not as a guide.

WADA: World Anti-Doping Agency. Maintains the prohibited list, which includes several research peptides (e.g. BPC-157, TB-500).