An expert panel on Thursday unanimously recommended that the Food and Drug Administration approve a new medicine for two rare and devastating forms of epilepsy, paving the way for the authorization of what would be the country’s first medication made from marijuana.

The 13-0 vote from the FDA advisory committee is not binding, and the agency is expected to announce its decision by the end of June. But in documents this week, FDA officials wrote they supported the approval of the drug, Epidiolex, after concluding that it cut the number of seizures in patients in clinical trials.

“This is clearly a breakthrough drug for an awful disease,” said Dr. John Mendelson, a panel member and senior research scientist at Friends Research Institute.

Epidiolex, which is given as an oral solution, consists of cannabidiol, or CBD, a component of cannabis that does not make people high. Its manufacturer, GW Pharmaceuticals, is seeking its approval to treat Lennox-Gastaut and Dravet syndromes, two conditions that typically emerge in the first few years of life. Patients suffer from severe seizures, and an estimated 20 percent of patients die by the time they are 20 years old.

In trials, patients taking Epidiolex saw their monthly seizures reduced by about 40 percent.

Some patients in the trials experienced sleepiness or gastrointestinal issues, and the medication did not work for all patients. There is also some concern about the effect of the drug on the liver. In the briefing documents, the FDA officials wrote that the “risk of liver injury has the potential to be serious,” but that it could be addressed by tracking liver function during treatment.

Panelists said they were swayed by robust efficacy data from three clinical trials and that clinicians could easily handle any worries about side effects.

“The safety concerns could be managed with labeling and monitoring,” said Jane Acri, a panel member who works in medication development at the National Institute on Drug Abuse.

In sometimes emotional testimony, the parents of children with the conditions urged the panel and FDA to get the drug to the market. They described how they have to watch their children constantly, and the horror of their children’s seizures, which can be so violent they break bones. They explained the developmental setbacks their children faced and the problems with other medications and therapies they had tried.

“She couldn’t go outside, she couldn’t do anything that other kids do,” said Stephen Carlin, who showed videos of his daughter, Zora, who has Dravet syndrome, having seizures.

But after receiving Epidiolex, “her seizures went from 40 to 50 a day to only a few or none per week,” said Carlin, whose travel was paid for by GW.

Some families have moved to states where marijuana is legal either recreationally or medically to obtain CBD oil for their children’s epilepsy, and some states have changed their laws to make CBD oil available. But experts have said that having an approved and regulated medication available in a standard dose is important because self-treating can expose patients to irregular doses, substandard supplies, or the risk of side effects without medical oversight.

Evelyn Nussenbaum, the mother of a child with epilepsy, told the panel that she had tried to buy CBD from retailers, but that when she had it tested, she found out that many of them had lower concentrations of CBD than on the label, and some had none at all.

The Drug Enforcement Administration continues to classify marijuana as a Schedule I drug, meaning it has no proven medical value and a high risk of abuse. If Epidiolex is approved, the DEA will then have to reschedule cannabidiol—given that FDA approval demonstrates a medical value—but can leave cannabis overall at Schedule 1.

The FDA has previously approved synthetic medications—including Marinol and Cesamet—that resemble or are identical to THC, the component of marijuana that makes people high. The drugs, which are approved to treat nausea from chemotherapy and other conditions, are listed at Schedule III and Schedule II, respectively.

Epidiolex comes from a proprietary strain of cannabis grown by GW that has been bred to have high levels of CBD and low levels of THC.

Analysts had expected a positive advisory committee recommendation, and they also expect the drug to be prescribed off-label for other types of epilepsy if it is approved. Ahead of Thursday’s advisory committee review, shares of GW Pharma were up about 7 percent this week.

There are six other drugs approved to treat seizures associated with Lennox-Gastaut, but none approved for Dravet.

Republished with permission from STAT. This article originally appeared on April 19, 2018