Minnesota’s medical marijuana program begins today. The program is one of the strictest in the country. Extracts of marijuana plants will be available to patients in only pill, oil or vapor forms and at only eight dispensaries within the state.
And to qualify for a prescription, you must have one of nine medical conditions: cancer, glaucoma, HIV/AIDS, Tourette syndrome, amyotrophic lateral sclerosis (ALS), seizures (such as those characteristic of epilepsy), severe and persistent muscle spasms (such as those characteristic of multiple sclerosis), Crohn’s disease, or a terminal illness that associated with severe pain, nausea, vomiting or other designated symptoms.
But, as the title of an editorial published last week in the Journal of the American Medical Association (JAMA) asks, have Minnesota and the 21 other states with medical marijuana laws put “the cart before the horse”?
In other words, do we have good, solid evidence that marijuana (cannabis) can actually help people with those nine — or other — debilitating medical conditions?
A new comprehensive review, conducted by an international team of experts and published in the same issue of JAMA, suggests no. They looked at 79 clinical trials involving more than 6,400 patients and found that the evidence in support of the medical benefits of marijuana was weak at best.
“For most of the conditions that qualify for medical marijuana use, the evidence fails to meet [U.S. Food and Drug Administration] standards,” write the authors of the editorial, Yale University psychiatrists and researchers Dr. Deepak Cyril D’Souza and Dr. Mohini Ranganthan.
“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,” the two doctors add. “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.”
Inconsistencies and unknowns
The review’s findings raise several important issues, which D’Souza and Ranganthan stress need to be addressed and resolved by scientists and policymakers if we’re going to have a rational, evidence-based approach to the approval and use of medical marijuana. These issues include the following:
There are inconsistencies in how medical conditions are qualified for medical marijuana use within a state and between states. … Those differences reflect inconsistencies in evaluating and applying current evidence toward decision making about qualifying indications for medical marijuana use.
Unlike most FDA-approved drugs that typically have 1 or 2 active constituents, marijuana is a complex of more than 400 compounds. … Given that marijuana has so many constituents, the results of studies with individual cannabinoids (eg, THC or CBD) cannot be extrapolated to marijuana and vice versa. In addition, unlike FDA-approved medications that have a relatively uniform composition, the composition of cannabis preparations can vary substantially in its content of THC and CBD, such that precise dosing may be difficult.
While the acute adverse effects of marijuana are quite well known, the effects of repeated exposure, as would occur with medical marijuana, need further study. … There is also a small but definite risk of psychotic disorder associated with marijuana use, as well as a significant risk of symptom exacerbations and relapse in patients with an established psychotic disorder.
The interactions of marijuana with other drugs that may be concurrently prescribed for qualifying conditions need further study. There are claims that medical marijuana may allow patients to lower their opioid analgesic doses. However, the existing evidence does not support this contention.
“If the states’ initiative to legalize medical marijuana is merely a veiled step toward allowing access to recreational marijuana, then the medical community should be left out of the process, and instead marijuana should be decriminalized,” D’Souza and Ranganathan conclude. “Conversely, if the goal is to make marijuana available for medical purposes, then it is unclear why the approval process should be different from that used for other medications.”