Population pharmacokinetics as a method to detect variable risperidone exposure in patients suffering from dementia with behavioral disturbances

Objective: This study was intended to compare the consistency of risperidone exposure in patients who have dementia and behavioral disturbances treated in a psychiatric hospital versus a community care setting. Methods: Population pharmacokinetic modeling was used to assess the consistency of risperidone exposure in Alzheimer's disease patients with agitation. The ratio of predicted to observed drug concentrations (C_pred/C_obs) derived from this model was used to compare exposure in the inpatient versus long-term/home care settings using both the mean and the variance of this term across groups. Results: The modeled C_pred/C_obs ratios had a much higher within-subject variance in the inpatients than in the community care patients (117.03% vs 72.35%; P < 0.001). The central tendencies of the C_pred/C_obs ratios across the 2 groups were not significantly different. Conclusions: Exposure to risperidone was more variable in a psychiatric hospital than in a community care setting. Future research may help to identify the specific contributors to the increased variance observed in this pilot study.