A powerful drug derived from marijuana is on the cusp of federal approval

• An experimental cannabis-derived drug faces a key vote on Thursday, when a group of scientists convened by the Food and Drug Administration will decide on its safety and effectiveness.
• The vote will play a key role in the FDA's final approval decision, which is scheduled for June.
• The drug, called Epidiolex, is made by GW Pharmaceuticals and is designed to treat two rare forms of epilepsy.

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An experimental drug derived from cannabis to treat epilepsy is on the brink of becoming the first of its kind to win US government approval.

On Thursday, a panel of outside experts convened by the Food and Drug Administration will vote on the drug's safety and effectiveness. Their recommendation will play a key role in the FDA's approval decision for the drug, which is made by GW Pharmaceuticals.

If the FDA gives final approval - a decision is expected in June - the new drug would be sold under the name Epidiolex as a syrup. It would be the first drug whose active ingredient is cannabidiol, the compound in marijuana thought to be responsible for many of its therapeutic effects. Cannabidiol doesn't contain THC, marijuana's main psychoactive ingredient, and is not linked with euphoria or the drug's characteristic high.

CBD appears to help reduce seizures, at least in two of the hardest-to-treat forms of epilepsy, known as Lennox-Gastaut Syndrome and Dravet Syndrome. That's according to two large clinical trials that the FDA considered on Tuesday, two days ahead of the vote. Based on those results, the scientists on the panel concluded that GW's submission "appears to support approval."

While Epidiolex would be the first cannabidiol-based drug to land FDA approval, the agency has already given the green light to other drugs that contain a lab-made version of THC. Currently sold under brand names Marinol and Syndros, the drugs are designed to treat some negative side effects of chemotherapy and AIDS, such as nausea, loss of appetite, and weight loss.

GW Pharma's long road to FDA approval

Because GW Pharmaceuticals was able to show that its product addresses a critical need, it was able to apply for a designation to fast-track the Food and Drug Administration's often protracted approval process.

One clinical trial of the drug looked at its effects in 225 young people with Lennox-Gastaut Syndrome. The researchers split the study participants into groups and gave them either a high dose of the drug, a low dose, or a placebo for 14 weeks. The results were presented at an American Academy of Neurology meeting last year, and showed that participants in the high-dose group saw their seizure occurrence drop by 42%. Those given the low dose saw a decrease of roughly 37%. By comparison, those given the placebo only saw a 17% reduction in seizure occurrence.

The second trial, the results of which were published in May 2017 in the New England Journal of Medicine, looked at 120 children with Dravet syndrome. Half were given the drug and half received a placebo. Forty-three percent of the participants given the drug saw their seizures reduced by half, and 5% stopped having seizures entirely. The group given the placebo saw barely any improvement.

The FDA vote and the future of cannabis-derived drugs

In its public meeting on Thursday, a panel of outside scientists convened by the FDA will decide if Epidiolex is safe and effective. Their vote is a recommendation that will be considered when the final decision on whether or not to approve the drug is made later this summer.

Epidiolex would be designed to treat only two types of epilepsy, so FDA approval would mean the drug would be prescribed for a small group of patients. But medical professionals could technically prescribe it "off-label" for other conditions as well. (The anesthetic ketamine, for example, may currently be prescribed this way for some hard-to-treat forms of depression.)

According to the Centers for Disease Control and Prevention, epilepsy affects more than 4.3 million Americans. Although GW Pharma's current drug only focuses on two rare types of the condition, the company has said that it is exploring treatments for various other forms of epilepsy as well. If this initial drug gets the green light, that approval will likely galvanize new research into other marijuana-based drugs.