ABSTRACT
Pharmacokinetics is the study of those rate processes involved in the absorption, distribution, metabolism, and excretion of drugs and their relationship to the pharmacological, therapeutic, or toxic response in animals or humans. In 1937 Teorell published two theoretical papers which are regarded as a classic treatise marking the beginning of what is called pharmacokinetics. Pharmacokinetic techniques attempt to madiematically define the time course for drug in the body by assaying for drug and metabolites in readily accessible fluids such as blood and urine. Pharmacokinetic studies probably date back to 1924, when Widmark and Tandberg published two theoretical papers on the one-compartment open model. If drug disposition is biexponential, then the kinetics require the sampled compartment to reversibly transfer drug to at least one other compartment with one or both compartments giving rise to elimination pathways. The biological half-life is the time necessary to decrease the drug concentration assayed in plasma, blood, or serum by a half during the "elimination" phase.
