Pharmacokinetics Overview

First-pass effect

• Metabolism of drug in liver before reaching systemic circulation

• Absorption of drug in the stomach

• Excretion of drug through the kidneys

• Distribution of drug throughout the body

Steady-state concentration

• Drug intake equals drug elimination

• Drug intake exceeds drug elimination

• Drug elimination exceeds drug intake

• Drug concentration remains constant regardless of intake

Pharmacokinetics

• Study of drug movement through the body - ADME

• Study of drug interactions in the body

• Study of drug effects on the body

• Study of drug manufacturing processes

Drug interaction

• Effect of one drug altered by another drug

• A method to enhance drug absorption

• A type of drug overdose

• A reaction that causes drug resistance

Half-life (t_{1/2})

• Time for plasma concentration of drug to reduce by half of its original value

• Time taken for a drug to reach its maximum concentration

• Time required for a drug to be completely eliminated from the body

• Time for the body to metabolize a drug by 50%

Cytochrome P450

• Enzyme family involved in drug metabolism

• Protein involved in DNA replication

• Hormone receptor in cell signaling

• Transport protein for fatty acids

Absorption

• Process of drug entering the bloodstream

• Process of drug being metabolized in the liver

• Process of drug being excreted from the body

• Process of drug binding to receptors

Distribution

• Dispersion of drug throughout body fluids and tissues

• The process of drug absorption into the bloodstream

• The elimination of drugs from the body

• The chemical transformation of drugs in the liver

Metabolism

• Chemical alteration of drug in the body

• Absorption of nutrients in the digestive system

• Excretion of waste products from the body

• Conversion of food into energy

Maintenance dose

• Dose to maintain steady-state concentration

• Initial dose to achieve therapeutic effect

• Dose given to counteract side effects

• Dose that is adjusted based on patient weight