Pharmacokinetics – Drug absorption and distribution

Pharmacokinetics explained: learn ADME fundamentals—absorption, bioavailability, first-pass metabolism, and distribution—to understand how drugs enter, move through, and reach target tissues. This video dives into absorption routes (oral, IV, sublingual, IM, subcutaneous, transdermal), bioavailability concepts, and why first-pass liver metabolism and formulation, food, and gastric emptying change drug effectiveness. You’ll learn practical clinical implications—why IV gives 100% bioavailability and rapid onset, when sublingual dosing (eg, GTN for angina) avoids first-pass loss, and when oral drugs need higher doses due to reduced systemic exposure. The distribution segment explains how blood flow, lipid solubility, protein binding, and biological barriers (blood–brain barrier, placenta, breast milk) determine where drugs go, which tissues are affected, and which molecules remain in plasma. Key technical terms—bioavailability, first-pass metabolism, protein binding, blood–brain barrier, volume of distribution (Vd)—are clearly defined with clinical examples (warfarin, heparin, digoxin). By the end, you’ll be able to predict how route, formulation, and patient factors alter onset, potency, and risk, and apply that knowledge to dosing and route selection. Watch to gain a concise, clinically focused foundation in pharmacokinetics that makes drug choice and administration clearer—stay tuned for part two covering metabolism and excretion.