Frequently asked questions

A peptide is a short chain of amino acids linked by peptide bonds. Peptides occur naturally as signalling molecules — insulin and oxytocin are both peptides — and synthetic versions are studied for their interaction with specific receptors.

Length and structure. Chains of roughly two to fifty amino acids are conventionally called peptides; longer chains that fold into stable three-dimensional shapes are called proteins. The boundary is a convention of usage rather than a strict rule.

Half-life is the time taken for plasma concentration to fall by half. It informs how frequently a compound is administered in study protocols, but it does not always predict duration of effect — some peptides accumulate in tissue and act beyond plasma clearance.

Sterile water containing approximately 0.9% benzyl alcohol as a preservative. The benzyl alcohol inhibits bacterial growth, which is why it is described in laboratory documentation for multi-access vials, in contrast to preservative-free sterile water.

Peptides hydrolyse in water over time and aqueous solutions can support microbial growth. Freeze-drying removes water and leaves a solid that remains stable far longer, which is why vials are supplied lyophilised and reconstituted only when needed.

Concentration equals the amount of peptide in the vial divided by the volume of solvent added. A 5 mg vial reconstituted with 2 mL gives 2.5 mg/mL. Every downstream volume figure depends on this number, which is why reconstitution volume must always be stated.

Handling documentation consistently describes refrigeration at 2–8 °C, protection from light, and avoidance of repeated freeze–thaw cycles. Usable windows after reconstitution are generally described in weeks rather than months.

Most are not. A small number, such as tirzepatide, have completed regulatory review for specific indications. The majority of compounds catalogued here are investigational or research-only, with evidence bases ranging from cell culture to early clinical trials.

Look at what type of study produced the finding. Cell culture and rodent work establish mechanism; randomised, blinded, controlled human trials establish clinical effect. A large animal literature with no human data is not strong human evidence.

No. PepDex is an educational reference summarising published research. Nothing on this site is medical advice, a recommendation, or a protocol, and no compound described here should be treated as a treatment for any condition.