Cannabidiol, known as CBD, makes up about 40% of extracts from the cannabis plant. It is said to be non-psychoactive, and to counteract the psychoactive compounds known as THC. Researchers at the Canadian Department of Agriculture have found that hemp - the type of cannabis grown for fiber or in the wild in temperate climates - is low in THC and high in CBD. The plant that originated in hot climates has different genetics, and is high in THC but low in CBD. Most cannabis currently grown for street and medicinal use is the latter type, bred to be high in THC, low in CBD. This is important for growers, as CBD is known to block the effects of THC. In other words, CBD prevents a marijuana ‘high’. In addition, CBD has been found to have interesting and promising medicinal uses. Research reports on CBD are now found in the medical literature.
Pain/Sativex : Several recent studies have shown that CBD, often combined with THC, is effective against pain in patients with advanced cancer whose pain is not controlled by medicines like morphine.. Patients appreciate the lack of hallucinogenic side effects. CBD/THC extracts have also been helpful with pain and spasticity in patients with multiple sclerosis. Canada released a medicine called Sativex in 2005, which was licensed for use in patients with multiple sclerosis and cancer pain. Sativex is a mouth spray; its full effect is achieved in about an hour. It is a mixture of THC and CBD, derived from the whole plant. Sativex is currently being used in England and Spain, for multiple sclerosis, severe nerve pain, malnutrition due to AIDS, and nausea/vomiting from chemotherapy. The US FDA has approved Sativex for certain clinical trials for cancer pain.
Cancer: Research has shown that CBD may work as an anti-cancer agent with low toxicity. Researchers at CPMC in San Francisco have been working on the ability of CBD to inhibit the growth and spread of breast cancer cells in a mouse model. If the work goes well, clinical trials of CBD in human breast cancer patients may take place. CBD is also being studied as a therapy for leukemia and brain tumors known as gliomas.
Other Uses: CBD has been tested in schizophrenia, epilepsy, ulcerative colitis, and Crohn’s Disease. As yet, there are no definitive answers as to its efficacy.
CBD in the leaf: Some people with severe pain are chewing the green leaves of marijuana plants for relief. The balance between THC and CBD in the leaf is said to be helpful without giving hallucinations or a ‘high’. People differ in their response to the leaf. They find that if the leaf is green and newly harvested, they can get pain relief and stay sober, even energized, by simply chewing it. If leaves are heated or aged, however, certain effects of THC are felt, and users can become tired and feel unwell. Because of current laws on individual use, this is anecdotal information.
November Ballot: Californians will be voting in November on an initiative to legalize the recreational use of marijuana for those over 21, and to allow small residential cultivation of the plant. Local governments, but not the state government, will be able to tax and regulate marijuana. A bill is pending in the California legislature that would legalize, tax and regulate marijuana, which could generate income for the whole of California. Many proponents say that the initiative is the first step toward a rational drug policy, and will save millions by not putting users in prison. Opponents are anxious about addiction, driving under the influence, use of the drug by more teenagers, and a further proliferation of pot dispensaries. Stay tuned for a detailed discussion of the pros and cons of this important issue as November approaches.
Sadja Greenwood, MD, MPH back issues at on this blog