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Have we gotten ahead of the evidence with medical marijuana? Two doctors say yes

REUTERS/Eduardo Munoz
People using electronic vaporizers with cannabidiol (CBD)-rich hemp oil.

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.”

You’ll find abstracts for the editorial and the review article on JAMA’s website, but both, unfortunately, are behind a paywall.

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Comments (7)

  1. Submitted by Rachel Kahler on 07/01/2015 - 10:44 am.


    The arguments put forth by these two doctors are applicable to marijuana, not the individual compounds that are available for subscription in MN.

  2. Submitted by Ron Gotzman on 07/01/2015 - 11:07 am.

    Great Article

    I also think that it is interesting that the “anti-smoking” zealots are strangely silent when it comes to the smoking of weed.

    • Submitted by Pat Berg on 07/01/2015 - 03:11 pm.

      We’ve been over this before . . . . .

      So far, no one has lit up a joint while sitting next to me in a public place, in a restaurant, or at my place of employment.

      Until and unless that happens, there’s nothing to speak up about.

      • Submitted by Ron Gotzman on 07/01/2015 - 05:50 pm.

        Thanks for proving my point

        Public health includes the individual – not just how it effects you! Are you aware of the past 15 years and the campaign against smoking?

        • Submitted by Pat Berg on 07/02/2015 - 07:48 am.


          In what way have I proven your point?

          The laws regarding smoking have to do with smoking in public places or places of employment. This is because it is not fair to subject the individuals around you to the health risks of your secondhand smoke.

          Since marijuana is currently (mostly) illegal, it would make no sense to pass laws against smoking in public places or places of employment.

          If and when smoking marijuana becomes legal, we can then talk about those laws.

  3. Submitted by Greg Kapphahn on 07/01/2015 - 02:20 pm.

    “Refer Madness” Abides

    The questions this article poses would, long since, have been settled, or at least far more extensively researched,…

    if the paranoia among “conservatives” in our society had not meant that is has,…

    and CONTINUES to be,…

    illegal in most areas to possess and utilize the substances required to perform the needed research,…

    even in the kinds of controlled settings required by such research.

    Because of these issues, the 79 “research studies” cited in the editorial by Drs. D’Souza and Ranganathan have been very limited in scope and breadth, and have lacked the numbers of research subjects required to draw valid conclusions,…

    as such the negative results Drs. D’Souza and Ranganathan claim to have found are far more akin to “anecdotal evidence” than they are to being the clear results of definitive research.

    The jury is still out with respect to the effects of marijuana in its various forms,…

    but, given the current research environment,…

    and the desire of the Health Care industry in the US to maintain the profit margins provided by the very expensive pharmaceuticals and protocols they currently control,…

    far more easily and effectively than they could control marijuana if it came into more general usage,…

    it’s likely that that jury will STAY out for a very long time yet to come.

  4. Submitted by K. Knutson on 07/01/2015 - 04:19 pm.

    The Authors Have a Conflict of Interest That Should Be Disclosed

    The authors of the JAMA editorial receive big money from the pharmaceutical industry — a conflict of interest that should have been disclosed. According to ProPublica (another nonprofit news source, like MinnPost), Dr. Ranganthan is the largest beneficiary of pharmaceutical research dollars in the State of Connecticut. Dr. D’Souza is not far behind. That conflict of interest may explain their preference for “commercially available” versions of the active ingredients in medical marijuana.

    Additionally, unlike most FDA-approved drugs (to borrow the authors’ phrase), marijuana is grown in the earth, not in a lab, which means (1) of course it has more “constituents” than lab-made substances; (2) it offers little, if any, profit to the pharmaceutical industry; and (3) it is naturally less suspect given 2,000 years of real world experience. Should we not be more trusting of a medicine made by god/nature than one made by a man in a lab coat with dollar signs in his eyes?

    The lack of conclusive research on medical marijuana is hardly surprising given legal limitations on that research and the lack of funding for it. The government generally does not fund such research, and the pharmaceutical industry has no more incentive to fund research on marijuana than it does spinach or kale. You cannot withhold a paintbrush and then complain about the lack of a portrait.

    Thank goodness Dr. Farber did not wait for conclusive research before exploring chemotherapy as a possible cure for children’s leukemia — a cure sought for sake of humanity, not profit, no less. We can only hope that the well-funded psychiatrists at Yale are so motivated.

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