The transfer of compound from the site of administration to the total systemic circulation and then to the various tissues of the body is called distribution . Metabolism is the enzymatic conversion of one chemical species to another. Elimination is the removal of compounds from the body via a number of pathways, primarily through urine and bile. The BBB partition coefficient measures the ratio of the concentrations of a drug in the brain and blood compartments. Quantum chemistry provides an understanding of chemical reactions at the atomic level.
Empirical approaches provide an understanding based upon experimentation and observation.
Drug Metabolism Drug metabolism is the process by which xenobiotics are transformed, mainly in the liver, from one form to another. Intestinal Absorption Absorption generally refers to the amount of drug compound that enters the portal vein following oral administration.