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.

The drug's 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, so it doesn't get users high.

According to results from two large clinical trials released over the past two months, however, cannabidiol does appear to help reduce seizures in two of the hardest-to-treat forms of epilepsy, Lennox-Gastaut Syndrome and Dravet Syndrome.

If approved, the new drug would be sold under the name Epidiolex as a syrup.

Because drugmaker GW Pharma was able to show that the product addresses a critical need, it was able to apply for a designation that could speed up the approval process. The company still faces some hurdles, though — the FDA has not yet approved any applications to sell marijuana for a health condition, and hasn't given the green light to any drugs containing cannabidiol.

The first cannabidiol trial looked at the effects of the drug by studying 225 young people with Lennox-Gastaut Syndrome. The subjects were split into groups and given either a higher or lower dose of the drug or a placebo for 14 weeks. The results, presented at the American Academy of Neurology's yearly meeting in Boston, showed that participants in the higher-dose group saw their seizure occurrence drop by about 42%. Those given the lower dose saw a decrease of roughly 37%, and those given the placebo only saw a 17% reduction.

The second trial, the results of which were published this week 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 participants given the drug saw their seizures reduced by half, and 5% stopped having seizures entirely. By comparison, the seizure rate in the group given a placebo barely budged.

Those promising findings build on previous research conducted last year by GW Pharma.

According to the Centers for Disease Control and Prevention, epilepsy affects more than 4.3 million Americans. Among these millions, however, various types and forms of the condition exist — and everyone reacts to treatments differently.

GW Pharma aims to submit its new drug application to the FDA by the middle of the year, and is exploring treatments for various forms of epilepsy, though Epidiolex would treat only two specific types of the condition.

While Epidiolex could be the first cannabidiol-based drug to get FDA approval, the agency has already given the green light to two other drugs that contain components of cannabis: Marinol and Syndros are designed to treat anorexia using dronabinol, a synthetic form of THC.