Evaluating and Determining the Effects of Psychotropic Drugs on Motor Vehicle Driving Performance: Key Considerations of the Japanese Guideline and Criteria for Clinical Implementation of Evidence

The cross-national differences in automobile driving precautions stated in psychotropic drug package inserts primarily reflect regulatory policies and insufficient evaluation method standardization until recent years, rather than intrinsic ethnic differences. In January 2025, the Ministry of Health, Labour and Welfare (MHLW) of Japan issued the Criteria for Determining the Effects of Psychotropic Drugs on Motor Vehicle Driving Performance. These criteria were published as an appendix to an earlier guideline for evaluating these effects published in December 2022. These guidelines and criteria, developed by the authors, provide methods for evaluating the effects of psychotropic drugs. However, these are not intended to assess the fitness of an individual patient to drive. The MHLW guideline and criteria recommend a tiered approach for assessing clinically meaningful driving impairment. Adverse events affecting alertness, such as drowsiness, caused by psychotropic drugs on driving performance are more frequent during the initial treatment stages and dose escalation. Therefore, evaluating the effects of psychotropic drugs on driving performance requires careful consideration of the persistence of clinically meaningful impairment. Additionally, understanding the magnitude and duration of such effects is crucial for selecting appropriate treatments and offering effective guidance to patients. The MHLW criteria categorize the effects of psychotropic drugs on driving performance into four levels based on their magnitude and duration. Furthermore, the MHLW criteria could help to determine which clinical trials are necessary to evaluate the persistence of clinically meaningful impairment. Namely, the MHLW criteria could be used to structure the substantial evidence needed for evaluating the effects on driving performance for approval applications and clinical implementation.