The document discusses the key aspects of pharmacokinetics including absorption, distribution, metabolism, and excretion of drugs in the body. It describes how drugs are absorbed via mechanisms like passive diffusion, active transport, and endocytosis. Factors like molecular weight, concentration gradients, and membrane permeability influence absorption rates. Most drug absorption occurs in the small intestine. Distribution of drugs depends on blood flow, ability to cross membranes, and plasma protein binding. The liver plays a major role in drug metabolism through phase I and phase II reactions, converting lipophilic drugs into more polar and water-soluble compounds that can be excreted.

9. Absorption of drugs by various mechanisms