The document discusses the processes the body undergoes to metabolize drugs, including absorption, distribution, metabolism, and elimination. It describes various routes of drug administration like oral, intravenous, intramuscular, and subcutaneous. Oral administration is the most common but can be affected by food intake. Intravenous administration enters distribution directly without first pass metabolism. Different mechanisms underlie drug absorption, including passive diffusion, facilitated diffusion, active transport, and exocytosis/endocytosis.