[The biotransformation of inhalation anaesthetics and its relevance to clinical side effects (author's transl)].

The volatile anesthetics are not inert substances, but they are metabolised by means of a non-specific drug metabolizing enzyme system of the liver. Thus, in combined administration of several drugs, the knowledge of the metabolic pathways and the influence of the anesthetics on the transforming system is not only theoretically important, but represents a conditio sine qua non to the anesthesist as regards the handling of modern anesthetics. The occasionally observed liver and kidney injuries indicate a potential formation of toxic metabolites. Renal damage due to methoxyflurane may be caused by F- which is released during its biotransformation while, in the group of halogenated inhalation anesthetics, only chloroform is a true hepatotoxic substance. The explanation of the liver damage which is rarely observed after halothane administration, is an open question till now. For this, the investigator must go back to animal experiments where the quantity and quality of the metabolism differ considerably from one species to the other. In men it is widely unknown to what extent the microsomal enzymatic system is influenced by the disease itself and/or by the pharmacotherapy. Therefore great efforts must still be made in order to establish the formation of side-effects of halogenated inahlation anesthetics and, thus, to improve their therapeutic safety.