Alcohol + THC for DUI Effects

(THC-ETOH-I Trial)

Overseen By Laura Cadavid, BS

Age: 18 - 65

Sex: Any

Trial Phase: Phase 1

Sponsor: Yale University

Disqualifiers: Cannabis naïve, Alcohol naïve, Pregnancy, Hearing deficits

Compensation: Varies

Number of Visits: 1

Duration: 1 day

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to understand how alcohol and THC (the main active ingredient in cannabis) affect driving skills and thinking. Participants will receive either actual or placebo versions of inhaled delta-9-THC and oral ethanol to assess their impact on simulated driving. The trial seeks individuals who have occasionally used cannabis and have consumed at least two alcoholic drinks in their lifetime.

As a Phase 1 trial, the research focuses on understanding how the treatment works in people, offering participants a chance to contribute to groundbreaking research.

Do I need to stop taking my current medications to join the trial?

The trial information does not specify whether you need to stop taking your current medications.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research has shown that both THC (the active ingredient in marijuana) and alcohol affect driving and thinking. When people use THC, about half may not realize its impact on their driving. Alcohol is well-known for impairing judgment and slowing reflexes.

Studies have found that some individuals who used both substances together had only small amounts of THC in their blood, suggesting minimal use, yet they were still affected. Most importantly, combining THC and alcohol can intensify these effects, impacting driving and thinking more than when used alone.

Both substances are commonly used, and many people manage them well in social settings. However, for safety, it is crucial to remember that combining them can be risky, especially when driving. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Researchers are excited about these treatments for DUI effects because they explore how active inhaled delta-9-THC and active oral ethanol affect driving abilities when used together or separately. Unlike standard DUI evaluations that focus on alcohol alone, this study examines the combined impact of alcohol and THC, which is becoming more relevant as cannabis legalization spreads. The unique aspect is the investigation of inhaled THC, which may have different effects on impairment compared to traditional smoked or edible cannabis products. Understanding these interactions could lead to more accurate and comprehensive DUI assessments in the future.

What evidence suggests that this trial's treatments could be effective for DUI effects?

This trial will examine the effects of different combinations of THC and alcohol on driving ability. Research has shown that inhaling delta-9-THC, a compound from cannabis, can impair driving ability. One study found that most driving skills return to normal about 5 to 7 hours after using 20 mg of THC. In contrast, alcohol is a well-known cause of road accidents, significantly increasing the risk of crashes and the likelihood of arrest if over the legal blood alcohol limit. This trial includes arms where participants receive active THC and placebo ethanol, active THC and active ethanol, placebo THC and active ethanol, and placebo THC and placebo ethanol. Using THC and alcohol together may increase driving risks, as both substances can impair judgment and reaction time. These findings suggest that combining THC and alcohol can lead to significant driving problems. ^{6 7 8 9 10}

Are You a Good Fit for This Trial?

This trial is for occasional cannabis users aged 21-55 who have drunk alcohol at least once. They must understand the study and agree to participate. People can't join if they've never used cannabis or alcohol, have hearing problems, or are pregnant.

Inclusion Criteria

Occasional current cannabis users

I am between 21 and 55 years old.

Experience with drinking 2 or more standard drinks of alcohol at least once in lifetime

Exclusion Criteria

Cannabis naïve

Alcohol naïve

Positive pregnancy screen

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Treatment

Participants receive oral ethanol and vaporized THC to study their effects on simulated driving and cognition

1 day

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

1 week

What Are the Treatments Tested in This Trial?

Interventions

• Active inhaled delta-9-THC
• Active Oral Ethanol
• Placebo

Trial Overview The study aims to understand how ethanol (found in alcoholic drinks) and delta-9-THC (from cannabis) affect simulated driving and thinking skills. Participants will either receive active oral ethanol, a placebo, or inhale active THC.

How Is the Trial Designed?

Group I: Placebo THC and Active Ethanol Experimental Treatment 2 Interventions

Group II: Active THC and Placebo Ethanol Experimental Treatment 2 Interventions

Group III: Active THC and Active Ethanol Experimental Treatment 2 Interventions

Group IV: Placebo THC and Placebo Ethanol Placebo Group 1 Intervention

Who Is Running the Clinical Trial?

Yale University

Lead Sponsor

Trials

1,963

Recruited

3,046,000+

Published Research Related to This Trial

The study found that combining ethanol and marihuana significantly worsened psychomotor performance, particularly skills needed for driving, indicating an additive or synergistic effect on impairment.

