Cytochromes P450, Drugs, and Diseases

Significance of unexpectedly low metabolism of a drug by P450s. The typical pattern seen with the majority of the population (extensive metabolizers) is shown in the upper panel, where the plasma level of the drug is maintained in a certain range over the period of several consecutive doses (arrows indicate multiple doses). Unusually slow metabolism (lower panel) occurs when a poor metabolizer (without previous knowledge of phenotype) receives the same dose, resulting in an elevated plasma level of the drug. Adapted from (30).