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Using a Field Performance Test on an iPad to Evaluate Driving Under the Influence of Cannabis

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ClinicalTrials.gov Identifier: NCT02849587
Recruitment Status : Recruiting
First Posted : July 29, 2016
Last Update Posted : May 3, 2018
Sponsor:
Information provided by (Responsible Party):
Barth Wilsey MD, University of California, San Diego

Brief Summary:
This study was authorized by the California Legislature (Assembly Bill 266, the Medical Marijuana Regulation and Safety Act (73) to help with detection of driving under the influence of cannabis. One hundred and eighty healthy volunteers will inhale smoked cannabis with either 0% (placebo), 5.9%, or 13.4% Δ9-THC at the beginning of the day, and then complete driving simulations, iPad-based performance assessments, and bodily fluid draws (e.g., blood, saliva, breath) before the cannabis smoking and a number of times over the subsequent 6 hours after cannabis smoking. The purpose is to determine (1) the relationship of the dose of Δ9-THC on driving performance and (2) the duration of driving impairment in terms of hours from initial use, (3) if saliva or expired air can serve as a useful substitute for blood sampling of Δ9-THC in judicial hearings and (4) if testing using an iPad can serve as a useful adjunct to the standardized field sobriety test in identifying acute impairment from cannabis.

Condition or disease Intervention/treatment Phase
Cannabis Intoxication Drug: cannabis Not Applicable

Detailed Description:

There are several studies that suggest higher doses of whole-blood Δ9-THC concentration are associated with increased crash risk and crash culpability. However, attempts to define a cut-off point for blood Δ9-THC levels have proven to be challenging. Unlike alcohol, for which a level can be reasonably measured using a breathalyzer (and confirmed with a blood test), detection of a cut-off point for intoxication related to Δ9-THC concentration has eluded scientific verification. Recent evidence suggests blood Δ9-THC concentrations of 2-5 ng/mL are associated with substantial driving impairment, particularly in occasional smokers. Others have countered that this level leads to false positives, particularly in heavy cannabis users inasmuch as THC may be detectable in their blood specimens for 12-24 hours after inhalation. Given that 12 to 24 hours is well beyond the likely period of driving impairment, this would appear to be a justifiable objection to a per se cut-off point for a Δ9-THC concentration indicative of impairment. Maximal driving impairment is found 20 to 40 minutes after smoking, and the risk of driving impairment decreases significantly after 2.5 hours, at least in those who smoke 18 mg Δ9-THC or less, the dose often used experimentally to duplicate a single joint. Other studies, however, report residual MVA crash risk when cannabis is used within 4 hours prior to driving.

The roadside examination using the Standardized Field Sobriety Test (SFST) for proof of cannabis-related impairment has not been an ideal alternative to blood levels. Originally devised to evaluate impairment under the influence of alcohol, the SFST is comprised of three examinations administered in a standardized manner by law enforcement officers. The 'Horizontal Gaze Nystagmus' (HGN), the 'One Leg Stand' (OLS) and the 'Walk and Turn' test (WAT) require a person to follow instructions and perform motor activities. During the assessments, officers observe and record signs of impairment. In one study, Δ9-THC produced impairments on overall SFST performance in only 50 % of the participants. In a separate study involving acute administration of cannabis, only 30% of people failed the SFST. This discrepancy in rate of failure was thought to be in part due to the participant's cannabis use history. The reported frequency of cannabis use varied from once a week to once every 2-6 months in the study where there was a failure on the SFST by 50% of the participants. The other study included more frequent users who smoked cannabis on at least four occasions per week.

Based upon the above, another means is needed to help law enforcement officers discern driving under the influence of cannabis. One future possibility is the development of performance-based measures of cannabis-related impairments. This will include testing of critical tracking, time estimation, balance and visual spatial memory learning. The investigators have selected brief measures in order to be practicably administered repeatedly over a short time period, as well as tests that have the potential to translate to a tablet-based format, should there be benefit in possibly including these in future performance-based measures for use in the field by law enforcement officers (e.g., a cannabis-focused field sobriety test).


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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 180 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Screening
Official Title: A Randomized, Controlled Trial of Cannabis in Healthy Volunteers Evaluating Simulated Driving, Field Performance Tests and Cannabinoid Levels
Study Start Date : January 2017
Estimated Primary Completion Date : June 2019
Estimated Study Completion Date : June 2019

Resource links provided by the National Library of Medicine


Arm Intervention/treatment
Placebo Comparator: Placebo Cannabis
Subjects will receive cannabis with placebo THC
Drug: cannabis
Participants will smoke a cannabis cigarette ad libitum as per their usual routine
Other Name: marijuana

Experimental: Cannabis with 5.9% THC
Subjects will receive cannabis with 5.9% THC
Drug: cannabis
Participants will smoke a cannabis cigarette ad libitum as per their usual routine
Other Name: marijuana

Experimental: Cannabis with 13.4% THC
Subjects will receive cannabis with 13.4% THC
Drug: cannabis
Participants will smoke a cannabis cigarette ad libitum as per their usual routine
Other Name: marijuana




Primary Outcome Measures :
  1. Driving Simulation Global Driving Deficit Score (GDDS) [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The GDDS is comprised of key variables from the simulator tasks (e.g., crashes, running a red light and perception response time for the amber light dilemma, SDLP, SuRT accuracy, time to collision on the gap acceptance task, failure on the audio direction task).


