The US Food and Drug Administration (FDA) on Tuesday finalized guidance on how drugmakers should study the effects of their drugs on driving ability.
The guidance is largely in line with the draft version issued in 2015, and continues to recommend that drugmakers follow the "tiered assessment" approach detailed in a 2011 report from the National Highway Traffic Safety Administration's Office of Behavioral Safety Research.
FDA first introduced the draft guidance after issuing safety alerts over concerns that certain sleep medications, such as Ambien (zolpidem) and Lunesta (eszopiclone), could cause impaired driving the next day.
The tiered assessment approach recommended by FDA consists of a pharmacology/toxicology review, epidemiology review and a clinical/standardized behavioral assessment.
"With this approach, sponsors can use drug information obtained early in development to guide the need to collect data later in development related to driving impairment potential," FDA writes, adding that this can help drugmakers avoid wasting resources evaluating drugs with little potential for impairing driving or drugs that are obviously impairing, such as surgical anesthetics.
FDA also says that drugmakers should focus on five broad functional domains important to driving ability:
- Attention and processing speed
- Reaction time/psychomotor functions
- Sensory-perceptual functioning
- Executive functions
According to FDA, drugs intended for chronic, or chronic-intermittent outpatient use are the most likely to require driving studies, while drugs meant primarily for pediatric or inpatient hospital use would not need driving studies.
When driving studies are needed, FDA says those with actual vehicles or driving simulators can be used, though sponsors should weigh the advantages and disadvantages of either type of study and discuss any concerns with the appropriate review division at FDA.
FDA says it's important that drugmakers consider a range of factors that could impact driving for each drug, as some drugs may have effects that could both improve and worsen driving ability. For example, central nervous system (CNS) stimulants may make a patient feel more alert, but can also increase risk-taking behavior.
While the guidance is focused on psychoactive drugs, FDA says that drugmakers need to consider effects that could impair driving for nonpsychoactive drugs as well. For instance, FDA says that patients could experience impaired consciousness as a result of a hypoglycemic reaction from glucose-lowering drugs or blurred vision from mydriatic eye drops.
Though the approaches for evaluating driving ability may differ for psychoactive and nonpsychoactive drugs, FDA says the approach should be selected based on drug-specific effects.
"Sponsors also may need to conduct driving studies if an active moiety approved for a particular use is proposed for a different indication, at a different dose or dosing schedule, or in a new patient population in which there is insufficient information about how the drug may affect driving ability," FDA writes.
FDA also acknowledges that driving impairment studies "may be impossible to conduct in the intended patient population or may need modification for drugs associated with serious safety risks that prevent enrollment of healthy subjects." In such situations the agency says that sponsors may be able to address the risk of driving impairment through a combination of the data they are able to collect and labeling provisions to address any uncertainty.