Interestingly, taking ethanol before smoking marihuana did not significantly affect subjective feelings of intoxication, heart rate, or THC levels in the blood, suggesting that the combination primarily impacts performance rather than subjective experiences.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Interaction between marihuana and ethanol: effects on psychomotor performance. Perez-Reyes, M., Hicks, RE., Bumberry, J., et al.[2019]

The study of 589 drivers showed that while blood THC concentration is related to specific physical signs like conjunctival injection and pupil dilation, it does not correlate with most clinical tests for impairment.

When THC and ethanol are present together, the risk of being judged impaired significantly increases, indicating that their combined effects on driving ability are greater than either substance alone.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Impairment due to cannabis and ethanol: clinical signs and additive effects. Bramness, JG., Khiabani, HZ., Mørland, J.[2019]

Vaporizing cannabis significantly increases blood levels of THC and its active metabolite 11-OH-THC, especially when combined with low-dose alcohol, which may lead to greater impairment in driving performance.

In a study of 32 adult cannabis smokers, those who consumed alcohol before vaporizing cannabis showed higher maximum blood concentrations of THC, suggesting that the combination of these substances could enhance impairment and should be carefully considered in driving-related regulations.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Controlled Cannabis Vaporizer Administration: Blood and Plasma Cannabinoids with and without Alcohol. Hartman, RL., Brown, TL., Milavetz, G., et al.[2019]

This study will assess the effects of both oral and vaporized cannabis on driving performance, cognitive abilities, and field sobriety in healthy adults, involving 64 participants across two double-blind, placebo-controlled trials.

By examining the impact of cannabis alone and in combination with alcohol, the research aims to enhance understanding of impairment levels, which could influence public policy and law enforcement standards regarding cannabis and alcohol use.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effects of oral and vaporized cannabis alone, and in combination with alcohol, on driving performance using the STISIM driving simulator: A two-part, double-blind, double-dummy, placebo-controlled, randomized crossover clinical laboratory protocol. Zamarripa, CA., Novak, MD., Weerts, EM., et al.[2023]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC6500580/

Trends and correlates of driving under the influence ... This study demonstrated different time trends of DUIA by substance use type. From 2008 to 2014, DUIA prevalence decreased significantly in all substance use ...

2. sciencedirect.com sciencedirect.com/science/article/pii/S2665910725000234

Alcohol and drug detection rates in road traffic Driving under the influence of alcohol or drugs is a significant contributing factor to road traffic crashes. Detection rates for alcohol ...

3. cdc.gov cdc.gov/mmwr/preview/mmwrhtml/mm6448a1.htm

Driving Under the Influence of Alcohol, Marijuana, and ... During 2002–2014, the prevalence of driving under the influence of alcohol alone significantly declined by 59% among persons aged 16–20 years ( ...

4. researchgate.net researchgate.net/publication/275506162_Probability_of_arrest_while_driving_under_the_influence_of_alcohol

Probability of arrest while driving under the influence ... The probability of arrest while driving at a blood alcohol level over 0.10% was 0.0058 (about one in 200).

5. nhtsa.gov nhtsa.gov/sites/nhtsa.gov/files/documents/812355_drugalcoholcrashrisk.pdf

Drug and Alcohol Crash Risk: A Case-Control Study This study used a “case-control” design to estimate the risk of crashes involving drivers using drugs, alcohol or both. Data was collected in Virginia Beach, ...

6. cdc.gov cdc.gov/cannabis/health-effects/driving.html

Cannabis and Driving If you intend to drive, the safest option is not to use any alcohol or drugs, including cannabis. Here are steps you can take to help prevent ...

7. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10703156/

Can inhaled cannabis users accurately evaluate impaired ... A recent study performed without blood THC levels found that 50% of young occasional cannabis users thought their driving was unaffected after ...

8. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC2722956/

THE EFFECT OF CANNABIS COMPARED WITH ... The Swedish study also found that, of the 291 DUI arrestees who were positive for both THC and alcohol, the average THC blood level was only 2.3 ng/mL, again ...

9. nhtsa.gov nhtsa.gov/sites/nhtsa.gov/files/documents/812440-marijuana-impaired-driving-report-to-congress.pdf

Marijuana-Impaired Driving – A Report to Congress The report describes the absorption, distribution and elimination of delta-9-tetrahydrocannabinal (THC) the primary psychoactive substance in marijuana, ...

10. sciencedirect.com sciencedirect.com/science/article/abs/pii/S0001457523004232

Predicting changes in driving performance in individuals ... A recent study of individuals transported to Level-1 trauma centers following motor vehicle crashes showed that 55.8 % tested positive for drugs, including ...