Phenytoin and Driving Safety
Recruitment status was: Recruiting
Driving Simulator Performance
|Study Design:||Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Investigator)
|Official Title:||Phenytoin and Driving Safety|
- Number of driving simulator crash events [ Time Frame: Open-ended ]
- Measures of cognition assessed in the on-phenytoin condition [ Time Frame: Open-ended ]
|Study Start Date:||August 2005|
|Estimated Study Completion Date:||December 2008|
|Estimated Primary Completion Date:||December 2008 (Final data collection date for primary outcome measure)|
Phenytoin will be dosed to a target dose of 5 mg/kg qhs for one month
Other Name: Dilantin
Patients with epilepsy are at elevated risk for automobile crashes, causing great personal suffering and financial costs to society. Most collisions involving epileptic drivers are not seizure related but may instead result from cognitive effects upon driving performance of epilepsy and antiepileptic drugs (AEDs). Several million American drivers take AEDs for treatment of medical conditions besides epilepsy and may also be at risk for cognitive impairments that can reduce driving performance. Empirical evidence of the effects of AEDs on driving performance would enable development of driving guidelines that could lower the risk of injurious motor vehicle collisions; however, this evidence is currently lacking.
The broad goal of the current project is to determine the specific effects of AEDs on cognitive function and driving performance. To address this goal we will assess driving performance and cognitive abilities in neurologically normal volunteers taking phenytoin (Dilantin), the most commonly prescribed AED. Effects of phenytoin on driving performance and cognition will be addressed in a randomized, double-blind, placebo-controlled, crossover study. Driver cognition will be assessed using a battery of neuropsychological tests. Driving performance will be objectively assessed in all participants on standardized tasks enacted in a state-of-the-art driving simulator. Our 3 Specific Aims are:
Aim 1: To assess the effects of phenytoin on cognitive abilities that are crucial to the driving task, including perception, attention, memory, and executive function.
Hypothesis 1: A driver's cognitive abilities will decline during steady-state phenytoin administration compared to placebo. Drivers with higher blood levels of phenytoin will show greater decline.
Aim 2: To assess effects of phenytoin on driving performance and safety errors in a state-of-the-art driving simulator.
Hypothesis 2: Driving performance will decline and driver safety errors will increase during phenytoin administration compared to placebo. Drivers with higher blood levels of phenytoin will show greater impairments of driving.
Aim 3: To assess the effects of phenytoin-related cognitive impairments upon driving performance in a state-of-the-art driving simulator.
Hypothesis 3. Impairments of cognitive function affecting perception, attention, memory, executive function, and arousal will increase the likelihood of driver errors that may lead to a crash.
Our hypotheses would be supported if the drivers taking phenytoin, as opposed to placebo, demonstrate worse cognitive performance on neuropsychological tests, and more safety errors and crashes in the simulator. The hypotheses would also be supported if drivers with higher phenytoin levels show greater impairments of cognition and driving. Once the effects of phenytoin on driving performance are demonstrated in this project, we will have evidence to support more comprehensive research addressing specific dosing and serum levels and acute versus chronic administration.
There is currently no evidence concerning the effects of phenytoin on driving performance. Accurate driving performance data on patients receiving phenytoin would allow determination of fair and accurate criteria for making recommendations to drive or not to drive affecting millions of patients taking AEDS for epilepsy and other conditions. These data could also help reduce the risk of car crashes due to medication side effects.
Please refer to this study by its ClinicalTrials.gov identifier: NCT00581893
|United States, Iowa|
|University of Iowa Hospitals and Clinics|
|Iowa City, Iowa, United States, 52242|
|Principal Investigator:||Erik K St. Louis, M.D.||University of Iowa|