None listed
Conditions
Brief summary
Following the recent decision made by the Australian Commonwealth government to enable the cultivation of cannabis crops for medicinal grade products, it is likely that medicinal cannabis products – plant matter or extracts – will become more available in Australia in the years to follow. Various states including NSW are also investing in clinical trials of cannabinoid medicines for a number of debilitating illnesses, including the use of vaporised leaf cannabis products containing THC (http://www.health.nsw.gov.au/cannabis/Pages/terminal-illness.aspx). In will therefore become increasingly relevant, from a road safety and medico-legal perspective, to better understand the effects of these medicines on driving. The psychoactive constituent of cannabis, THC, is only one of over 100 phytocannabinoids present in the Cannabis Sativa plant that may be promising therapeutic targets in medicine. CBD, for example, is a non-psychoactive cannabinoid with anti-inflammatory, neuroprotective antioxidant, anticonvulsive and antipsychotic properties. Preliminary studies suggest that in animal models CBD also modulates the pharmacological action of THC, dampening its psychotomimetic properties. The presence of phytocannabinoids other than THC (such as CBD) in some medicinal grade cannabinoid products distinguishes them from Australian street grade illicit cannabis, which contains very little to nil CBD. The presence of CBD could have important implications for the effects of cannabis-based medicines on driving. Although other medicines such as benzodiazepines, opioids, and some antidepressants have been shown to impair driving ability, NSW law permits a person who is taking these medicines to drive so long as the drivers’ mental or physical faculties are not affected [9]. The current legal framework for driving under the influence of cannabis (where it is a criminal offence to be driving if THC is detected in saliva – with no functional assessment) reflects the illegal status of cannabis and predates the emergence of medicinal cannabinoid preparations. The premise of the current proposal is to test the effects of a variety of medicinal cannabinoid preparations that differ in their concentrations of the cannabinoids THC and CBD. It is hypothesised that the impairing effects of THC will be modulated and possibly negated by the presence of CBD in medical grade cannabis. This study also seeks to test the efficacy of roadside testing equipment in discerning impaired from non-impaired driving. To establish if there are methods other than saliva testing that can predict driving impairment, this study will utilise an eye-tracking task, subjective measures and cognitive testing procedures.
Interventions
The study is a randomized, crossover, double blind trial comparing the effects of .125g inhaled vaporized cannabis containing various concentrations of tetrahydrocannabinol (THC) and cannabidiol (CBD) on driving performance. Participants will complete 3 sessions, seperated by a washout period of 7 days. Participants will receive one of three varieties of cannabis per session, in a randomised and counter-balanced order. Cannabis types will include cannabis containing either: (a) high THC/low CBD
The study is a randomized, crossover, double blind trial comparing the effects of .125g inhaled vaporized cannabis containing various concentrations of tetrahydrocannabinol (THC) and cannabidiol (CBD) on driving performance. Participants will complete 3 sessions, seperated by a washout period of 7 days. Participants will receive one of three varieties of cannabis per session, in a randomised and counter-balanced order. Cannabis types will include cannabis containing either: (a) high THC/low CBD (11% THC / <1% CBD), (b) high THC/high CBD (11% THC / 11% CBD) or (c) placebo. Study medications will be administered using a Volcano Medic vaporiser under the supervision of study staff.. To assess driving ability, participants will complete a 45-minute advanced driving simulation, beginning 15 minutes after drug administration. Participants will additionally complete a series of cognitive tests designed to measure reaction time. attentional processing and executive function. Biological samples (urine, blood and saliva) will be taken before and at a series of time points following drug administration. These will later be analysed for THC, CBD and endocannabinoids.
Sponsors
The University of Sydney
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
(a) At least 18 years of age, and no more than 50 years of age (b) Prior experience with cannabis (>10 lifetime exposures, <2x/week in previous 2 months) (c) In possession of full Australian drivers license for at least 1 year (d) Proficiency in English, and willing and capable of providing informed consent to the study procedures
Exclusion criteria
(a) Any clinically significant prior adverse response to cannabis, cannabinoid products or synthetic cannabinoids, as assessed by an Addiction Medicine specialist (e.g. panic or other anxiety attacks, arrhythmia, falls, seizures) (b) Cannabis dependence (ICD-10 criteria) (c) A desire to abstain from cannabis use (d) Past year mood or anxiety disorder (DSM-V criteria) (e) Lifetime manic episode or psychotic illness (DSM-V criteria), or suspected family history of schizophrenia (f) Interest in treatment for cannabis use (g) Hypertension, cardiovascular disease, chronic pulmonary disease or asthma (h) Under 18 years of age or over 50 years of age (i) Use of medications that may impact upon the metabolism and excretion of cannabinoids (e.g. CYP450 enyzme inducers/inhibitors), or may impact upon driving ability (e.g. mood stabilisers, sedatives); and (j) Pregnancy (primary plasma hCG screen in women of child bearing potential, confirmed with blood test if urine test positive) and women of child bearing potential must agree to using a reliable form of contraception during and one month after completion of the project. (k) Required to complete drug testing for cannabis (e.g. workplace testing; court order)
Outcome results
None listed