Check it yourself
Everything on this site is built from public sources. These are the same ones, so you never have to take our word for a tier, a mechanism, or a regulatory status.
Where to look things up
Terms you will meet
Plain definitions, in the sense the literature actually uses them.
Agonist
Binds a receptor and activates it, producing the same class of response as the natural ligand.
Antagonist
Binds a receptor and blocks it, preventing the natural ligand from acting. Same pocket, opposite result.
Affinity
How tightly a molecule binds its target. Says nothing about whether that binding produces an effect.
Efficacy
How large a response the binding produces. A high-affinity molecule can have zero efficacy.
Bioavailability
The fraction of an administered dose that reaches systemic circulation intact. Oral bioavailability for most peptides is close to nil.
Half-life (t½)
Time for plasma concentration to fall by half. Determines dosing frequency more than anything else.
SPPS
Solid-phase peptide synthesis. Building a chain on a resin bead so excess reagents can be washed away each cycle.
Lipidation / acylation
Attaching a fatty acid so the peptide binds albumin and circulates far longer.
PEGylation
Attaching polyethylene glycol to increase effective size and slow renal filtration.
DPP-4
Dipeptidyl peptidase-4. An enzyme that clips two residues off many peptide hormones within minutes.
GPCR
G-protein coupled receptor. The seven-transmembrane receptor family most therapeutic peptides act on.
Secretagogue
A substance that prompts the body to release its own hormone, rather than supplying that hormone directly.
Endotoxin
Bacterial cell-wall fragment that provokes fever and inflammation. Present even when no live bacteria remain.
Net peptide content
How much of a vial's labelled weight is actually peptide, after water and counter-ions. Frequently unstated.
Surrogate endpoint
A measurable marker standing in for the outcome you care about. Moves more easily than the outcome does.
Pre-registration
Publishing a study's design and primary endpoint before collecting data, so the analysis cannot be tailored to the result.
Compounding
A pharmacy preparing a medicine for an individual patient. Oversight and quality vary widely by jurisdiction.
Research use only
A legal designation meaning not for human use. Carries no requirement for pharmaceutical-grade manufacture.
What the risk actually consists of
Not a warning list for its own sake: these are the specific mechanisms by which harm has been documented.
Identity and contamination
Regulatory agencies in several countries have issued alerts after testing unlicensed injectable products and finding the wrong peptide, the wrong quantity, or bacterial contamination. Without independent batch testing, the vial's contents are an assumption.
Sterility and injection route
Anything injected bypasses every barrier the body has. Documented harms from non-sterile injecting include abscess, cellulitis, and bloodstream infection, outcomes that have nothing to do with the intended pharmacology.
Unmonitored physiological effects
Peptides that alter growth hormone, glucose handling or immune signalling change parameters a clinician would normally monitor. Without that monitoring, a developing problem has no way of being detected early.
Legal and competitive exposure
Import, possession and supply rules differ sharply between countries. Separately, many peptides appear on the WADA list, where sanctions apply irrespective of whether a substance is legal where an athlete lives.
If you are considering anything in this library for yourself
Take the question to a qualified clinician who can see your history, current medications and bloods. That is not a formality to get past. Interactions and contraindications are individual, and no reference site can assess them. If a peptide is approved for your indication, it is available through that route with monitoring attached.
Reading list
| Area | Why it matters | Level |
|---|---|---|
| Peptide drug discovery reviews | Broad surveys of what has been approved, what failed, and the reasons given at the time. | Introductory |
| Solid-phase synthesis methodology | Explains where impurities originate and why particular sequences are difficult to make cleanly. | Technical |
| GPCR structural biology | How binding pockets differ between related receptors, the structural basis of selectivity. | Advanced |
| Pharmacokinetic modelling | Turns half-life and clearance numbers into an understanding of what a dosing interval means. | Technical |
| Clinical trial methodology | The single highest-leverage subject here. Most peptide misinformation is a trial-design misreading. | Introductory |
| Regulatory science | Why approval takes the shape it does, and what a rejection document actually tells you. | Introductory |