Therapeutic Drug Monitoring of Cariprazine – Updated Values for a Dose-Related Reference Range

Dose-related reference ranges can be used in therapeutic drug monitoring to monitor pharmacotherapy. The deviation of a measured serum concentration from the expected serum concentration at the corresponding dose can thus be identified early and responded to appropriately. The serum concentrations of patients treated with cariprazine regularly deviated from this dose-related reference range. As this is a relatively new drug with only one recommendation on values for a dose-related reference range, the values were tested for validity using real-world data.Serum concentrations of 24 patients receiving cariprazine once daily were analyzed retrospectively. Only patients without pharmacokinetic abnormalities were included. The measured serum concentrations were compared with the values of the dose-related reference range in the guidelines of the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie consensus guidelines of 2017 and checked whether a sufficient number of serum concentrations were within the dose-related reference range.Only 45.8% of the measured serum concentrations were within the dose-related reference range. The C/D ratio was 1.58±0.73. Accordingly, a lower value of 0.85 and an upper value of 2.31 were calculated for the updated dose-related reference range, which is below the currently recommended values.The results suggest that the current values for the dose-related reference range are too high and require adjustment. The updated dose-related reference range lies between 0.85 and 2.31, with a mean of 1.58±0.73.