[Pharmacokinetics from the viewpoint of the clinical anesthetist]

Pharmacokinetics describes the time-depend course of plasma concentration of a drug. Pharmacodynamics describes the pharmacological effect of the substance. Both together form the pharmacological model used in clinical practice. The global descriptors total clearance Cltot, volume of distribution Vd, and half-life t1/2 allow for a first good approximation of drug delivery and a characterisation of drugs. Unwanted side-effects such as inadequate anaesthesia or prolonged recovery periods may be explained. The main clinical use of pharmacokinetics is to sustain dosing schemes based on scientific data. It also may be helpful in creating new administration schemes especially for continuous infusion of intravenous hypnotics or analgetics. New developments such as Target-Controlled Infusion (TCI) are based on pharmacokinetic data and computations and may be an improvement for the clinically working anaesthetist.