Canadian Association of Gastroenterology Position Statement: Use of Cannabis in Gastroenterological and Hepatic Disorders

Medical cannabinoid products are widely used in Canada to treat medical symptoms of all kinds, and gastrointestinal (GI) symptoms are among the most commonly cited reasons for use (1). Cannabis is also widely used recreationally (2), and legalization of recreational use has occurred in Canada. Currently, cannabis is not an approved therapeutic product in Canada. However, health care practitioners may authorize the use of cannabis in various forms or synthetic cannabinoids for the relief of symptoms associated with a variety of disorders which have not responded to conventional medical treatments. These include pain and spasticity due to multiple sclerosis; severe nausea and vomiting related to cancer chemotherapy; loss of appetite and body weight in cancer patients and patients with HIV/AIDS; chronic noncancer pain (mainly neuropathic); severe refractory cancer-associated pain; insomnia and depressed mood associated with chronic diseases (HIV/ AIDS, chronic noncancer pain); and symptoms encountered in the palliative/end-of-life setting (3). Yet, evidence supporting the safety and efficacy of cannabis for the treatment of many of these conditions is often limited and inconsistent. Certainly, a biological rationale exists for cannabinoids to have possible benefit for GI symptoms based on its known physiologic actions (3, 4) but research in the field has been hampered by its historical illegality, plus the inability to patent a natural product which is widely available. However, there are also concerns regarding potential adverse effects of acute and chronic cannabis use including dependence, tolerance, psychiatric disorders, poor school or work performance, nervous system disorders, vascular and cardiac disorders, carcinogenesis and gastrointestinal disorders such as cannabis hyperemesis syndrome (CHS) and fibrosis progression in chronic hepatitis C. The pharmacodynamics and pharmacokinetics of inhaled and ingested cannabis are reasonably well known and are reviewed elsewhere (3). However, very few randomized clinical trials of cannabis exist for GI indications, and the evidence that does exist is typically low or very low quality (such as case series or open-label studies). Further hampering a clear picture is the lack of standardization of cannabinoid products, which may contain hundreds of bioactive compounds, of which most have unknown effects. Two cannabinoids are better understood and are typically used to guide prescribing (specifically delta-9 tetrahydrocannabidiol [THC] and cannabidiol [CBD]), but these also vary substantially across strains of cannabis. Variability in inhalation or ingestion methods can also dramatically affect levels and effects of bioactive substances in the body. Given these factors, the Canadian Association of Gastroenterology (CAG) has determined that guidance is required on the issues of relevance for clinical practitioners in the area of cannabis benefits and harms and particularly so with the anticipation of increased recreational use in Canada and more widespread medical use worldwide.

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