Effects of Inhaled Cannabis on Driving Performance

April 30, 2018 updated by: Gary R Gaffney

The purpose of this study is to expand understanding of the effects of cannabis on driving performance with and without the presence of low levels of alcohol.

This project will involve the development a of a protocol and driving environment that is sensitive to the effects of cannabis on driving performance by building on prior driving situations used previously for testing the effects of alcohol on driving.

Study Overview

Detailed Description

Individuals will be recruited who are currently users of cannabis and alcohol to participate in this study. They will undergo a physical exam at screening. There will be six study visits where the subject will arrive at the Clinical Research Unit(University of Iowa Hospitals & Clinics) the night before dosing. At each visit subjects will be receive one of the following six dosing regimens: placebo alcohol with placebo cannabis; placebo alcohol with low-dose cannabis, placebo alcohol with higher-dose of cannabis, low dose alcohol with placebo cannabis; low dose alcohol with low dose cannabis, low dose alcohol with higher-dose of cannabis. After dosing, participants will have provide saliva samples and blood drawn periodically to check cannabis levels and will complete a driving simulation. After completing the drive, additional saliva samples and blood draws will occur and participants will be monitored until it is safe to transport home.

Study Type

Interventional

Enrollment (Actual)

98

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • Iowa
      • Iowa City, Iowa, United States, 52242
        • National Advanced Driving Simulator

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

21 years to 55 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Healthy adult (age 21-55) men and women, based on medical and psychological evaluation
  • Currently valid unrestricted (except for vision correction) US driver's license
  • Licensed driver for at least the past two years
  • Drove at least 1300 miles in the past year, by self-report
  • Live within an 80 mile radius of NADS
  • Available for an overnight stay followed by a full-day study session for six sessions
  • Must be considered a light or moderate drinker according to Quantity-Frequency-Variability Scale (QFV)
  • Cannabis use with a minimum frequency averaging at least one day per quarter and no more than three days a week during the three months prior to study entry
  • Peripheral veins suitable for repeated venipuncture and/or placement of an intravenous catheter
  • Systolic blood pressure within a clinically normal range (120 ± 30 mmHg) and -diastolic blood pressure of 80 ± 20 mmHg..
  • Good command of written and spoken English
  • Female subjects with reproductive potential must agree to use (and/or have their partner use) one (1) acceptable method of birth control beginning at the screening visit throughout the study (including intervals between treatment periods/panels) and until 2 weeks after the last dose of study drug in the last treatment period. Acceptable methods of birth control include the following: intrauterine device (IUD-with or without local hormone release), diaphragm, spermicides, cervical cap, contraceptive sponge, oral contraceptives or condoms. Abstinence is an alternative lifestyle and subjects practicing abstinence may be included in the study.

Exclusion Criteria:

