Roskilde University
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Roskilde, Denmark
Not yet recruiting
Effect of clonazepam and drug combination on driving ability in healthy adults with driving under the influence of drugs
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What is this trial about?
A plain-language summary of the goals, design and what participants do
The study examines how several commonly prescribed medicines affect a person's ability to drive safely. The medicines being tested are clonazepam, tramadol, pregabalin, gabapentin, dexamfetamine, and sodium oxybate. The condition of interest is Driving under the influence, which means impaired driving after taking a drug.
The main purpose is to determine how these drugs change driving performance. Participants will receive one of the study medicines or a placebo capsule and then, after a short waiting period, will complete a computer‑based driving simulation and a series of simple memory and reaction tests at specific times. Blood, saliva and other samples will be taken, and heart activity will be recorded with a ECG.
The driving simulation measures how well a person stays within the lane and how fast they travel. Cognitive tests include a digit span test (remembering numbers) and a reaction test (pressing a button quickly when a signal appears). Heart rhythm is monitored, and a mobile tool called the DRUID app records any feelings of impairment. Participants also answer short questionnaires about sleepiness and how they feel while driving.
The research process
The trial runs in 10 steps – from screening to follow-up. Each step says what happens and what the team monitors.
Who can join the trial?
7 criteria
- Age: You must be between 18 and 45 years old.
- Driving licence: You need a European driving licence that you have held for at least one year.
- Driving experience: You must have driven at least 200 kilometres (about 124 miles) in the past year.
- English language: You must be able to read and understand English.
- Vision: Your eyesight must be normal, or you must use glasses or contact lenses to correct it.
- Body mass index (BMI): Your BMI, a measure of weight compared to height, must be between 18.5 and 29.9.
- Blood pressure: Your blood pressure must be lower than 160/100 mmHg (the pressure of blood in your arteries; higher numbers can indicate hypertension).
Who cannot join the trial?
11 criteria
- You have a self‑reported history of traumatic brain injury, such as a major concussion.
- A pregnancy test is positive at the start of the study (women only).
- Your score on the Kennedy simulation sickness questionnaire (KSSQ) is higher than 30 after simulator training.
- You have a self‑reported diagnosis of neurological or psychiatric conditions, for example attention‑deficit/hyperactivity disorder.
- You report having any cardiovascular, gastrointestinal, hepatic, or renal disease, including high blood pressure (hypertension) or chronic lung disease.
- You are currently using any medications that affect driving ability or that could interact with the study drugs or alcohol.
- You consume more than 21 units of alcohol per week (high‑risk alcohol consumption).
- You smoke more than six cigarettes per day.
- You have a history of severe skin reactions such as Stevens‑Johnson syndrome, drug‑induced hypersensitivity syndrome, or a drug rash with eosinophilia and systemic symptoms after taking any of the study drugs.
- Your urine pH is outside the range of 4.5 to 8.0 at the beginning of the visit.
- You did not pass the required eye‑sight test.
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Investigated drugs
Clonazepam
is a medication that belongs to a group of drugs called benzodiazepines. In this study it is given by mouth to see how it might affect a person’s thinking, reaction time, and ability to drive safely. Researchers are watching for any changes in alertness, coordination, or judgment while participants take this drug.
Sodium oxybate
(often known as GHB) is a central nervous system depressant that is also taken orally. The trial uses it to understand whether it can cause drowsiness, memory problems, or slower decision‑making that could make driving more difficult. Participants are monitored for any signs of reduced alertness or impaired motor skills.
Dexamphetamine
is a stimulant medication that is taken by mouth. In the trial it is used to see if it can improve focus, speed of thinking, or reaction time, and whether any of these effects might make driving performance better or worse. Researchers watch for increased energy, restlessness, or changes in concentration.
Pregabalin
is a drug taken orally that is often used for nerve pain and anxiety. The study looks at how it might affect attention, coordination, and the ability to respond quickly while driving. Participants are observed for any feelings of dizziness, drowsiness, or reduced mental sharpness.
Gabapentin
is an oral medication commonly used for nerve pain and seizures. In this trial it is examined for its possible impact on thinking skills, reaction speed, and overall driving safety. Researchers check for side effects such as sleepiness, blurred vision, or slowed thinking.
Tramadol
(combined with paracetamol) is an oral pain‑relieving medication. The study evaluates whether it can cause drowsiness, affect coordination, or change a person’s ability to stay focused while driving. Participants are monitored for any signs of sedation, dizziness, or slower reaction times.
What is already known about the treatment
Clonazepam
This medication is taken by mouth as a tablet. It is an approved drug used for seizure control and anxiety relief and is listed in medical references as a benzodiazepine. It works by helping the brain chemical GABA calm down nerve activity. Pharmacologically it is classed as an anticonvulsant and anxiolytic.
Sodium Oxybate
This drug is taken orally, usually as a liquid solution. It is a legally approved treatment for cataplexy and excessive daytime sleepiness in narcolepsy and appears in medical literature as GHB. It acts by binding to specific brain receptors that increase the calming effects of GABA. It is classified as a central nervous system depressant.
Dexamfetamine
Dexamfetamine is swallowed as an oral capsule. It is an approved medication for attention‑deficit hyperactivity disorder (ADHD) and is recognized in the literature as a stimulant. It raises the levels of dopamine and norepinephrine, chemicals that help improve focus and activity. Its pharmacological class is a psychostimulant.
Pregabalin
Pregabalin is taken by mouth in capsule form. It is a licensed drug for nerve‑pain, fibromyalgia, and certain seizure types and is listed in medical references as an anticonvulsant. It binds to a part of calcium channels in nerve cells, which reduces the release of pain‑related chemicals. It belongs to the class of anticonvulsant/analgesic agents.
Gabapentin
Gabapentin is an oral capsule. It is approved for treating nerve pain and as an add‑on therapy for seizures, and is widely described in medical texts. It works by attaching to calcium channels on nerves, lowering the release of excitatory signals. It is classified as an anticonvulsant and analgesic.
Tramadol
Tramadol, combined with paracetamol, is taken as an oral tablet. It is an approved pain‑relief medicine used for moderate to severe pain and appears in medical literature as a weak opioid. It relieves pain by modestly activating opioid receptors and by increasing serotonin and norepinephrine levels. It is classified as an opioid analgesic combined with a non‑opioid analgesic.
Investigated diseases
Driving under the influence - Driving under the influence refers to the state in which a person operates a vehicle while impaired by alcohol, prescription medication, or other psychoactive substances. The impairment can reduce attention, slow reaction time, and affect coordination. As the concentration of the substance in the bloodstream rises, the degree of impairment typically increases, leading to greater deviation from normal driving patterns. The effects may persist for several hours after intake, gradually diminishing as the drug is metabolized. This condition is measured by changes in vehicle control, speed, and lane position.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2026-526362-24-00Estimated enrolment50 patientsSponsorKoebenhavns Universitet
sourced from the EU Clinical Trials Register and site verification
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