Still widely controversial, "medical marijuana" refers to the smoked form of the drug. It does not refer to the synthesized version of THC, one of the active chemicals in marijuana, that's available in a medication called Marinol. The FDA first approved Marinol (dronabinol) in 1986 for nausea and vomiting from chemotherapy. It later approved its use for nausea and weight loss from AIDS.
The history of medical marijuana
Medical marijuana was prescribed by doctors until 1942. That's when it was taken off the U.S. pharmacopoeia, the list of commonly available drugs.
"Marijuana has been a medicine for 5,000 years," says Donald I. Abrams, MD. "That's a lot longer than it hasn't been a medicine." Abrams, who is an oncologist and director of clinical research programs at the Osher Center for Integrative Medicine at the UCSF School of Medicine in San Francisco, is one of a handful of top-flight doctors in the country researching medical marijuana. "The war on drugs is really a war on patients," he says.
So why research medical marijuana when a pill, Marinol, is now available?
Marijuana -- the plant's Latin name is cannabis -- has a host of components called cannabinoids. These components may have medicinal properties.
"There are 60 or 70 different cannabinoids in marijuana," says Abrams. Marinol contains only one cannabinoid -- delta-9 THC. When THC is isolated from the plant, other ingredients are lost, including those that might be buffering any adverse effects of taking "straight" THC. "In Chinese medicine," Abrams says, "they prescribe whole herbs and usually combinations of herbs."
Abrams goes on to point out that, "In 1999 the Institute of Medicine did a report -- Marijuana and Medicine. And they said, in fact, that cannabinoids have benefit in relief of pain, increase in appetite, and relief of nausea and vomiting."
Is medical marijuana legal?
The federal government, in the Controlled Substances Act of 1970, placed drugs into five groups called "schedules," driven by three criteria:
- potential for abuse or addiction
- medical usefulness
- dangers of abuse or addiction, both physically and psychologically
Marijuana, LSD, and heroin were all initially placed in Schedule I -- the most addictive, and least medically useful, category.
To further entangle the legal issues, several states have passed their own controlled substance laws that conflict with federal laws. That includes drug policy reforms and "compassionate use" laws that allow patients with terminal and debilitating diseases to use medical marijuana. In order to be able to use it, a patient needs to have documentation from a doctor.
The American Chronic Pain Society says in ACPA Medications & Chronic Pain, Supplement 2007: "Some states allow the legal use of marijuana for health purposes including pain, while the federal government continues to threaten physicians with prosecution for prescribing it."
The uses of medical marijuana
"Medical marijuana has many uses," Abrams says. "It increases appetite while decreasing nausea and vomiting. It also works against pain and may be synergistic with pain medications, helps people sleep, and improves mood. I think it's a shame that we don't allow people to access that medicine."
Medical marijuana doesn't "cure" disease. But patients worldwide have used it to relieve a variety of symptoms, including:
- increased intraocular pressure from glaucoma
- nausea and vomiting from chemotherapy for cancer
- pain, muscle spasticity, and insomnia from spinal cord injury
- pain, stiffness, and muscle spasticity from multiple sclerosis
- weight loss and loss of appetite from HIV
In 2003, Abrams published a study in the Annals of Internal Medicine on the interaction between medical marijuana and protease inhibitors in AIDS patients. "We showed that there was no real downside to smoking cannabis for these patients. It didn't interfere with their immune system. In fact, it might have been beneficial to their immune system in the end."
The pros and cons of medical marijuana for pain
Abrams found that medical marijuana worked for patients with HIV and peripheral neuropathy (painful, damaged nerves). That study was published in TheJournal of Neurology in 2007. "We did a randomized, placebo-controlled clinical trial that demonstrated that smoked cannabis was effective in this situation," says Abrams. "The people who say there's no evidence that smoked marijuana has any medicinal benefits really can't say that anymore. The drug was quite comparable to the best available treatment we currently have for painful peripheral neuropathy."
Not all doctors agree.
"I see no role for it in pain management," says Charles Chabal, MD. Chabal is a pain management specialist at Evergreen Hospital in Kirkland, Wash. "You'll certainly find doctors who'll be very supportive and write prescriptions for medical marijuana. But it's how the individual physician reads the data and the evidence. There's no doubt it makes you feel good, but so does alcohol."
Chabal continues, "Another problem I have with marijuana is that it's herbal, untested, and you never know what you're getting when you buy it."
Chabal doesn't bring up medical marijuana with his patients. "Some patients have asked me about it. They want me to write a prescription for medical marijuana. But that's not something I do. I don't want to be known as 'the medical marijuana doctor.' Already, doing pain management, one of the big things I need to sort out are the patients who are using pain medications appropriately versus those who are abusing them. We have a lot of social responsibility with that.
"I'm not aware of any evidence that medical marijuana is one of the tools we'd use to improve physical and social function, including interaction with loved ones and family -- all key determinants of quality of life," says Chabal.
The "poor delivery" argument
Robert L. DuPont, MD, is clinical professor of psychiatry at Georgetown University Medical School and president of the Institute for Behavior and Health, a nonprofit dedicated to reducing illegal drug use. He asks, "Is smoked marijuana a reasonable, safe drug delivery system for any medicine for any illness? That's the threshold question. The answer, to me, is transparently 'no.'"
DuPont continues, "If there are any chemicals or any combination of chemicals in smoked marijuana that are ever shown to be valuable for any illness, including fibromyalgia, I'm all for it -- meaning prescribing purified chemicals in a known dose. No doctors prescribe burning leaves to treat any illness."
An estimated 400 chemicals co-exist in marijuana, but marijuana smoke has as many as 2,000 chemicals, says DuPont. "Would you really want to prescribe 2,000 chemicals in a mix where you don't know what it is and call that a medicine?"
DuPont says it's important to test the chemicals in marijuana that might treat fibromyalgia. "If one passes muster as safe and effective, that's great. Science works with purified chemicals in controlled doses."
In fact, the Institute of Medicine's 1999 report called for research into "new delivery mechanisms" for marijuana that don't involve inhaling harmful smoke.
Abrams designed a study that compared smoking cannabis to using it in a vaporizer, a smokeless delivery system. "Once we demonstrated that cannabis was effective in neuropathy patients," he says, "we knew people would say it's not right for patients to smoke a medicine." The study demonstrated that smoking and vaporization yielded pretty similar concentrations of THC in the bloodstream. It also showed there was less expired carbon monoxide -- a marker for toxic or noxious gases -- in the group that was vaporizing." He published the study in The Journal of Clinical Pharmacology and Therapeutics in 2007.
New cannabis drugs
The search for new cannabis-based drugs continues. One preliminary Canadian study made a splash in February 2008, announcing that a new marijuana-based compound -- nabilone -- significantly reduced pain and anxiety for 40 fibromyalgia patients in Manitoba. Nabilone has been used in Canada to treat nausea during chemotherapy.
Marinol is the only cannabinoid currently approved for use in the U.S. It's expensive -- about $4,000 a year -- and only an estimated 10% to 20% of the THC gets into the bloodstream after metabolism.
The hurdles of research
Researching the medical value of marijuana is not for the faint of heart. Getting funding, federal approvals, and results published -- not to mention the drug itself, which only is available from the National Institute on Drug Abuse -- are all uphill battles.
When he conducts a study, Abrams takes extra steps to ensure safety since marijuana is a controlled substance. He hospitalizes his patients, without visitors, for the duration of the research study. Even so, he says, "It's still not easy to enroll patients in medical marijuana studies. And that makes it difficult to accumulate data."