Medical Marijuana is legal in 23 states and Washington, D.C. Many of the remaining states have proposals on the books for legalization. Marijuana is a political hot-button issue. But there should be a greater focus. Does marijuana work as a proven medical therapy?
According to new studies, “the evidence for medical marijuana to treat conditions other than the FDA indications and chronic pain, neuropathic pain, and spasticity associated with multiple sclerosis is either equivocal or weak,” said Kevin Hill, MD, Harvard Medical School.
In a JAMA review of 79 relevant trials involving medical cannabis or cannabinoids, researchers — led by Penny F. Whiting, PhD, University of Bristol, United Kingdom — found:
- Moderate-quality evidence to support the use of cannabinoids for the treatment of chronic pain and spasticity
- Low-quality evidence associated with improvements in nausea and vomiting due to chemotherapy, weight gain in HIV infection, sleep disorders, and Tourette syndrome.
- An increased risk of short-term adverse effects (AEs) including psychiatric, nervous system and/or connective tissue disorders.
“There is some evidence to support the use of marijuana for nausea and vomiting related to chemotherapy, specific pain syndromes, and spasticity from multiple sclerosis,” according to an accompanying editorial by Deepak Cyril D’Souza, MD, and Mohini Ranganathan, MD, Yale University School of Medicine. “However, for most other indications that qualify by state law for use of medical marijuana, such as hepatitis C, Crohn disease, Parkinson disease, or Tourette syndrome, the evidence supporting its use is of poor quality.”
The greatest response to medical marijuana was found in the 28 studies of nausea and vomiting due to chemotherapy. “The average number of patients showing a complete nausea and vomiting response was greater with cannabinoids (dronabinol or nabiximols) than placebo,” according to the authors. However, “none of them reached statistical significance.”
Similar results were found in four studies of appetite stimulation in HIV/AIDS. “There was some evidence that dronabinol is associated with an increase in weight when compared with placebo,” said the researchers. “More limited evidence suggested that it may also be associated with increased appetite, greater percentage of body fat, reduced nausea, and improved functional status.”
However, as with the chemo studies, the results of appetite stimulation in HIV/AIDS failed to reach statistical significance.
One of the larger problems regarding medical marijuana is a lack of uniformity in the U.S., where the FDA requires evidence from at least two large clinical trials prior to approval. But the differences in usage and indications among the states makes that standard difficult to achieve.
“For example, in Connecticut, psoriasis and sickle cell disease but not Tourette syndrome qualify, even though the supporting evidence for all three conditions is uniformly of very low quality,” according to D’Souza and Ranganathan. “These differences reflect inconsistencies in evaluating and applying current evidence toward decision making about qualifying indications for medical marijuana use.”
And there are a host of legal issues for the physician prescribing marijuana, which is listed as a Schedule I drug that has a high potential for abuse.
“It is not known if malpractice insurance will cover liability attributable to physicians certifying medical marijuana use,” said D’Souza and Ranganathan. “Since medical marijuana is not a life-saving intervention, it may be prudent to wait before widely adopting its use until high-quality evidence is available to guide the development of a rational approval process.”
By Brad Broker