Can medical marijuana treat epilepsy?

Medical marijuana has generated excitement in all corners of the medical community, from doctors and patients alike. It’s now legal for medical purposes in 23 states, and the State of Illinois Medical Cannabis Pilot Program approves its use for variety of conditions, including cancer, multiple sclerosis and Parkinson’s disease.

The strongest scientific evidence so far is that marijuana can be used to treat chronic pain stemming from these conditions and other injuries, which could provide a safer alternative to opioid painkillers. But highly publicized cases in Virginia and Colorado have stirred a grassroots push by families of children with severe forms of epilepsy like Dravet syndrome and Lennox-Gastaut syndrome to use cannabidiol oil and other compounds extracted from cannabis to treat seizures as well.

The anecdotal evidence that these compounds can treat epilepsy is promising, but the scientific data is still thin. The University of Chicago is currently participating in four clinical trials using such compounds for children with epilepsy, including a synthetic form of cannabidiol, to learn more about their safety and effectiveness.

Science Life spoke to Michael Kohrman, MD, Director of the Pediatric Epilepsy Program at the University of Chicago Medicine, about these trials, the promise of medical marijuana for treating epilepsy and whether the hype may have gotten ahead of the science.

How do these trials work in practice?

Michael Kohrman, MD

We’re using synthetic cannabidiol, which just means it was created in a lab as opposed to being extracted from the plant. It has exactly the same properties as the natural product. It’s a liquid, so it’s mixed in right now with oil administered orally twice a day.

Does cannabidiol have the same side effects as marijuana in general?

Most of the side effects we think about in marijuana are from THC. THC produces the high, it produces the hunger and it produces the sedation. Cannabidiol doesn’t have any euphoric properties to it. It tends to have mild stimulant effects, and it doesn’t have any appetite effects. There are very few other side effects to suggest significant downsides to the medicine to date, but that’s in a very small data set so far.

How does it work to help patients with epilepsy?

That’s the million-dollar question right now. All the data we have is from some animal work and one clinical trial in the 80s. There’s also a competing set of trials with 137 patients using a natural product that appears to be effective, about a 50 percent reduction of seizures in 50 percent of the patients. However, if we look at the most recent sets of double blind, placebo-controlled trials in the last 5 years, placebo rates were approaching 40 percent. So it’s hard to know what a 50 percent response rate is when you have 40 percent placebo response in other trials. So that’s why I say we don’t know whether it works or not.

Do you think it still has promise? This seems like a case where the hype has gotten ahead of the science.

That’s exactly correct, and it’s always a problem. That’s why we have clinical trials first. From my perspective I still think it’s important that patients work with physicians before they try it on their own, because you don’t want them making mistakes with their other drugs.

Is there something about these conditions that leads people to seek more unproven treatments?

If you look at epilepsy in general, we win 70 percent of the time. We’ll put you on medicine, we’ll stop your seizures and we’ll be able to get you off medicine. A third of the patients, however, have what we call refractory epilepsy. They fail two or more drugs, and those patients are often difficult to treat. So the first drug works 50 percent of the time, the second drug works 25 percent of the time. After that–and “working” in my parlance means a cure—they work only three to five percent of the time. Any time you try a new drug you’ve got about a 50/50 chance of cutting your seizures in half.

Marijuana Research

Cannabidiol oil is an extract from the cannabis plant, usually administered orally

So these patients, after trying five or six drugs, are desperate for something and they’ll try it because nothing else is working. All the drugs I normally prescribe have side effects, and marijuana has side effects too: It makes you hungry, it makes you sleepy and there may be some long-term cognitive issues that we talk about in some of the studies. But its perception in the lay community is a “safe” natural product. That’s why people are trying it, and that’s why the public support is there. That’s why the science is catching up with the public perception.

And it just may not be effective in this case …

At the end of the day, there’s also what’s known as the “entourage effect.” There are about 200 different chemicals in marijuana, so it may not be just the cannabidiol that’s effective, but it may be the cannabadiol plus this or that chemical too.  We think about THC and cannabidiol, but there are others as well. Whether this entourage effect exists or not is even more debatable. There’s a lot of folklore associated with it in the community, and we need to get some science behind it.

What’s a reasonable expectation for these trials?

I would like to see the drug more effective than a placebo, which means a 50 percent reduction of seizures in 30 to 50 percent of patients. At the end of the day, that’s what I want to see, with no significant side effects. I’d like to treat it like any other anti-convulsive medication that has FDA approval, because that’s the only way to handle any compound, and judge it just like we would judge anything else. Marijuana isn’t special. Cannabidiol is just another potential anti-convulsive for patients with epilepsy.

About Matt Wood (450 Articles)
Matt Wood is a senior science writer for the University of Chicago Medicine and editor of the Science Life blog.
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