An advisory panel to the U.S. Food and Drug Administration has unanimously recommended approval of an epilepsy drug, the first prescription medicine in the United States containing cannabidiol.

The FDA voted in June to approve the drug, Epidiolex, an oral solution to treat severe forms of epilepsy in a small group of patients. The FDA has also approved synthetic versions of some chemical cannabinoids found in the marijuana plant, for other uses that include pain relief for cancer patients.

Cannabidiol, also called CBD, is one of more than 80 active cannabinoid chemicals, but unlike tetrahydrocannabinol, or THC, it has no psychoactive effects.

The committee's recommendation was made after a review of data from the drug's manufacturer, GW Pharmaceuticals PLC, a British biopharmaceutical company.

“We are obviously very pleased with the unanimous recommendation to support the approval of Epidiolex,” said GW CEO Justin Gover. “It is a very important step in the approval process.”

Epidiolex, GW's lead cannabinoid product candidate, was developed for severe, early-onset epilepsy syndromes , including Dravet syndrome, a rare genetic brain dysfunction that begins in early life; Lennox-Gastaut syndrome, a type of epilepsy with several types of seizures; and tuberous sclerosis complex and infantile spasms, both of which begin in childhood and cause a sudden stiffening of the body, arms, and legs, with the head bowed forward.

One-third of Americans who suffer from epilepsy have not found therapies that can control their seizures, according to the Epilepsy Foundation . This is about one million families. Although the FDA approval limits the drug's use to epilepsy patients, doctors would have the option to prescribe it “off-label” for other uses.

Shauna Garris, a pharmacist, clinical pharmacology specialist and associate professor at the University of North Carolina Eshelman School of Pharmacy, said she would have been surprised if Epidiolex had not received full FDA approval. Garris was not involved in the development of the drug and has never used it in her clinical practice.

However, she said, "there's so much hype and so much hype" around the product, that she's not sure it can live up to "all that hype."

Epidiolex is effective, he said, and works “somewhat” to “very” well.

“There have been side effects associated with the drug, and many of them have occurred in conjunction with other medications, which is a concern because most patients also take other medications,” Garris said. There will likely be drug interactions, he said, but "that's not uncommon for antiepileptic drugs."

“Most of our antiepileptic drugs have terrible side effects and interact with each other,” he said. However, this may have an impact on its potential effectiveness.

In a statement, GW Pharmaceuticals said that two experimental clinical trials, one for Dravet syndrome and one for Lennox-Gastaut syndrome, showed "significantly greater reductions" in certain types of seizures for patients taking the drug. 'Epidiolex, compared to those taking a placebo.

During the public hearing of the advisory committee meeting, 16-year-old Sam Vogelstein, of Berkeley, California, described himself as "the first person to try Epidiolex for epilepsy." He said he was not paid by the company for his speech.

“I had seizures for 10 years,” he said. “My parents told me there were times I had seizures 100 times a day.” He started taking Epidiolex five years ago. “I haven't had attacks for more than two years now. It changed my life .”

Damage to the liver, which metabolizes drugs and removes toxins from chemical elements, is an important thing to take into account in the process of recommending any medicine.

Dr. Lara Dimick-Santos, a clinical reviewer in the FDA's Office of Drug Evaluation, reviewed the liver safety report and concluded that there were "no cases of serious liver injury" and "no death linked to liver damage”. He suggested, however, that some patients may experience a form of “unknown chronic liver damage.” Such an “intense inflammatory response” could “potentially cause a problem for patients in the long run.”

Katherine Bonson, a staff member of the FDA's Pharmacologist Controlled Substance, established the abuse potential of cannabidiol after looking at data from experiments on both animals and humans. “The overall conclusion is that the preclinical data provide no indication that CBD has abuse potential,” he said.

Although the FDA stressed that its review of Epidiolex will be ongoing, Gover said he felt confident about the positive result. “It's a breakthrough in the field of epilepsy,” he said. “It is the first cannabis-based drug to be approved by the FDA. It is the first in a new class of treatments with a new mechanism of action against epilepsy.”