How Peptides Work in the Body

Peptides exert their effects through receptor binding. When a peptide molecule reaches its target receptor on a cell surface, it fits like a key in a lock, triggering an intracellular signaling cascade. This cascade amplifies the signal through second messengers like cyclic AMP (cAMP), leading to changes in gene expression, protein synthesis, or enzyme activity. The specificity of this receptor-ligand interaction is what gives each peptide its unique biological profile.

Bioavailability is a critical concept in peptide science. Because peptides are made of amino acids, they are broken down by digestive enzymes (pepsin, trypsin, chymotrypsin) if taken orally. This is why research peptides — including BPC-157 — must be administered via subcutaneous injection, which delivers the compound directly into the tissue beneath the skin, bypassing the digestive system entirely. Some non-peptide compounds like MK-677 are designed for oral use, and certain peptides are available intranasally, but oral peptide capsules are generally ineffective.

The half-life of a peptide determines how long it remains active in your body. Some peptides like BPC-157 have relatively short half-lives of a few hours, requiring multiple daily administrations for sustained effect. Others, like CJC-1295 with DAC (Drug Affinity Complex), have been engineered with extended half-lives lasting days. Understanding half-life is essential for proper dosing and timing of any peptide protocol.