What is peptide bioavailability (and why is it often low)?

Bioavailability is the proportion of a compound that reaches systemic circulation in an active form.

Many peptides have low bioavailability in certain routes because they can be:

• Broken down by enzymes (proteases/peptidases)
• Poorly absorbed across membranes
• Rapidly cleared

Bioavailability depends on the peptide, formulation, and route used in the study.