Studying The Effects Of Drugs On Driving

Reducing the incidence of motor vehicle accidents (MVAs) caused by drug-impaired driving remains a critical public health priority. With over 20,000 FDA-approved medications currently on the market, many of which include psychoactive or sedative components, there is significant potential for some drugs to impair a person’s ability to safely operate a vehicle. Proactively identifying and evaluating medications that may increase the risk of MVAs is, therefore, an essential aspect of responsible and effective drug development.

Recognizing this concern, the U.S. Food and Drug Administration (FDA) released a draft guidance in 2015 outlining its expectations for evaluating the impact of new drugs on driving performance. Following public comment and feedback from industry stakeholders, the FDA finalized this guidance in November 2017 under the title Evaluating Drug Effects on the Ability to Operate a Motor Vehicle. The final guidance retained the core principles of the draft and established a clear framework for assessing potential driving impairment.

At the heart of the guidance is a tiered evaluation strategy that integrates pharmacological and toxicological profiling, epidemiological data, and standardized behavioral assessments. This framework encourages developers to begin assessing potential effects on driving ability early in clinical development, moving beyond reliance on self-reported cognitive adverse events, which had traditionally been the norm in early-phase trials. Instead, the guidance calls for objective, direct measurement of drug effects on cognitive and psychomotor function where warranted.

Importantly, the guidance does not impose a one-size-fits-all requirement. Whether a drug needs to undergo this tiered evaluation depends heavily on its intended use and target population. For example, drugs administered in controlled settings, such as anesthetics used during surgery, may not require comprehensive driving-related assessments, provided pharmacokinetic data confirm that drug concentrations are negligible by the time patients are discharged. In contrast, drugs intended for chronic or intermittent outpatient use, particularly in adult populations who are likely to drive, are more likely to necessitate rigorous evaluation, regardless of whether the drug is classified as psychoactive.

While the guidance places particular emphasis on psychoactive substances, it also underscores the importance of considering non-psychoactive drugs, which may indirectly impair driving ability through effects such as drowsiness, dizziness, or delayed reaction time. As such, developers must exercise careful judgment when designing studies to ensure the safety of patients and the broader public and to meet regulatory expectations.