Absorption is the process by which a drug enters the bloodstream from its site of administration.

The rate and extent of drug absorption can be influenced by factors such as drug formulation, route of administration, and physiological factors (e.g., pH, blood flow, surface area).

Distribution is the process by which a drug moves from the bloodstream to various tissues and organs in the body.

The distribution of a drug can be influenced by factors such as protein binding, tissue perfusion, and the blood-brain barrier.

Metabolism is the process by which a drug is chemically modified by enzymes in the body.

Cytochrome P450 enzymes are primarily responsible for the metabolism of drugs in the liver.

Excretion is the process by which a drug and its metabolites are removed from the body.

Renal excretion is the primary pathway for the excretion of drugs and their metabolites.

Pharmacokinetics is the study of the relationship between the concentration of a drug in the body and time.

Half-life is the time it takes for the concentration of a drug in the body to decrease by half.

Drug-drug interactions occur when two or more drugs interact with each other, resulting in altered drug effects.

Drug-drug interactions can occur through various mechanisms, including induction or inhibition of drug-metabolizing enzymes, alteration of drug transport, and displacement from protein binding sites.

Pharmacodynamics is the study of the relationship between drug concentration and its effects on the body.

The pharmacodynamic response to a drug can be influenced by factors such as drug concentration, receptor affinity, and signal transduction pathways.

Adverse drug reactions are adverse reactions to a drug that are not related to its intended pharmacological effects.