Secondary Outcome Measures :
  1. Driving Simulation Measuring Deviation of Lateral Position [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    Driving simulation measuring standard deviation of lateral position (in feet) during the SuRT task

  2. Driving Simulation Measuring Speed Deviation [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    Participants will be instructed to maintain their speed during the SuRT task. The primary outcome is speed deviation in miles per hour.

  3. Driving Simulation Measuring Divided Attention [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    Participants will be instructed to respond to divided attention stimuli in the SuRT task. The primary outcomes are number correct and response latency.

  4. Driving Simulation Measuring Car Following - Coherence [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The outcome is coherence between the participant and lead cars (a general correlation [0-1] of the participant's ability to accurately track the speed variations of the lead car).

  5. 5. Driving Simulation Measuring Car Following - reaction time to changes in the lead car's speed. [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The outcome is time delay in seconds (response time to changes in the lead car's speed).

  6. Driving Simulation Measuring Car Following - distance from the lead car. [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The outcome is distance (number of feet) from the lead car.

  7. Driving Simulation Measuring Crash avoidance response time (in milliseconds) [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    In order to assess treatment effects during routine and non-routine events the investigator will include scenarios addressing crash avoidance (e.g., object entering the roadway).

  8. Driving Simulation Measuring Yellow Light Dilemma [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    Stopping accuracy and perception response time will be measured after the traffic light turns yellow.

  9. Driving Simulation Left Turn Gap Acceptance [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The time to collision with on-coming vehicles will be assessed.

  10. Performance-based tablet assessment: Critical Tracking [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The participant will follow a moving target (square) with her/his finger.

  11. Performance-based tablet assessment: Time estimation [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The research associate will administer a brief measure of time estimation with randomly generated durations.

  12. Performance-based tablet assessment: Balance [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    To assess balance, participants will perform a Modified Romberg Test, without the time estimation component. Circular, forward-backward, and lateral postural sway will be assessed via an accelerometer.

  13. Performance-based tablet assessment: Visual Spatial Learning Test [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    Short term memory will be tested using a visual-spatial learning test.

  14. Identification of Recent Cannabis Intake Using Whole Blood [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    It has been hypothesized that several cannabinoids (e.g., THC-glucuronide, cannabidiol and cannabinol) might be useful for estimating the last time of cannabis intake The outcome will be the concentration of each cannabinoid expressed in nanograms per milliliter.

  15. Assays for Oral Fluid Cannabidiol [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The levels of cannabidiol in the oral fluid samples will be determined in nanograms per milliliter.

  16. Assays for Oral Fluid Cannabinol [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The levels of cannabinol in the oral fluid samples will be determined in nanograms per milliliter.

  17. Assays for Oral Fluid THC-glucuronide [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The levels of THC-glucuronide in the oral fluid samples will be determined in nanograms per milliliter.

  18. Assays of THC in Breath Specimens [ Time Frame: participants will be followed for the duration of an 7 hour, single day human laboratory experiment, and the outcome will be measured once before they receive study medication and then 4 additional times during the treatment day ]
    The THC will be measured in picograms per ml.



Information from the National Library of Medicine

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Ages Eligible for Study:   21 Years to 55 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Be a licensed driver.
  • Need to have acuity of 20/40 or better, with or without correction on a Snellen Visual Acuity eye chart.

Exclusion Criteria:

  • At the discretion of the examining physician, individuals with significant cardiovascular, hepatic or renal disease, uncontrolled hypertension, and chronic pulmonary disease (eg, asthma, COPD) will be excluded.
  • Unwillingness to abstain from cannabis for 2 days prior to screening and experimental visits
  • Positive pregnancy test
  • A positive result on toxicity screening for cocaine, amphetamines, opiates, and phencyclidine (PCP) will exclude individuals from participation.
  • Unwilling to refrain from driving or operating heavy machinery for four hours after consuming study medication.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02849587


Contacts
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Contact: Thomas Marcotte, PhD tmarcotte@ucsd.edu

Locations
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United States, California
UC Center for Medicinal Cannabis Research, UC San Diego Recruiting
San Diego, California, United States, 92103
Contact: Thomas Marcotte, PhD         
Contact       tmarcotte@ucsd.edu   
Principal Investigator: Thomas Marcotte, PhD         
Sub-Investigator: Barth Wilsey, MD         
Sponsors and Collaborators
University of California, San Diego
Investigators
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Principal Investigator: Thomas Marcotte, PhD University of California, San Diego

Additional Information:
Publications:

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Responsible Party: Barth Wilsey MD, Associate Physician, University of California, San Diego
ClinicalTrials.gov Identifier: NCT02849587     History of Changes
Other Study ID Numbers: 160641
First Posted: July 29, 2016    Key Record Dates
Last Update Posted: May 3, 2018
Last Verified: May 2018
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Undecided
Keywords provided by Barth Wilsey MD, University of California, San Diego:
Driving Under the Influence
Memory Impairment
Reaction Time
Time Perception
Additional relevant MeSH terms:
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Marijuana Abuse
Substance-Related Disorders
Chemically-Induced Disorders
Mental Disorders