[P-450 cytochromes and mono-oxygenases. Mechanism of action. Consequences in pharmacology and toxicology (author's transl)].

The mechanism of action of mono-oxygenases of the biotransformation system of exogenic compounds is described emphasising two characteristics which are at the root of the implications of this system in pharmacology and toxicology : its non-specificity with regard to substrates and its great chemical reactivity. The consequences of the biotransformation of a drug (modulation of its therapeutic effect, appearance of noxious side-effects due to the formation of reactive metabolites) are illustrated by a few examples. Finally, the various mechanisms by which a drug may modify biotransformation and the effects of a second drug given in association, are analysed.