The effect of two concentrations of delta-9 tetrahydrocannabinol (THC, the active ingredient in Cannabis) on saliva-based drug detection systems and driving performance

Over the three week experimental period, participation will receive all of the experimental doses. One dose will be taken at each session (i.e. high, low THC or placebo) and the order of dosing will be randomised. 1. THC (high dose), comprising 20mg/kg of THC (0.092mg THC per 5ml dose) in 5 ml bearer oil. 2. THC (low dose), comprising 10mg/kg of THC (0.046mg THC per 5ml dose) in 5 ml bearer oil. Each dose is complete and is not weight related, i.e. participants will not have repeated doses .of the THC oil. The dose will be administered orally in the form of a 5ml bearer sesame oil, to be delivered in an unmarked amber coloured vial. Adherence to the treatment protocol will be confirmed by assessing an empty treatment vial, which will be returned to the research nurse. The dose (high, low THC or placebo) will be randomised and will be provided once to participants at baseline at each of the three testing sessions (to occur one week apart). The saliva tests employed are the same as those currently used in Policing practice during random roadside drug tests; The Securetec Drugwipe (registered trademark) TWIN oral drug test. Saliva will be obtained using Securetec Drugwipe (registered trademark) TWIN and will be taken at six time points during each experimental session. The Securetec Drugwipe (registered trademark) TWIN drug screen requires an absorbent pad to be placed over the tongue for approximately 20 seconds. 1ml of saliva will be taken per sample, therefore approximately 6ml in total over each of the three experimental sessions. A sample volume of less than 10 micro litres is sufficient for analysis. The device is wiped on the tongue, when the colour has changed from pink to yellow there is the required amount of saliva to obtain the results. The first saliva sample will be used to test for the presence of drugs (baseline sample), and the other samples will be used to test for the concentration of the treatment (or placebo) over time as part of the testing session. Saliva testing will occur at baseline (prior to dosing), immediately post dosing (5 minutes post dosing), 30 minutes post dosing, 1 hour post dosing, 3 ours post dosing and at 4 hours post dosing. Driving performance will be assessed using the Forum 8 driving simulator, and driving performance will be assessed three times each study session. The simulator consists of a car unit with adjustable car seats and a dashboard and includes a steering wheel, turn sign indicators, gear lever, brake and accelerator pedals for vehicle control. The system generates realistic roadway scenery which is presented on three integrated TV screens 1.90 meters in front of the centre of the steering wheel. The speed and gear number are displayed on the dashboard and screen. Auditory feedback is provided by speakers and included the sound of the engine, braking, speeding in curves, and driving off-road. Driving assessment will take place at baseline (prior to dosing), and at 30 minutes and at 3 hours post dosing.