Glossary & FAQ
Plain-English definitions of the terms used across the Health Guide, and answers to the questions we hear most.
A
Accelerated approval
An FDA pathway that approves a drug based on a surrogate endpoint, with a confirmatory trial usually required.
Agonist
A substance that activates a receptor. A GLP-1 receptor agonist activates the GLP-1 receptor.
Amino acid
The building block of peptides and proteins. There are 20 standard amino acids, and a peptide is defined by its exact sequence.
Amylin
A pancreatic hormone that signals fullness. Cagrilintide and eloralintide are amylin analogues.
Analogue
A modified version of a natural molecule, designed to change properties like stability or how long it lasts.
B
Bioavailability
The share of a substance that reaches the bloodstream. Most peptides are broken down in the gut, so oral bioavailability is usually low.
Bioregulator
A term from Russian research for short peptides proposed to influence specific tissues. It describes a research concept, not proven benefit.
C
Certificate of Analysis (COA)
A lab report on a specific batch, typically covering identity and purity, and sometimes endotoxin or sterility. It does not prove safety or effectiveness.
Compounded drug
A medication prepared by a pharmacy for an individual patient. Compounded drugs are not FDA approved.
D
Dipeptide / tripeptide / tetrapeptide
Peptides made of two, three or four amino acids.
E
Endotoxin
Toxic material from bacterial cell walls. Endotoxin contamination has caused serious reactions with injectable products.
Ex vivo
Studied in living tissue removed from the body and kept alive in the lab.
F
FDA approved
A finished drug product reviewed by the FDA for safety, effectiveness and quality for a specific use.
G
GHRH
Growth-hormone-releasing hormone, made by the hypothalamus. Sermorelin, tesamorelin and CJC-1295 are GHRH analogues.
GHRP / ghrelin receptor
Growth hormone-releasing peptides act on the ghrelin (hunger hormone) receptor. Examples include GHRP-2, GHRP-6 and ipamorelin.
GIP
Glucose-dependent insulinotropic polypeptide, another gut hormone targeted by tirzepatide and retatrutide.
GLP-1
Glucagon-like peptide-1, a gut hormone involved in blood sugar, appetite and stomach emptying.
H
Half-life
The time it takes for half of a substance to be cleared from the body. It does not always match how long an effect lasts.
HPLC
High-performance liquid chromatography, a method for measuring purity. "98% by HPLC" means 98% of the tested sample was the target peptide.
I
IGF-1
Insulin-like growth factor 1, produced mainly by the liver in response to growth hormone. A common lab marker of growth hormone activity.
In vitro
Studied in cells or tissue in a lab dish.
In vivo
Studied in a living organism, such as a mouse or a person.
International Unit (IU)
A measure of biological activity, used for hormones like HGH and hCG. Not the same as volume markings on a syringe.
L
Lot / batch
A specific production run. COAs apply only to the lot tested.
Lyophilization
Freeze-drying. Removing water to make a stable powder for storage.
M
Mass spectrometry (MS)
A method that confirms a peptide's identity by measuring its molecular mass.
O
Open-label
A study where participants and researchers know who receives which treatment.
Orphan designation
A status for drugs targeting rare diseases. It is not approval.
P
Peptide
A short chain of amino acids joined by peptide bonds, generally 2 to about 50. Longer chains are usually called proteins.
Phase 1 / 2 / 3 trial
Phases of human testing: phase 1 checks safety in small groups, phase 2 explores effectiveness and dose, phase 3 confirms benefit and safety in large groups.
Placebo
An inactive comparison treatment used to separate a real effect from expectation or natural change.
Preclinical
Research done before human testing, in cells or animals.
R
Randomized controlled trial (RCT)
A study that randomly assigns people to a treatment or a comparison group, the strongest standard for showing cause and effect.
Research Use Only (RUO)
Products intended only for laboratory research, not for human or veterinary use.
S
Secretagogue
A substance that prompts the body to release another substance. Growth hormone secretagogues prompt the pituitary to release growth hormone.
Surrogate endpoint
A lab or scan measurement used as a stand-in for an outcome people care about, such as fewer fractures or longer survival.
W
WADA Prohibited List
The World Anti-Doping Agency's list of substances banned in sport. Many peptides are on it.
Frequently asked questions
What is a peptide?
A short chain of amino acids. Your body makes many peptides that act as hormones and signals, such as insulin and GLP-1.
Are peptides the same as steroids?
No. Peptides are amino-acid chains; steroids are a different class of molecules built on a ring structure.
Are all compounds in this library peptides?
No. A few, such as NAD+, AICAR, 5-Amino-1MQ, SLU-PP-332 and L-carnitine, are other types of molecules often discussed alongside peptides.
What is the difference between an FDA-approved peptide and a research peptide?
Approved products are reviewed for a specific use, manufactured under strict controls and come with labeling. Research-use-only products are not for human use and carry no such review.
Why does NVO separate research products from medical care?
Research materials and clinical treatment have different rules, evidence standards and safety requirements. Keeping them apart protects you and keeps information clear.
What does "studied in" mean in this library?
It tells you where the evidence comes from: lab cells, animals, small human reports or large clinical trials. Each level supports very different conclusions.
Does a certificate of analysis prove a product is safe?
No. A COA shows identity and purity for one batch. It does not show sterility (unless tested), safety or effectiveness.
Are peptides banned in sports?
Many are, including growth hormone, growth hormone secretagogues, IGF-1 analogues, BPC-157 and TB-500. Athletes should check the current WADA list.
Are peptides natural, and does that make them safe?
Many are copies or modifications of natural molecules, but natural origin does not make added amounts safe.
Can I combine peptides?
Almost no combinations have been tested. Combining compounds adds unknowns and makes it hard to tell what caused an effect.
Where can I get medical advice about peptides?
Talk with a licensed healthcare professional. NVO Health Guide content is educational and not medical advice. For prescription treatment, see Online Treatments, where independent licensed providers can evaluate you.