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

40 Participants Needed

Trial Summary

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.

What data supports the effectiveness of the drug combination of inhaled delta-9-THC and oral ethanol for DUI effects?

Research shows that using cannabis (which contains THC) with alcohol can alter how the body processes these substances, potentially affecting their impact on driving. One study found that cannabis can reduce the peak levels of alcohol in the blood, which might change how both substances affect driving performance. ^{1 2 3 4 5}

Is the combination of alcohol and THC generally safe for humans?

Research shows that using alcohol and THC together can significantly impair driving and psychomotor skills, which are necessary for tasks like driving. The combination can have additive or even synergistic effects, meaning the impairment can be greater than using either substance alone, especially in people who are not regular cannabis users. ^{2 3 6 7 8}

How does the drug combination of inhaled THC and oral ethanol differ from other treatments for DUI effects?

This drug combination is unique because it involves both inhaled THC and oral ethanol, which together can have complex interactions affecting cognitive and motor functions. Unlike other treatments, this combination can lead to additive or even synergistic effects, potentially enhancing impairment more than either substance alone. ^{6 7 8 9 10}

What is the purpose of this trial?

The overarching goal of this study is to characterize the effects of ethanol and cannabinoids on simulated driving and related cognition.

Eligibility Criteria

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

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

Treatment Details

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.

Participant Groups

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+

Findings from Research

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]

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]

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]

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]

References

1. Germany pubmed.ncbi.nlm.nih.gov

Influence of ethanol on cannabinoid pharmacokinetic parameters in chronic users. [2016]

2. Switzerland 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. [2023]

3. England pubmed.ncbi.nlm.nih.gov

Controlled Cannabis Vaporizer Administration: Blood and Plasma Cannabinoids with and without Alcohol. [2019]

4. England pubmed.ncbi.nlm.nih.gov

Marihuana attenuates the rise in plasma ethanol levels in human subjects. [2015]

5. Ireland pubmed.ncbi.nlm.nih.gov

Physiochemical and pharmacological characterization of a Delta(9)-THC aerosol generated by a metered dose inhaler. [2019]

6. England pubmed.ncbi.nlm.nih.gov

Impairment due to cannabis and ethanol: clinical signs and additive effects. [2019]

7. Germany pubmed.ncbi.nlm.nih.gov

Divided attention performance of cannabis users and non-users following cannabis and alcohol. [2020]

8. England pubmed.ncbi.nlm.nih.gov

Interaction between marihuana and ethanol: effects on psychomotor performance. [2019]

9. Australia pubmed.ncbi.nlm.nih.gov

Ethanol and delta9-tetrahydrocannabinol interactive effects on human perceptual, cognitive and motor functions. II. [2013]

10. Australia pubmed.ncbi.nlm.nih.gov

The interaction of ethanol and delta9-tetrahydrocannabinol in man: effects on perceptual, cognitive and motor functions. [2013]