THE Health Research Board (HRB) has published the results of its review of the evidence on the safety and effectiveness of prescribed medical cannabis in the country.
The report, which was published on Tuesday January 23, details the effects of medical cannabis prescribed for certain conditions in Ireland, including nausea and vomiting in cancer and spasticity in multiple sclerosis.
The report also shares “promising” evidence of significant benefit for neuropathic or nerve pain, which can occur in conditions such as multiple sclerosis, diabetes or spinal cord injury.
For most other conditions, including anxiety and pain related to cancer, rheumatic diseases and fibromyalgia, there is no “conclusive evidence” supporting the effectiveness of prescribed medical cannabis, according to the report.
Regarding the safety of prescribed cannabis, the study found that although serious side effects from cannabis do not appear to be common, some side effects such as dizziness, dry mouth, sedation and headaches head may occur.
The likelihood of other adverse effects, such as drowsiness, nausea, and psychiatric disorders, is mixed.
The study was carried out as part of a review by the Ministry of Health of the current medical cannabis access program (Medical Cannabis Access Program –MCAP). Currently, only patients with one of three eligible conditions, namely chemotherapy-induced nausea and vomiting, treatment-resistant epilepsy, and spasticity associated with multiple sclerosis, can access cannabis-based medicines under this program, which was launched in 2019.
Dr Kathryn Lambe, research fellow at HRB and lead author of the report, said: “Our review indicates that there is some evidence to support the use of prescribed medical cannabis for conditions such as nausea and vomiting due to chemotherapy, spasticity in multiple sclerosis, and management of neuropathic pain. »
“However, for most other results, the conclusions are inconsistent at best. This study will help inform decision-making regarding future policy on the use of prescribed medical cannabis, as well as input from patient groups, clinicians and service planners.”
Recommendations for future research
Covering research conducted over the past 30 years on the use of medical cannabis prescribed to adult patients only, the study evaluated data from 47 journals, across a number of medical conditions ranging from cancer, multiple sclerosis and rheumatic diseases, pain, mental health and neuropsychological conditions.
It focused on data relating to prescribed medical cannabis containing natural or synthetic CBD or THC or their derivatives.
The authors concluded that the body of research they reviewed was “fragmented” with a “low degree of certainty in the evidence for most findings.”
They made a number of recommendations for future research to improve the quality of clinical data on medical cannabis. These include subgroup analyzes for different types of pain, the use of modern treatments as active comparators rather than placebos, and studies with different treatment arms to define the optimal ratio of THC and of CBD for the indication in question.
Informing future policies
According to the report, the study's findings will inform the Ministry of Health's position on the suitability of medical cannabis products for various clinical indications, as well as future responses to communications regarding the prescribing of cannabis products.
Mairead O'Driscoll, chief executive of the HRB, said: “It is essential that health policies are based on the most recent evidence, including in areas where existing research is not sufficiently developed to draw conclusions solid. By conducting this type of review over time, the HRB can continue to provide policymakers with evidence to inform their decisions as research evolves. »
A “missed opportunity”
MCAP has already faced criticism from patients due to its “restrictive” nature, with fewer than 100 people having enrolled in the program so far. The outcome of the HRB review cast doubt on whether the program could be expanded.
Patient advocates expressed disappointment that the study did not include concrete evidence or address Irish patients who say they benefit from medical cannabis, many of whom traveled abroad to access it.
“The HRB report highlights the need for more detailed analysis of medical cannabis,” says legal researcher and drug policy advocate Natalie O’Regan.
“In 2024, we are still hearing that more research is needed to avoid expanding access to cannabis. The report did not speak with current MCAP patients and missed the opportunity to collect real-world data that is available at their doorstep. Ultimately, it is patients who will suffer the consequences of limited access to a medicine they may find invaluable.”
She added: “One positive is that the report found evidence that supports medical cannabis in neuropathic pain, and I hope this will expand in the near future.”
