[Bioavailability and its significance in pharmacotherapy].

The paper provides an overview of information related to bioavailability, including the fundamental notions and the factors, which can change this parameter described in quantitative way drug absorption--one of the processes involved in fate of drug in the organism. Systemic bioavailability is best described by the measurement of the relative amount of an administered dose that reaches the general circulation (Area Under the Curve, AUC), the maximum concentration achieved (Cmax), and the time (tmax) at which this occurs. Liver diseases may substantially increase the oral bioavailability of drugs that are subject to extensive first-pass metabolism e.g. pro-pranolol, lidocaine, metoprolol, verapamil. To avoid toxicity, oral doses of these drugs need to be reduced in patients with severe liver diseases.