Arthritis is a common debilitating disease affecting roughly 50 million adults and 300,000 children within the United States. Although many people have heard of or suffer from arthritis, it is not an actual disease, but rather a collection of symptoms that relate to pain and inflammation of joints. There are several different types of arthritis. The more commonly experienced is degenerative osteoarthritis which is the result of a breakdown of the cartilage surrounding articulating joints, resulting in bone-on-bone “grinding” that results in pain, swelling and limited range of motion. Risk factors for the development of degenerative osteoarthritis include age, family history, excess weight, and previous injury. This type of arthritis can make it very difficult for individuals to participate in normal life activities leading to poor quality of life, and if severe may require surgery to replace the problematic joint. Living an active life and limiting repetitive motions is best to prevent the onset. The typical course of treatment is with Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), however over-medication puts one at risk for stomach ulcers or liver damage.
The other most common type of arthritis is inflammatory based. This happens in generally healthy individuals when the immune system begins to act inappropriately and mistakes the body’s joints and cartilage as “non-self” and begins attacking the tissue. The result of this is chronic high levels of inflammation in the articulating joints leading to swelling, redness, pain, limited range of motion, and in severe cases joint deformities. The more common names for this type of arthritis are rheumatoid arthritis and psoriatic arthritis. The cause of this condition is not fully understood, but is thought to be a dynamic interplay between genetic and environmental factors, such as smoking, that lead to autoimmunity. Treatment relies on disease-modifying antirheumatic drugs (DMADs) that reduce inflammation, swelling, and prevent further joint deformities. This type of treatment targets cytokine tumor necrosis factor to reduce inflammation, although it is associated with negative side-effects such as systemic immunosuppression.
Individuals suffering from either degenerative osteoarthritis or inflammatory arthritis do not often experience relief from conventional medications or therapies. The potentials risks associated with surgery, even if there are no complications, further leaves individuals skeptical and hesitant to seek out these treatment modalities. This has led individuals desperately seeking alternative, non-pharmacological therapies to provide relief from their symptoms and hopefully reverse their condition.
Cannabidiol (CBD) has been studied extensively within the last couple decades by researchers hoping to elucidate a new therapy for reducing the inflammation and pain associated with arthritis. CBD is one of over 80 different cannabinoids produced by the Cannabis sativa plant that is non-psychoactive, which is associated with the more commonly known tetrahydrocannibinol (THC) cannabinoid, and is non-habit forming. Administration of CBD has not been associated with any adverse events or side-effects and is deemed safe as it has been well tolerated with long term usage of dosages up to 1,500mg per day.
A July 2016 study conducted by Hammel et al, determined that topical transdermal application of CBD oil resulted in marked decrease in pain and inflammation with no side-effects in a well studied rat model of arthritis. The researchers observed this to be the best method of application because CBD is fat-soluble and when administered orally does not get absorbed well due to first pass metabolism in the liver. CBD has low affinity for CB1r and CB2 receptors of the endocannabinoid system compared to THC and its mechanism of action is still not fully understood. The researchers hypothesize that CBD inhibits signalling in the GPR55 receptors and TRP channel superfamily. It is further believed that oral-administration is associated with reduced pro-inflammatory cytokine release that is dose-dependent. A transdermal dose of 6.2mg/kg was determined to be the most efficacious at reducing pain, swelling and inflammation, with lower doses not providing any results and higher doses not yielding any further benefits.
The other well known study exploring the potential benefits of CBD for arthritic pain and inflammation in a well accepted mouse model was conducted by Malfait et al in 2000. The researchers compared oral administration with intra-abdominal injection of CBD oil in various doses. A similar inverted U-shaped dose-response curve was noted with the most efficacious orally administered dose being 25mg/kg and 5mg/kg for intra-abdominal injections. The study noted that CBD was associated with reduced pain, swelling, inflammation, and progression of disease, due to a combination of potent immunosuppressive activity, dramatically reduced tumor necrosis factor, and the inhibition of the release of reactive oxygen species within the synovium of joints which produce inflammation. The authors conclude that although CBD’s mechanism of action is not yet fully understood, it may be a valuable treatment of arthritis as well as other chronic inflammatory conditions that is well tolerated, safe, non-psychoactive, does not interfere with normal behaviors, and is not associated with any adverse side-effects.