  • Presence of any clinically significant illness, as detected by history, physical examination, and/or laboratory tests, that might influence driving performance (e.g., seizures, sleep apnea, narcolepsy, vertigo, chronic fatigue syndrome) or put the subject at increased risk of adverse events (e.g., cardiac arrhythmia, hypertension)
  • History of a clinically significant adverse event associated with cannabis or alcohol intoxication
  • Donation of more than 450 mL of blood within 14 days of study drug administration
  • If female, pregnant or nursing
  • Currently interested in or participating in drug abuse treatment, or participated in drug abuse treatment within 60 days preceding study enrollment
  • Currently taking drugs that are contraindicated for use with study drugs
  • Requires any special equipment to aid in driving (ex. pedal extensions, hand brake or throttle, spinner wheel knobs or other non-standard equipment)
  • Significant history of motion sickness or demonstrates significant simulator sickness during practice drives at screening (SSQ). Subjects must have scores below the following values on the SSQ: Nausea < 21, Oculomotor <32, Disorientation < 15, and Total Score < 32.
  • Current alcohol or cannabis use disorder, as identified by the Alcohol Use Disorders Identification Test for alcohol or Cannabis Use Disorders Identification Test for cannabis.
  • History of any illness that, in the opinion of the study investigator, might confound the results of the study or pose an additional risk to the subject from study participation
  • Prior participation in a driver impairment or distraction-related research study conducted at NADS that uses the same base drive.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: 0% THC with 0.065 g/dL BAC
Subjects will be dosed to an approximate peak BAC of 0.065%. Subjects will be tested on the decline such that subjects will be at or above the goal BAC (0.05%) throughout the drive
Other Names:
  • Ethanol
  • Ethyl Alcohol
Cannabis vapor is produced from 500 mg either placebo (0% THC), approximately 2.5-3.5% THC (low dose), or approximately 6.0-7.5% THC (high dose) bulk cannabis plant material to yield doses of approximately 0, 12.5-17.5, or 30-37.5 mg THC
Other Names:
  • Marijuana
  • Marihuana
Experimental: 2.5-3.5% THC with 0.065 g/dL BAC
Subjects will be dosed to an approximate peak BAC of 0.065%. Subjects will be tested on the decline such that subjects will be at or above the goal BAC (0.05%) throughout the drive
Other Names:
  • Ethanol
  • Ethyl Alcohol
Cannabis vapor is produced from 500 mg either placebo (0% THC), approximately 2.5-3.5% THC (low dose), or approximately 6.0-7.5% THC (high dose) bulk cannabis plant material to yield doses of approximately 0, 12.5-17.5, or 30-37.5 mg THC
Other Names:
  • Marijuana
  • Marihuana
Experimental: 6.0-7.5% THC and 0.065 g/dL BAC
Subjects will be dosed to an approximate peak BAC of 0.065%. Subjects will be tested on the decline such that subjects will be at or above the goal BAC (0.05%) throughout the drive
Other Names:
  • Ethanol
  • Ethyl Alcohol
Cannabis vapor is produced from 500 mg either placebo (0% THC), approximately 2.5-3.5% THC (low dose), or approximately 6.0-7.5% THC (high dose) bulk cannabis plant material to yield doses of approximately 0, 12.5-17.5, or 30-37.5 mg THC
Other Names:
  • Marijuana
  • Marihuana
Experimental: 2.5-3.5% THC with 0 g/dL BAC
Subjects will be dosed to an approximate peak BAC of 0.065%. Subjects will be tested on the decline such that subjects will be at or above the goal BAC (0.05%) throughout the drive
Other Names:
  • Ethanol
  • Ethyl Alcohol
Cannabis vapor is produced from 500 mg either placebo (0% THC), approximately 2.5-3.5% THC (low dose), or approximately 6.0-7.5% THC (high dose) bulk cannabis plant material to yield doses of approximately 0, 12.5-17.5, or 30-37.5 mg THC
Other Names:
  • Marijuana
  • Marihuana
Experimental: 6.0-7.5% THC with 0 g/dL BAC
Subjects will be dosed to an approximate peak BAC of 0.065%. Subjects will be tested on the decline such that subjects will be at or above the goal BAC (0.05%) throughout the drive
Other Names:
  • Ethanol
  • Ethyl Alcohol
Cannabis vapor is produced from 500 mg either placebo (0% THC), approximately 2.5-3.5% THC (low dose), or approximately 6.0-7.5% THC (high dose) bulk cannabis plant material to yield doses of approximately 0, 12.5-17.5, or 30-37.5 mg THC
Other Names:
  • Marijuana
  • Marihuana
Experimental: 0% THC with 0 g/dL BAC
Subjects will be dosed to an approximate peak BAC of 0.065%. Subjects will be tested on the decline such that subjects will be at or above the goal BAC (0.05%) throughout the drive
Other Names:
  • Ethanol
  • Ethyl Alcohol
Cannabis vapor is produced from 500 mg either placebo (0% THC), approximately 2.5-3.5% THC (low dose), or approximately 6.0-7.5% THC (high dose) bulk cannabis plant material to yield doses of approximately 0, 12.5-17.5, or 30-37.5 mg THC
Other Names:
  • Marijuana
  • Marihuana

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Driving Performance
Time Frame: Through entire drive, 0.5-1.3 hr post cannabis administration.
Measured by standard deviation of lane position. Metrics of driving performance were modeled using the SAS GLM Select function to identify changes in driver performance. Numbers represents coefficients on the regression equation such that this increase would be expected for every unit increase. A unit for THC is 1 ng/ml and a unit for BAC is 0.01% BAC. In understanding the regression coefficients, for THC the units for the coefficient would be expressed as cm per (ng/ml of THC), and for BrAC the units for the coefficient would be expressed as cm per (0.01% BrAC). The overall regression equation would be represented as SDLP = Intercept + Cthc x THC + Cbrac x BrAC. The coefficients indicate the strength of the effect on driving performance with higher coefficients indicating larger effects relative to the concentrations. Coefficients of zero indicate no effect or interactive effect.
Through entire drive, 0.5-1.3 hr post cannabis administration.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
THC Concentration in Plasma Sample
Time Frame: -0.7 hr, 0.25hr, 1.1 hr, 2 hr, 3 hr, 4.5 hr, 6 hr, 8 hr post cannabis administration
Measurement of THC concentration levels in plasma over the course of each visit compared to that of the other visits.
-0.7 hr, 0.25hr, 1.1 hr, 2 hr, 3 hr, 4.5 hr, 6 hr, 8 hr post cannabis administration
THC Concentration Levels in Whole Blood
Time Frame: -0.7 hr, 0.25hr, 1.1 hr, 2 hr, 3 hr, 4.5 hr, 6 hr, 8 hr post cannabis
Measurement of THC concentration levels in whole blood over the course of each visit compared to that of the other visits.
-0.7 hr, 0.25hr, 1.1 hr, 2 hr, 3 hr, 4.5 hr, 6 hr, 8 hr post cannabis

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Investigators

  • Principal Investigator: Gary G Gaffney, M.D., National Advanced Driving Simulator

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

July 1, 2012

Primary Completion (Actual)

March 1, 2014

Study Completion (Actual)

March 1, 2014

Study Registration Dates

First Submitted

June 4, 2012

First Submitted That Met QC Criteria

June 14, 2012

First Posted (Estimate)

June 15, 2012

Study Record Updates

Last Update Posted (Actual)

May 2, 2018

Last Update Submitted That Met QC Criteria

April 30, 2018

Last Verified

April 1, 2018

More Information

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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