Insufficient Evidence to Support Use of Medical Cannabis for Rheumatologic Conditions

There is insufficient evidence to support the use of medical cannabis or cannabis-related medications for the treatment of musculoskeletal and autoimmune disorders, according to a review published in Expert Review of Clinical Immunology.

The movement toward legalization of cannabis for medical purposes, coupled with the recognized immunomodulatory, analgesic, and anti-inflammatory properties of cannabinoids, has expanded the available therapeutic options for clinicians who manage pain conditions. However, there remains substantial uncertainty across many specialties, particularly among general practitioners, regarding the prescription of such products — resulting in low prescription rates — because of a lack of comprehensive information from large trials and conflicting recommendations from different professional associations. At the same time, public pressure to prescribe cannabis for a variety of rheumatologic and chronic pain conditions continues to increase.

Investigators sought to assess the current state of evidence on the use of cannabis in medicine, with a focus on rheumatology. They reviewed animal and human clinical studies involving the use of cannabis and cannabis-derived products, primarily for the treatment of systemic rheumatic diseases.

Δ9-tetrahydrocannabinol is the main psychoactive ingredient in cannabis, and cannabidiol is the major nonpsychoactive ingredient, to which many medical benefits have been attributed.

Cannabis comes in natural and synthetic forms and can be combusted and inhaled, heated and vaporized, ingested, and absorbed through the skin or mucosa, with advantages and disadvantages associated with each method of administration. The dosing and administration route of cannabis are specific to the patient and depend on clinical and demographic variables. Combustion is generally not preferred for medical use, as it is associated with the release of toxic combustion products.

Studies on the use of cannabis in rheumatoid arthritis, osteoarthritis, systemic lupus erythematosus, systemic sclerosis, and fibromyalgia were reviewed. Results ranged from those supportive of its use for pain relief to those indicating that more research is needed. Adverse events reported were generally mild, with dizziness being most common; other adverse events included disorders of the nervous, cardiac, gastrointestinal, and vascular systems, as well as psychiatric disorders.

Despite the presence of studies supporting the benefits of cannabis, the researchers were unable to definitively conclude that cannabis or cannabis-related products are safe and effective for treatment of rheumatic diseases. They noted a gap between animal and clinical studies, as well as the paucity of studies examining long-term adverse effects. Large-scale clinical trials are necessary to examine the safety and efficacy of cannabis before it can be recommended for the management of rheumatoid arthritis, osteoarthritis, and fibromyalgia.

“The current insufficient evidences do not allow recommending any cannabinoid preparation for rheumatology patients,” concluded the authors.

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Reference

Sarzi-Puttini P, Batticciotto A, Atzeni F, et al. Medical cannabis and cannabinoids in rheumatology: where are we now? [published online September 12, 2019].Expert Rev Clin Immunol. doi:10.1080/1744666x.2019.1665997