Enzyme inhibition and induction

Abstract 

Enzymes fulfil the role of biological catalysts. One important family of enzymes in medicine and anaesthesia is the cytochrome P450 superfamily, which are involved in the metabolism of drugs. Although enzymes are recovered unchanged at the end of a reaction, their function can be inhibited or induced, which causes alterations in their ability to catalyse a reaction. These changes are often a consequence of the action of a particular drug or exogenous compound on the enzyme. Induction may occur due to increased expression of the enzyme following an increase in messenger RNA translation precipitated by activation of an intracellular cytosolic receptor. Inhibition may occur when a drug inhibits binding of substrate to an enzyme’s active site. Concurrent administration of two or more drugs may lead to one drug affecting the action of the other. Addition and summation describe a combined effect of two administered drugs equal to the effect of the simple sum of the effects of the individual drugs. Synergism and potentiation describe a supra-additive effect when drugs are combined. Subtraction occurs when two drugs are less effective in combination. Subtraction is often referred to as antagonism.

Keywords: addition, cytochrome P450, induction, potentiation, synergism