Figure 5.

Combined presentation of age and genotype effects. The abscissa represents the age PK ratio representing the ratio of the systemic exposure in elderly over drug exposure in young given the same dose. The ordinate shows the genotype PK ratio representing the ratio of systemic drug exposure in the slowest metabolizer group (poor metabolizers if existing or intermediate metabolizer) over drug exposure in the normal metabolizer group. Four quadrants are highlighted illustrating the particular need to particularly consider age, genotype, or both parameters in therapy with the given drugs. The lines of 2 for age or genotype effect were highlighted because appropriate consideration of the respective factor in dosing would mean administering 50% of the standard dose only. Drugs in which both genotype and age ratios are above 2 may be of particular concern, but drugs above the 1.5 lines may also be of concern, depending on the therapeutic index of the respective drug.