1. Pharmacokinetics describes what the body does to a drug, including absorption, distribution, metabolism and excretion. 2. Absorption is the process by which a drug enters the body through various routes of administration and is affected by characteristics like molecular size, lipid solubility, and ionization. 3. Drugs are distributed throughout the body and metabolized, especially in the liver and GI tract, which can reduce bioavailability through first-pass metabolism before reaching systemic circulation. 4. Metabolism involves phase I and II reactions that modify and conjugate drugs to make them more excretable, and excretion removes drugs and metabolites primarily through urine, bile, and feces.