Castberg I, et al. – The reason for this examination was to study serum concentrations of second–generation antipsychotics in relation to age and gender in a population ranging from 18 to 100 years. It was found that the impact of age on the serum concentrations of the antipsychotics studied becomes pronounced with advanced age. The authors suggested that the patient population aged above 70 should be subdivided according to exact age, and considerable dose reductions are recommended.

Methods

• For this purpose, results from a routine therapeutic drug monitoring database were retrieved, and 43079 samples from 11968 patients were incorporated (17 249 samples for clozapine, 16171 samples for olanzapine, 5343 samples for risperidone, and 4316 samples for quetiapine).
• The dose-adjusted concentration was utilized as the primary target variable.
• A linear mixed model was utilized to allow the inclusion of multiple samples from every patient.

Results

• Age significantly affected the concentrations of all 4 drugs.
• At the age of 80, the dose-adjusted concentrations were up to twice those of the age of 40.
• Dose-adjusted concentrations were 2- to 3-fold higher at the age of 90.
• It was found that age-related increases were largest for clozapine (+108% at 80 years; +197% at 90 years) and smallest for olanzapine (+28% at 80 years; +106% at 90 years).
• The results of this study showed that females generally had dose-adjusted concentrations 20–30% higher than males.