CASE REPORT
Annie Wang, Anita Lo, Kiran Ubhi, and Thomas Cameron
Can J Hosp Pharm. 2021;74(2):156-8
INTRODUCTION:
The Arthritis Society, a Canadian health charity, describes osteoarthritis (OA) as “a progressive disease of the whole joint that leads to breakdown of joint cartilage and underlying bone.”1 OA can affect any joint in the body, with symptoms that differ from one individual to the next, the most common being joint pain, joint stiffness, and swelling. OA is the most common form of arthritis and currently affects more than 10% of the adult population in Canada.2 The prevalence of OA increases with age; as such, with aging of the Canadian population, the general prevalence of arthritis is expected to increase to 20% (or 7 million) by 2031.3Consequently, there is a powerful impetus to find effective solutions to manage this condition.
Current pharmacological approaches to the treatment of chronic pain associated with OA rely primarily on long-term use of acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and injectable corticosteroids, and may include other drugs such as gabapentin. Over-the-counter supplements, such as glucosamine and chondroitin, may be considered, given that they may provide symptomatic relief for some patients.4 The use of these medications has been the mainstay of therapy for quite some time; however, some patients continue to experience uncontrolled pain while taking the usual therapies. As such, cannabis and cannabinoids are now being investigated as adjuncts for the treatment of OA-related pain.5 The shift in therapeutic cannabis research is based on the realization that, among the diverse array of biological activities exhibited by cannabinoids, the endocannabinoid system has been shown to play a role in pain perception, as well as modulating inflammation.6,7 This report describes an elderly patient with severe OA of the hips, knees, and shoulders who used cannabis products, including cannabidiol (CBD) and tetrahydrocannabinol (THC), in an attempt to manage pain.
CASE REPORT:
An 85 year-old woman with severe OA was admitted to a long-term care home on August 15, 2018.* Her OA was noted to be particularly severe in the left hip and knee, an assessment that was confirmed by radiography. She had difficulty with transfers secondary to her OA and was non-ambulatory; therefore, she used a wheelchair for mobilization. Her medical history included atrial fibrillation, type 2 diabetes mellitus, and open-angle glaucoma. She reported an allergy to penicillin. Medications before admission included apixaban 5 mg twice daily, metoprolol 50 mg twice daily, ramipril 5 mg twice daily, atorvastatin 20 mg daily, insulin glargine 22 units in the morning and 15 units at bed-time, and 1 drop of latanoprost 0.005% in each eye once daily at bedtime. Her pain control medications were acetaminophen 650 mg daily, diclofenac gel 10% (compounded) twice daily, gabapentin 300 mg 3 times daily, hydromorphone 2 mg 4 times daily and 2 mg hourly as needed (PRN), and fentanyl patch 75 μg/h every 3 days. The resident denied the use of any over-the-counter medications or natural health products.
Until December 2018, the resident was using hydromorphone 1 mg PRN, 5 to 7 times monthly; at that time, however, her pain worsened, and PRN use of hydromorphone also increased substantially, up to 5 to 7 times daily. After evaluation at a cannabis clinic and subsequent assessment by the general practitioner, the resident was started on CBD Oil Drops (CannTrust Inc) at a concentration of 25 mg/mL. The initial dosage was 0.2 mL (5 mg) orally twice daily; the dose was titrated up by 0.2 mL every week to reach 3.0 mL (75 mg) orally twice daily in February 2019. Immediately upon the introduction of CBD oil, her use of PRN hydromorphone declined to 3 to 5 times daily. The patient noted that the CBD made her “sleepy sometimes”, but no other adverse effects were reported. We were encouraged by the resident’s reduced analgesic requirements, which were not accompanied by any self-reported change in perceived pain. However, the reduction in PRN use was transient, lasting only 1 week, and use of hydromorphone subsequently returned to the levels that were in use immediately before initiation of CBD oil (i.e., 5–7 times daily), even as the resident continued taking CBD oil at a dosage of 3.0 mL orally twice daily.
*The patient provided informed consent for publication of this report.
Future investigations should take into consideration the low, yet highly variable oral bioavailability of CBD. Perhaps inhalation, mucosal administration, or administration in the form of lipid nanoparticles will lead to more accurate and reliable dosing.17 Excessively high doses of CBD can yield unpleasant adverse effects, such as major fatigue and dizziness; therefore, subsequent studies should be conducted to decipher what dose and titration method are appropriate, especially for elderly patients, and these studies should include careful monitoring for adverse events. Additionally, future studies should evaluate the clinical utility of CBD use for different populations, to determine who is most likely to benefit.
CONCLUSION:
This case report suggests the potential for adjunctive use of cannabinoids in managing OA pain. Positive outcomes from the use of CBD oil in this case included a small reduction in PRN hydromorphone use, a consistent post-dose reduction in pain, and slight improvement in terms of functionality and participation relative to the situation in the months before the patient started CBD treatment. The changes observed in this case might have resulted from a placebo effect; as such, it will be important for high quality clinical trials to be conducted to evaluate the efficacy of cannabinoids in treating OA pain.
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