Topic overview

Start with the big picture

This introduction distinguishes biopharmaceutics from pharmacokinetics and connects both fields to drug product performance. It introduces bioavailability as the fraction of a dose that reaches systemic circulation, and bioequivalence as a comparison of products using exposure measures. Key pharmacokinetic parameters—including Cmax, Tmax, AUC, half-life, clearance, and volume of distribution—help describe drug concentration over time. For oral medicines, absorption may be limited by dissolution or permeability. The lesson also previews how formulation and physiological factors affect absorption, how the Biopharmaceutics Classification System organizes drugs by solubility and permeability, and how dissolution, membrane transport, ionization, and in-vitro–in-vivo relationships help explain observed drug behavior.