WESTPORT, Aug 01 (Reuters Health) - Daily oral treatment with cannabidiol, the primary nonpsychoactive component of marijuana, can substantially limit the severity of joint damage and clinical disease in mice with chronic, relapsing collagen-induced arthritis, a condition similar to rheumatoid arthritis in humans.
The finding raises questions regarding the potential use of this marijuana component in the treatment of arthritis, according to a report in the August 15th issue of Proceedings of the National Academy of Sciences that is being released Tuesday in the journal's electronic version.
Dr. M. Feldmann, of the Kennedy Institute of Rheumatology in London, UK, and colleagues found that both oral and systemic cannabidiol significantly reduced the severity of joint damage and the extent of clinical disease in acute and chronic murine models of arthritis.
However, systemic administration of the agent appeared to be more effective than oral administration. Systemic administration was able to increase the number of mice with unaffected feet (the location where joint disease was measured) from 0% in controls to 34% and decrease the number of moderately or severely affected feet from 69% to 40%. Of mice treated orally with cannabidiol, none had unaffected feet but only 25% had severely affected feet, compared with 75% of controls.
Regardless of the route of administration, lower doses of the drug were more effective than higher doses. For systemic administration, a 5-mg/kg dose offered "optimal suppression of disease," while 25 mg/kg was the optimal dose for oral administration.
The scientists point out that whether the effects of cannabidiol are caused by an active metabolite of this compound or require the complete compound remains unclear, as do the mechanisms underlying the effects of cannabidiol on arthritis and the safety of the drug for long-term use.
In a related commentary that will be published on August 15, Dr. Stephen
E. Straus, of the National Institutes of Health, Bethesda, Maryland, discusses
whether the therapeutic use of marijuana components is justifiable. He
concludes that the safety and efficacy of cannabidiol as a treatment for
arthritis are conceivable, and that the time has come for "critical scrutiny"
of the therapeutic effects of cannabis constituents as compared with whole-plant