New guidance on driving and medicinal cannabis

In Australia, it is an offence for a person to drive when impaired by a substance, including any detectable amount of THC in their system.
 
But with medicinal cannabis use growing and prescribed for various conditions, and limited guidance for healthcare professionals about patients who drive, how can prescribers ensure these patients understand risk of impairment and road safety rules?
 
A landmark project aims to address this, by developing guidance for healthcare professionals assisting patients prescribed medicinal cannabis with new decision-making resources. 
 
Developed with Road Safety Victoria and an expert committee, a sub-committee of GPs who prescribe medicinal cannabis was then recruited to cross-check the suitability of the guidelines.
 
Associate Professor Vicki Kotsirilos was the GP on the expert committee. With almost 40 years of clinical experience and Australia’s first authorised prescriber of medicinal cannabis, she represents the RACGP on the committee of experts for developing the guidelines.
 
She told newsGP the resources should be helpful for GPs throughout Australia and support all healthcare professionals to have conversations with patients about their driving needs, when considering medicinal cannabis treatment and throughout the treatment process. 
 
‘The information and resources are an excellent guide for conversations with our patients about driving,’ Associate Professor Kotsirilos said.
 
‘The principles of the guidelines are suitable for all GPs to use throughout Australia even though they were developed in Victoria.
 
‘[They] support health professionals when deciding to prescribe medicinal cannabis, and if the patient chooses to drive.’
 
The resources include a decision support tool and ‘driving needs checklist’ for health professionals, as well as a patient factsheet.
 
With a person driving with any detectable amount of THC in their system an offence under Australia’s Presence Law, a valid prescription for medicinal cannabis still cannot be used as a defence against a charge of testing positive for THC on a roadside drug test.
 
Therefore, it is essential for prescribers of medicinal cannabis to have conversations with patients, according to Associate Professor Kotsirilos, with discussions about driving ‘held early in the conversation’ prior to considering treatment, and ensuring patients understand the impacts of THC on their body.
 
‘It is important we educate and well inform our patients about medicinal cannabis and how it impacts their driving,’ she said.
 
‘Impairment generally increases as THC levels increase in the blood and saliva. However, current evidence suggests there’s a weak or inconsistent correlation between levels of THC in blood and levels in saliva and the degree of impairment.
 
‘Some patients can be quite sensitive to even very low levels of THC – the level of THC measured in saliva doesn’t reflect the level in blood.
 
‘Impairment risk and road safety are affected by a number of factors, including fatigue, concomitant use of alcohol, drugs and sedating medication such as analgesia and antihistamines that should also be taken into consideration and monitored when prescribing and dispensing medicinal cannabis.’
 
THC-containing products are contraindicated for commercial vehicle drivers, including heavy vehicle drivers, public passenger vehicle drivers, dangerous goods drivers, and emergency vehicle drivers, and also contraindicated for safety-critical occupational roles, Associate Professor Kotsirilos adds.
 
‘Prescribing THC-containing products is not appropriate if a person is unlikely to be able to comply with advice to abstain from driving due to work, lifestyle, or other factors,’ she said.
 
Associate Professor Kotsirilos also recommends that if a patient chooses to drive, where possible, prescribe cannabidiol (CBD)-only medicines.
 
‘Patients taking CBD-only products can drive unless they feel impaired,’ she said.
 
‘An important consideration for driving is whether the medicinal cannabis product contains THC. Delta-9 THC, or THC, is the main psychoactive component in cannabis.’
 
The RACGP’s declaration form covers risks and side-effects, interactions and avoidance of driving, and Associate Professor Kotsirilos said is valuable for initial discussions with patients prior to commencing medicinal cannabis products that contain THC.
 
‘It is helpful to provide informed consent and for patients to sign a declaration acknowledging their understanding of the advice regarding driving laws and the risk of side effects with THC-containing products,’ she said.

Associate Professor Vicki Kotsirilos says discussions about driving should be held early with patients before considering medicinal cannabis.
 
Associate Professor Kotsirilos says as part of GPs’ role as trusted healthcare advisors, early and ongoing conversations about driving are important to help patients make informed decisions about medicinal cannabis treatment, as well as when they should report their underlying medical condition to the Department of Transport Medical Review.
 
‘Whether a patient is taking medicinal cannabis or any other substances that may impair driving, GPs should encourage patients to report any illness, disability or medical condition that may impact the patient’s ability to drive safely, including any medicines they are taking,’ she said.
 
‘Drivers are required to inform the Medical Review if they have a long-term medical condition, disability, or injury that could affect their fitness to drive.
 
‘Patients trust and rely on the advice of their GP and healthcare practitioners about the impact of their medical conditions and treatments on their driving ability, including when they should report.’
 
All medicinal cannabis resources are available for download via the Transport Victoria website, including:

• driving decision support resource
• driving needs checklist
• driving patient factsheet
• advising patients about road safety laws.

decision making tools driving impairment fitness to drive medicinal cannabis prescribing Road Safety Victoria