Bioavailability

Last updated August 2026

The fraction of a dose that reaches circulation in active form. Injected peptides have high bioavailability; most peptides are poorly absorbed if swallowed, which is why they are usually injected.

This is the practical reason nearly all research peptides are injected rather than taken by mouth: digestive enzymes break peptide bonds, so an oral dose largely never reaches circulation intact. Subcutaneous injection sidesteps that, delivering most of the dose in active form. It also explains why oral or nasal formulations, when they exist, are dosed very differently from the injectable amounts a reconstitution calculator assumes.

Educational reference only — not medical advice. Always follow the guidance of a qualified healthcare professional.