John R. Sharp: Why I don’t prescribe marijuana |

John R. Sharp: Why I don’t prescribe marijuana

John R Sharp, M.D., Steamboat Springs

— I read with interest your story about the Steamboat mom who is treating her 13-year-old son's autism with marijuana ("An alternative treatment," Oct. 31, 2010). The use of cannabis for treating patients is not new, and U.S. physicians prescribed it until the 1930s when marijuana was classified as a high abuse-potential drug. In 1974, marijuana was placed in the Schedule I (illegal) category of dangerous drugs. However, public referendum balloting allows for a medical prescription use of marijuana in 16 states.

So why does traditional Western medicine not prescribe marijuana for patients like this unfortunate child in your newspaper article? Since I have declined requests to write a marijuana prescription, I would like to answer that question for your readers.

The science of traditional medical practice is based on randomized, double-blinded, controlled clinical trials and there have not been any such trials with marijuana. There are very small case studies that show more marijuana benefit than there is, because of small study size, bias within the studies because of confounding variables including co-morbid disease and tobacco and alcohol use as well as the bias of political agendas concerning legalization.

Marijuana is effective in lowering intra-ocular pressure in glaucoma patients, but it takes smoking a dozen joints a day to be as efficacious as drugs that already are available. There is no evidence that marijuana is more efficacious than other available prescription medications on neuropathic pain, chronic wasting and nausea with chemotherapy. There is no evidence that autism is effectively treated with marijuana. Anecdotal stories of individual case effectiveness are not accurate measures of a medication's safety or effectiveness.

On the other hand, marijuana has well-documented abuse and dependence risks: 10 percent of regular users become addicted, compared to 15 percent with alcohol and 26 percent for opiate drugs. Moreover, just as many fatal accidents are marijuana related as alcohol related. Marijuana increases heart rate, increases pre-term miscarriages, and the risk of a heart attack is five times greater in the hour after smoking a joint.

In 2010, the Yampa Valley Medical Center emergency room has seen an epidemic of abdominal pain and cyclical vomiting in young people using marijuana. Clinical studies of the use of marijuana in this cyclical vomiting condition show that marijuana use actually aggravates the condition and produces a cycle of more marijuana producing more vomiting. Even attempts to wean off the marijuana produce a temporary increase in vomiting. Treatment begins with absolute cannabis avoidance.

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When Coloradans approved Amend­­­­ment 20 in 2000 for the use of medical marijuana, a small-scale enterprise was envisioned, not the vast entrepreneurial enterprise that confronts us. Only 3 percent of medical marijuana users are people with cancer, and only 1 percent have HIV/AIDS. Ninety percent have "severe chronic pain." Seventy percent of the 70,000 cards are issued to males between the ages of 24 and 34. About 55,000 of the cards issued are written by 15 physicians, and of these, five have been disciplined by the Colorado Medical Practice Board.

Marijuana is not subject to clinical safety and purity analyses. There is no standardized dosage. There is no post-marketing surveillance to assess adverse reactions. This lack of safety information and proof of efficacy opens the physician to negligence when he/she prescribes this drug for a patient who has an adverse outcome. I expect we will see malpractice suits brought by a patient injured from their own personal use of "prescribed" marijuana or by a person injured as a result of a patient's use of prescribed marijuana.

The vast majority of physicians will not prescribe marijuana. The current situation in our state is socio-political, not a medical debate, and these tactical maneuvers are designed to legalize the drug. To expect your medical community to "step to the plate" in this issue is a bit naive in light of our Hippocratic oath to "above all do no harm." Please leave me and my colleagues out of it.

Reference: Newsletter of the Colorado Physician's Health Program (CPHP) and comments by Doris C. Gundersen, M.D., Medical Director of CPHP., Volume 9, Issue 1, Summer 2010.

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