Up to 50 per cent of patients with Parkinson’s disease have reported feeling pain and discomfort on a daily basis. This pain is often associated with muscle rigidity and fluctuations in levodopa. Some patients also experience ‘off-dystonia’: twisting and repetitive muscle contractions which affect the toes and feet, resulting in painful cramps and posture.
Current treatments involve using levodopa or other dopaminergic drugs to regulate dopamine levels in the brain during ‘off’ periods, when pain may be pronounced. However, many patients experience severe burning, aching and stabbing pain that does not respond to medications, making it more challenging to treat.
Dr. Fox’s proposed study aims to examine the tolerability of mixed cannabinoids (including the psychoactive component, delta-9-tetrahydrocannibinol [delta-9THC], and non-psychoactive compound cannabidiol [CBD]) as a method of treating pain in Parkinson disease. Cannabinoids are used in therapies to relieve pain in patients with multiple sclerosis and advanced types of cancer. However, there have been no randomized clinical trials investigating cannabinoids in pain management for people living with Parkinson’s disease.
The study will use an oral cannabis product available in Canada, as a mixed oil solution, that contains both delta-9THC and CBD. A Phase I study will be conducted to determine the range of maximum tolerated dose and to provide preliminary data on the effectiveness of each type of oil in treating pain symptoms. The results of this first phase will inform a second phase of the clinical trial, and pave the way for future study of cannabinoids in treating Parkinson’s.
While the use of medical cannabinoids remains a highly controversial topic, and there are still many unknowns, Dr. Fox and her team ultimately seek to evaluate the safety and tolerability of using this approach as a possible way of reducing pain associated with symptoms of Parkinson’s disease, in order to enhance patients’ overall quality of life.