Rarely a week goes by without a patient asking about marijuana and its medicinal use.

In the last two decades, there has been a wide shift in public opinion in regard to marijuana and its potential healing properties. Marijuana has been touted as a treatment for everything from glaucoma to epilepsy to chronic pain.

Thirty-one states have now legalized marijuana for medical use in one form or another. On the upcoming ballot this November, voters will be asked whether Missouri should become a state that allows the prescribing of marijuana for medicinal purposes.

Unfortunately, few of the medicinal claims about marijuana have been supported by robust clinical trials. Indeed, research has been hampered by the scheduling of marijuana by the FDA, which has prevented many of the large trials that pharmaceuticals typically undergo prior to approval as a medication.

The clinical studies that have been done are small and stand alongside mostly anecdotal evidence. For many physicians in Missouri this paucity of data creates concern that we might be placing the cart before the horse – or more literally approving a drug before there is adequate evidence of its risks and benefits.

When I prescribe a medication, I have research data about bioavailability, dosing, side effects and drug interactions. Little of that is currently available for marijuana. There is much heterogeneity in marijuana plants, which creates confusion about the actual dose a patient may receive.

Further, patients choose a range of ways to take in marijuana — most commonly smoking or ingestion — and in many forms. While smoking has been shown to be superior in the delivery of cannabinoids, it holds its own risk of lung injury and a concern for cancer. There is not clear data about cooking marijuana, and dose would be contingent on how it was cooked, other ingredients, and at what temperature.

Pharmaceuticals in the United States undergo stringent quality control to ensure patients receive pure substance and doses in each pill, inhalant or injection they take. It is not clear that all medical marijuana goes through the same rigorous testing. Marijuana contains over 60 cannabinoids, which are the pharmacologically active chemicals attributed with the analgesic and neuroactive properties of the plant.

There are many more chemicals (at least 400 based on some data) in the plant. There is not clear data on what these other chemicals may or may not do and how heating changes their properties. Of the quality evidence that is available, most are on pharmaceutical grade cannabinoid derivatives, such as dronabinol and nabilone, rather than plant-based marijuana.

Other questions include: Which patients can it be prescribed to and for what indications. Many states that allow medical marijuana expand the indication list much beyond what there is evidence for. This can create a circus where the medical use of marijuana blurs into recreational use.

This is evidenced by the way that medical marijuana is portrayed in the media — many comedians joke that anyone can get it for anything. Also, at what age can patients be prescribed marijuana? There is evidence to suggest that regular use of marijuana negatively affects brain structure, even in patients in their early 20s. Will we age restrict it?

I want to end by saying that I am not against reforming marijuana laws. In fact, I think a best-case scenario would be decriminalization and possibly even legalization recreationally so individuals have the freedom to decide whether to use it for health purposes.

I am also hopeful that as we learn more about marijuana and its contents, we may find many chemicals with properties for analgesia and reduction in inflammation (early evidence points to this). My concern about the ballot initiatives is asking doctors to prescribe something medicinally without full knowledge of adverse effects, drug interactions, and even interactions with medical co-morbidities. Medical history is littered with medications we once thought were beneficial and subsequently found to have substantial risk of harm (opioids being one recent example). Many of these medications had been studied much more extensively than marijuana.

As a physician I am tasked with avoiding harm above all else. I personally feel that if we are to prescribe something as a medication we should have clear evidence as to how and why it should be used — we should hold pharmaceuticals to the highest standard. This election season Missourians should think about the risks and benefits of medical marijuana to be able to make an informed vote on whether medical marijuana is right for our state.

In my mind, the research just doesn’t support promoting marijuana as a medication.

Nathanial Nolan is a third-year internal medicine resident at the University of Missouri. Along with his M.D .he completed a master’s degree in public health.

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