By Igor Grant,
Friday, October 22, 2010 at midnight
The debate over Proposition 19 – the Nov. 2 initiative to legalize marijuana in California – proves once again that where there’s smoke, there’s ire. But lost perhaps in the overheated haze of political rhetoric and culture clash is an ongoing scientific effort to elucidate marijuana’s potential as a powerful pain killer for people with HIV, diabetes, spinal cord injuries and other life-altering conditions.
That effort, I fear, may go up in smoke.
For the last decade, the Center for Medicinal Cannabis Research (CMCR), based at the University of California San Diego but drawing upon scientists throughout the UC system, has conducted preclinical and clinical trials of cannabinoids, the chemical compounds active in cannabis plants like marijuana. The goal has been to provide empirical evidence, one way or another, to the question: “Does marijuana have therapeutic value?”
The answer is yes.
Three published studies, all conducted under CMCR auspices, indicate marijuana effectively blunts neuropathic pain in some people. This is pain caused by damage to peripheral nerves. It can result in numbness, prickling or tingling sensations, hypersensitivity to touch and muscle weakness. In severe cases, patients feel burning. Neuropathic pain can occur after traumatic injury or from numerous diseases, such as HIV, diabetes, autoimmune disorders and cancer.
In two studies, roughly half of patients who smoked cannabis reported 30 percent or greater pain reduction compared to placebo groups. Another study found similar relief for people with spinal cord injuries. A fourth study, not yet published, found marijuana reduced painful spasticity associated with multiple sclerosis better than placebo cigarettes.
Other research has documented that marijuana reduces pain perception and that it can be delivered effectively in vaporized doses, rather than by smoking or oral drugs. Two more studies will finish up next year.
These are admittedly small studies, but they argue for more research, not less. That may not happen. Funding for the CMCR will run out soon. The center will continue to exist, but unless new research projects are funded – unlikely in the current economy and political atmosphere – little progress can be expected. If that happens, opportunities to advance pain science and treatment may be snuffed out.
Some critics will shrug. Marijuana has a notorious reputation. It is broadly branded as a menace to society and human health, a weed without merit, reefer madness. But that’s an ill-informed point of view. Used under the guidance of a trained doctor, marijuana can benefit patients for whom other analgesics have proven inadequate or ineffective. Indeed, cannabis may be a far healthier option. It is not as physically addictive as morphine or barbiturates, whose withdrawal symptoms can involve convulsions and delirium. There is no evidence that monitored, moderate use of marijuana does physical harm. Sure, cannabis can produce psychological dependence – and heavy users may experience mild physiological withdrawal – but these symptoms are not as impairing, nor are they as dangerous as those caused by legal intoxicants like alcohol.
No one suggests that marijuana is a painkilling panacea. It is not. As a therapy, smoked marijuana has limitations. Even if it works wonderfully, it can’t be employed in hospitals or near oxygen tanks. It may not be suitable for patients with certain conditions. And there is the issue of secondhand smoke.
But these constraints and concerns should not undermine all research. Smoking marijuana may be an imperfect remedy, but there is currently no better delivery system for the active, pain-remediating elements of marijuana. Some skeptics point to marinol (dronabinol), a federally approved oral drug that contains synthesized tetrahydrocannabinol, the active ingredient in marijuana. Dronabinol is typically used to treat nausea and vomiting. As a pain killer, it is problematic because it is absorbed quite variably in different individuals, making it hard to regulate dosing based on treatment response or side effects.
In the long run, of course, the goal is to find something like dronabinol, only better. Scientists are seeking to create a whole new class of medical compounds based upon cannabinoids targeted at specific types of pain impervious to other, more traditional treatments. That can happen, but only if thoughtful people support thoughtful, continued research.
Grant is a professor and executive vice-chair of the Department of Psychiatry at the University of California San Diego. He also is director of the Center for Medicinal Cannabis Research, the HIV Neurobehavioral Research Center, the California NeuroAIDS Tissue Network and the Translational Methamphe