Pharmacokinetics and pharmacodynamics of psychoactive drugs in old age

It can be shown that aged patients need about 2/3 of the dose of younger adult depressive patients to reach a comparable serum level distribution. No difference could be found between younger and aged patients in the correlation between serum level and clinical outcome. This correlation can best be described as a kind of saturation curve. Taking the vast serum level range in patient collectives in therapy with tri- and tetracyclic antidepressives into consideration, a routine screening of serum levels of antidepressives is highly desirable.