As the use of prescribed medical cannabis products continues to expand, understanding the real-world incidence and nature of associated adverse events (AEs) becomes increasingly important. While controlled clinical trials offer valuable insights, they often have limitations regarding patient diversity and product types. A recent retrospective analysis, published in Frontiers in Pharmacology, sheds light on adverse events reported by patients within the Minnesota Medical Cannabis Program.
Understanding Adverse Events in Medical Cannabis Use
Researchers from the University of Minnesota and collaborating institutions conducted a retrospective analysis of adverse events reported between 2015 and 2021. The data originated from a centralised call centre, SafetyCall International, which collected reports from individuals receiving medical cannabis products from a single licensed manufacturer in Minnesota. This program provides dosing supervision by pharmacists and requires patients to be certified for specific qualifying conditions by a licensed practitioner.
Study Design and Reported Symptoms
The study analysed 237 calls from 225 individuals, detailing a total of 692 symptoms. Most of these calls (79.3%) came directly from medical cannabis consumers. The reported adverse events were classified by severity, with the majority (71.7%) considered minor. Events classified as “major” typically involved hospitalisation, prolongation of hospitalisation, or significant disability. Information not directly related to AEs, such as product efficacy issues or device breakage, was excluded from the analysis.
Associations with Product Types and Dosing
The study identified associations between reported adverse events and specific product characteristics:
- Product Type: THC-dominant products were associated with 39.8% of the reported adverse events.
- Formulation: Capsule formulations were implicated in 36.8% of the overall reported events.
- Dose and Severity: Among individuals for whom dose data was available, those experiencing moderate adverse events were associated with significantly higher daily delta-9-tetrahydrocannabinol (THC) doses compared to those with minor adverse events.
These findings suggest that both the cannabinoid profile and the delivery method may influence the likelihood or severity of adverse events. The study also noted that purified cannabidiol (CBD) and THC have complex pharmacokinetics, with significant inter-individual variability in drug exposure and physiological responses. Factors such as high lipophilicity, food effects on absorption, bioavailability based on delivery forms, and first-pass metabolism can contribute to this variability.
Implications for Patient Care and Pharmacovigilance
The researchers reported that adverse events, though infrequently reported to the centralised system, were often clinically meaningful. A notable finding was that 32.5% of individuals discontinued their medical cannabis treatment following an adverse event report. This highlights the impact these events can have on patient adherence and overall treatment pathways.
The voluntary nature of reporting to such a system likely means that the actual burden of adverse events is underestimated, as only more severe or bothersome events may prompt a call. This underscores a critical need for enhanced pharmacovigilance systems to capture a more comprehensive picture of patient experiences.
Furthermore, the study discussed potential drug-drug interactions, noting that CBD and THC are primarily metabolised by cytochrome P450 (CYP) enzymes. Both cannabinoids have been shown to inhibit certain CYP enzymes in vitro, which could lead to clinically relevant interactions, particularly with commonly prescribed psychotropic medications like antidepressants. As previously reported by Hemp Gazette, understanding the pharmacology of THC in a medicinal context and Cannabidiol (CBD) is important for informed patient management.
The authors conclude that these findings emphasise the necessity for ongoing research into the long-term safety and public health implications of cannabinoid therapies, especially for patients with complex medical conditions who may be using multiple medications.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Hemp Gazette does not provide medical recommendations, diagnoses, or treatment plans. Always consult a qualified healthcare practitioner before making any decisions regarding your health or any medical condition. Statements concerning the therapeutic uses of hemp, cannabis, or cannabinoid-derived products have not been evaluated by Australia’s Therapeutic Goods Administration (TGA). Medicinal cannabis products in Australia are accessed via prescription pathways under TGA regulation.
