By Nancy Qiao
On October 17th 2018, the Cannabis Act came into effect, giving millions of Canadians access to cannabis. The legalization of cannabis presents multiple new challenges to the Canadian healthcare system. Prior to October 17th 2018, patients could access cannabis for medical purposes with a medical document from an authorized prescriber. However, an increasing number of patients are accessing cannabis without medical authorization and the number of patients with medical authorization has plateaued since legalization. Not only is more research needed to better understand the physiological effects of medical cannabis but also new guidelines should be developed for cannabis management in patients admitted to hospital.
Cannabis comes from the cannabis sativa plant that originated in Asia. It can be used by many different routes, including smoking/vaping, oral/sublingual, and transdermal. Typically, inhalation has the fastest onset of action but shortest duration of effect, whereas oral administration has a slower onset but longer duration of action. Regardless of the form of use, the therapeutic and psychoactive effects of cannabis come from a class of substances known as cannabinoids. The two most common cannabinoids are tetrahydrocannabinol (THC) and cannabidiol (CBD). Of these substances, tetrahydrocannabinol (THC) contributes mainly to the “high” associated with cannabis use. In particular, THC achieves these effects by binding to the cannabinoid type 1 receptor of the peripheral and central nervous system.
The precise effects of these cannabinoids are still unclear, and no official Health Canada indication is currently available. However, there is moderate evidence for indications such as spasticity and muscle spasm due to multiple sclerosis, paraplegia, nausea and vomiting due to chemotherapy, chronic pain, and sleep disorders. Weaker evidence suggests that patients with an anxiety disorder, cancer related pain, and fibromyalgia can also benefit from cannabis use.
On the other hand, there are a number of side effects associated with cannabis consumption. These include drowsiness, impaired memory and attention span, disorientation and confusion, impaired motor skills, and irritation. The possibility of these side effects mean that cannabis should be used with caution in certain populations such as pediatric patients, patients having a history of hypersensitivity to cannabinoid products, those with severe cardiovascular disease, those with respiratory disease, patients with severe liver or kidney disease and those with a history of psychiatric disorders, history of substance abuse, and pregnancy/breastfeeding (2).
A 2019 Health Canada survey showed that 24.6% of Canadians had used cannabis in the 12 months prior to the study. However, only 3.8% of the respondents used cannabis for medical purposes with proper medical documentation while 10.5% used cannabis for medical purposes without proper documentation. With the increasing number of patients using cannabis without a medical document, healthcare providers need to answer the difficult question of whether to continue a patient’s cannabis for medical purposes on admission to hospital if the patient had been using cannabis without documentation at home. Beyond the problem of proper documentation, healthcare professionals must also decide on the proper management of patients who are inhaling their cannabis at home as this is prohibited on hospital property due to provincial laws.
Currently, many hospitals do not have policies that outline procedures in these circumstances and many prohibit cannabis without proper medical documentation. As a result, the Canadian Society of Hospital Pharmacists (CSHP) formed a Cannabis Task Force to create a position statement and a best practice document. The Task Force has considered issues such as supply, strategies for patients who smoke/vape, administration, storage, education, clinical competency, and ethical considerations. CSHP encourages pharmacists to incorporate the assessment of cannabis as part of routine patient care. Pharmacists should maintain clinical competency to make decisions related to cannabis use. When approaching patients about their cannabis use, pharmacy professionals must be mindful of their own professional, ethical and moral positions regarding cannabis. Keeping any existing bias in mind, pharmacy professionals must always be objective and non-judgmental towards patients’ cannabis use. Cannabis remains a controversial topic but CHSP is working to assist hospital pharmacists in tackling this difficult clinical issue.
Nancy Qiao is a Pharmacy Student at University of Toronto’s Leslie Dan Faculty of Pharmacy.
