A pilot, randomized, open-label trial assessing safety and pharmakokinetic parameters of co-administration of rivastigmine with risperidone in dementia patients with behavioral disturbances

Background: The majority of patients with Alzheimer's disease (AD) or vascular dementia display, in addition to cognitive impairment, various degrees of behavioral disturbances. As the use of cholinesterase inhibitors for the treatment of cognitive impairment in dementia becomes widespread, many of these patients will be treated concomitantly with cholinesterase inhibitors and with anti-psychotic drugs to ameliorate behavioral disturbances. Despite the widespread use of this combination in clinical practice, the safety and tolerability of such combination therapy has not been evaluated in controlled clinical trials. This pilot study examined the effects of addition of risperidone 0.5-2 mg/day to patients on rivastigmine 3-12 mg/day, and vice versa. Methods: 65 patients suffering from AD, 10 from vascular dementia, and 15 from both were randomized to open label rivastigmine and risperidone, alone or in combination, for 20 weeks. Adverse events caused by co-administration were assessed. Results: No clinically relevant adverse interactions were observed. Conclusions: These preliminary results indicate that rivastigmine and risperidone can be safely co-administered. Confirmation of these results in large clinical trials studies is warranted.