Medical Marijuana: The State of the Science

Michael E. Schatman, PhD


February 06, 2015

In This Article

Physical Health Applications of CBD

The vast literature on CBD provides a reasonable evidence basis for the treatment of several physical and psychological conditions. As early as 1978, published data suggested that CBD administration was associated with freedom from seizures for 3 months[95] and reduced seizure frequency in patients with epilepsy.[96] Results of an unpublished placebo controlled trial from 1990 also suggested a reduction in seizure frequency.[116]

In contrast, a recent Cochrane review concluded that there were insufficient high-quality studies to draw a reliable conclusion regarding efficacy, despite no reports of adverse events.[117] Nevertheless, in a recent review, Cilio and colleagues[118] noted that "pure CBD appears to be an ideal candidate among phytocannabinoids as a therapy for treatment-resistant epilepsy."

Patients with treatment-resistant pediatric epilepsies, such as Dravet syndrome and Lennox-Gastaut syndrome, may potentially benefit from CBD.[119] Preliminary data from a phase 2/3 US clinical trial in 12 children with Dravet syndrome have been promising,[120] prompting future plans to expand the study in the United Kingdom.[121]

CBD has also been evaluated for the treatment of Parkinson disease. Recently, investigators found that CBD reduced the frequency of rapid eye movement sleep behavior disorder in patients with Parkinson disease, with no apparent side effects.[122] Another recent study determined that although CBD did not significantly reduce motor symptoms and general symptoms of Parkinson disease, it significantly improved well-being and quality of life.[123] In patients with dystonic movement disorders, CBD was found to reduce dystonia by 20%-50%.[124]

A study of patients with intractable neurogenic symptoms from multiple sclerosis, spinal cord injury, brachial plexus injury, and limb amputation due to neurofibromatosis found that pain relief with CBD was significantly improved compared with placebo, without unwanted side effects.[125] However, a trial in patients with intractable cancer pain found only a nonsignificant reduction in pain associated with CBD compared with placebo.[81] This may have been due to the low dose of CBD used: 20-30 mg oromucosally once daily. Although numerous studies of pain management have used combined THC/CBD, the relatively new understanding of the anti-inflammatory and antispasmodic benefits of CBD have limited the number of clinical trials of CBD monotherapy that have been published.

Hundreds of animal and human cell-line studies support the investigation of CBD for the treatment of various types of cancer. Given its safety profile and the preclinical data supporting its antiproliferative and proapoptotic effects and interference with several mechanisms in oncogenesis, phase 2 studies are now planned for CBD monotherapy in the treatment of solid tumors.[126] In addition, the US Food and Drug Administration recently granted a manufacturer orphan drug designation for synthetic CBD as a treatment for glioblastoma multiforme and glioma, both of which are highly treatment-resistant malignancies.[127]


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