Despite the draconian restrictions imposed on cannabis research in the U.S., a handful of doctors and scientists have been able to do limited amounts of research on medical efficacy and longterm effects. Donald Abrams, M.D. is one of them. Here he answers questions for the publication of the UCSF medical school, where he holds an appointment.

A. With regards to secondhand marijuana smoke, I do not believe that such studies have been done. In general, inhalation of products of combustion is not the ideal way to deliver a medicine.

Donald Tashkin at UCLA has spent nearly 40 years investigating the harmful effects of inhaled marijuana on the lungs - from the electron microscopy level to airway responsiveness to the development of cancer. He has made some interesting observations. Chronic cannabis use seems to be associated with an increased risk of chronic bronchitis. Tobacco smokers who also smoke cannabis, however, seem to have less of a risk to develop emphysema. Most recently he has done a case control study of over 1,300 lung cancer patients in Los Angeles and has found that regular cannabis smoking does not lead to an increase in lung cancer, and may actually be associated with a decreased risk of lung cancer.

How is that possible, you may ask? Well, actually this seems to support an animal study and a previous epidemiologic cohort study which suggests the same. It may be that the anti-inflammatory and anti-oxidant effects of some of the components of cannabis are coming into play to explain this finding. There was one study that suggested that chronic cannabis smoking could be associated with an increased risk of head and neck cancers; however, that study was flawed by not controlling for the impact of tobacco smoking, which is a known risk.

More and more basic science studies are demonstrating that cannabinoids - the active ingredients in cannabis - may actually be worth investigating as anti-cancer agents! So that is a whole new line of interesting research that may be bearing fruit in years to come!

A. To actually "prescribe" cannabis one needs to have a Schedule 1 license from the Drug Enforcement Administration and even then it is only being "prescribed" for research studies. I have a Schedule 1 license to be able to "prescribe" the marijuana that I get from the National Institute on Drug Abuse (NIDA) to participants in my research trials.

Since 1996, California physicians have had the right to discuss and recommend the use of medicinal cannabis with their patients. Generally, for their patients to be able to access cannabis from a dispensary (of course you cannot go to a pharmacy and get cannabis in this country), the doctors need to write a letter or sign a form saying that it is ok with them if their patients seek and utilize medicinal cannabis, and that they will continue to follow and care for the patient. So that is not exactly prescribing. And again, there is no official place patients can go to get their "prescription" filled except the local dispensaries, which the Federal Government is not necessarily happy about so they keep shutting them down! Not an ideal situation.

A. All of those conditions you listed have been found to be helped by cannabis. If one looks at the law in California, Proposition 215, it allows for the recommendation of medical cannabis where use has been deemed appropriate and recommended by a physician for use in "treatment of cancer, anorexia, AIDS, spasticity, glaucoma, arthritis, migraine or any other illness for which cannabis provides relief."

Are there clinical trials that have generated the evidence that cannabis is beneficial in all these conditions? No, largely because it has been virtually impossible to do such studies until recently. The creation of the UC Center for Medicinal Cannabis Research provided really the first mechanism for investigators to look at cannabis as a possible therapeutic agent. Before the CMCR was established, there was no easy way to obtain cannabis to study, other than as a substance of abuse. As you can see if you visit the site, CMCR has funded a number of studies investigating pain and spasticity uses of medical cannabis.

Many of the other purported benefits have come from anecdote. Like any other medication, people who are using cannabis for medicinal purposes should do so under the supervision of a physician and be aware that side effects and drug-herb interactions are possible.

Source: University of California, San Francisco, UCSF Today, October 18th, 2006
CMCR site: http://www.cmcr.ucsd.edu/