FDA okays marijuana-based drug for seizures

United States health regulators on Monday approved the first prescription drug made from marijuana, a milestone that could spur more research into a drug that remains illegal under federal law, despite growing legalisation for recreational and medical use.

The Food and Drug Administration approved the medication, called Epidiolex, to treat two rare forms of epilepsy that begin in childhood. But it's not quite medical marijuana.

The strawberry-flavoured syrup is a purified form of a chemical ingredient found in the cannabis plant but not the one that gets users high. It's not yet clear why the ingredient, called cannabidiol, or CBD, reduces seizures in some people with epilepsy.

British drugmaker GW Pharmaceuticals studied the drug in more than 500 children and adults with hard-to-treat seizures, overcoming numerous legal hurdles that have long stymied research into cannabis.

FDA officials said that the drug reduced seizures when combined with older epilepsy drugs. The FDA has previously approved synthetic versions of another cannabis ingredient for medical use, including severe weight loss in patients with HIV.

Epidiolex is essentially a pharmaceutical-grade version CBD oil, which some parents already use to treat children with epilepsy. CBD is one of more than 100 chemicals found in marijuana. But it doesn't contain THC, the ingredient that gives marijuana its mind-altering effect.

Physicians say it's important to have a consistent, government-regulated version.

"I'm really happy we have a product that will be much cleaner and one that I know what it is," said Dr Ellaine Wirrell, director of the Mayo Clinic's programme for childhood epilepsy. "In the artisanal products, there's often a huge variation in doses from bottle to bottle, depending on where you get it."

Side effects with the drug include diarrhoea, vomiting, fatigue, and sleep problems.

A GW Pharmaceuticals spokeswoman said that the company would not immediately announce a price for the drug, which it expects to launch in the fall. Wall Street analysts have previously predicted it could cost US$25,000 per year, with annual sales eventually reaching US$1 billion.

For their part, GW Pharmaceuticals executives say they are not trying to disrupt products already on the market. The company has pushed legislation in several states to make sure its drug can be legally sold and prescribed.

The FDA approval for Epidiolex is technically limited to patients with Dravet and Lennox-Gastaut syndromes, two rare forms of epilepsy for which there are few treatments. But doctors will have the option to prescribe it for other uses.Before sales of Epidiolex can begin, the Drug Enforcement Administration must formally reclassify CBD into a different category of drugs that have federal medical approval.

GW Pharmaceuticals makes the drug in the United Kingdom from cannabis plants that are specially bred to contain high levels of CBD. And the company plans to continue importing the medicine, bypassing onerous US regulations on manufacturing restricted substance.