A study conducted by researchers from the NSW Department of Health, University of Sydney, Swinburne University, Drug and Alcohol Clinical Research and Improvement Network, and the Lambert Initiative for Cannabinoid Therapeutics, recently published in PLOS ONE, sheds light on the prescribing patterns of medicinal cannabis (MC) in Australia.
Through an online, anonymous cross-sectional survey, the study uncovered a concerning trend: the prescription of MC for conditions where evidence is lacking and in scenarios where drug interactions could pose risks. According to the authors, the research results calls for a reevaluation of prescribing practices to ensure patient safety and efficacy of treatment.
The study leveraged data from individuals using prescribed MC alone or in combination with illicit cannabis, who showed an understanding of their MC’s THC and CBD composition.
Out of 546 respondents, the majority used MC for pain management, followed by mental health, substance use, and other conditions (neurological symptoms, sleep, other, gastrointestinal symptoms, and cancer).
The analysis highlighted a significant inclination towards THC-containing products for managing conditions like back pain, aligning with Therapeutic Goods Administration (TGA) reviews that indicate some efficacy of THC and CBD in treating chronic non-cancer and neuropathic pain.
Despite the growing use of prescribed MC for various conditions, the evidence supporting its efficacy, especially for mental health issues and palliative care, remains limited. This gap suggests a cautious approach is advised, yet over 46% of study participants were prescribed MC for ailments beyond pain and epilepsy, reflecting a broad but potentially premature application of cannabis-based treatments in Australia.
Furthermore, the study highlighted significant concerns regarding potential drug interactions—a critical oversight in current prescribing practices.
Many study participants on prescribed MC also reported taking medications like opioids, benzodiazepines, and antidepressants, which could interact with THC and CBD in ways that increase sedation or impairment risks.
While MC containing THC is reported to reduce opioid dependence, the prevelant use of concurrent medications indicates a pressing need for more judicious prescribing practices that better consider the complex dynamics of drug interactions, especially given the nuanced risks associated CBD’s impact on drugs metabolised by key enzymes like CYP3A4, CYP2C9, and CYP2C19.
In concluding, the study noted a significant decrease in the likelihood of patients consuming THC-dominant MC driving shortly after use (within 3 hours), compared to those using CBD-only products. This observation underscores a cautious approach among THC consumers regarding driving, reflecting awareness of THC’s impairing effects despite the absence of legal differentiation between illicit and MC in Australia’s drug driving laws.
With medicinal cannabis prescriptions surging in Australia, this study was among the first to delve into patient feedback, revealing that current practices often sidestep the TGA’s guidelines, sometimes prescribing for conditions without any established guidance.
While the analysis highlighted the versatility of MC and an overwhelming self-reported improvement in conditions treated by MC, it also underscored the necessity for improved adherence to regulatory guidance and education of medical practitioners prescribing MC to optimise patient outcomes and safety.
Reference:
Trevitt BT, Bailey S, Mills L, Arkell TR, Suraev A, et al. (2024) Differences in prescribed medicinal cannabis use by cannabinoid product composition: Findings from the cannabis as medicine survey 2020 (CAMS-20) Australia-wide study. PLOS ONE 19(2): e0297092. https://doi.org/10.1371/journal.pone.0297092