Guideline for evaluating the effects of psychotropic drugs on motor vehicle driving performance in Japan: A tiered approach for the assessment of clinically meaningful driving impairment

Abstract In December 2022, the Ministry of Health, Labour and Welfare (MHLW) of Japan issued and implemented the guideline for evaluating the effects of psychotropic drugs on motor vehicle driving performance. This guideline recommends the use of a tiered approach to assess clinically meaningful driving impairment. It is noted that adverse events cannot be solely explained by pharmacokinetics, as the onset and duration of these events vary. Among these adverse events, those affecting alertness, such as drowsiness caused by psychotropic drugs on driving performance, are more frequently observed during initial treatment stages and dose escalation. Hence, when evaluating the effects of psychotropic drugs on driving performance, it becomes crucial to assess the persistence of clinically meaningful impairment. Therefore, the MHLW guideline, developed by the authors, emphasizes the need to assess the temporal profile of adverse events affecting driving in all clinical trials. Additionally, the guideline states that when conducting driving studies, the timing of multiple dosing should consider not only the pharmacokinetics of the investigational drug but also its tolerance.