An experimental epilepsy drug made from cannabis plants grown in England is complicating the medical marijuana debate in hospitals and statehouses.

Epidiolex is a nearly pure extract of cannabidoil (CBD), with little of the tetrahydrocannabinol (THC) that gets users high. CBD products are highly sought-after medicinal pot products, and activists fear that if the maker of Epidiolex gets FDA approval, it could undercut the political momentum of the medical marijuana movement.

A pediatric neurologist who oversees Epidiolex’s clinical trials at Nationwide Children’s Hospital in Columbus, Ohio, Anup patel, insists the drug contains the optimal known marijuana compound for treating seizures. He cited a study that found using the whole plant can hurt children.

Patel laments that children with epilepsy are being using to push for medical marijuana legalization, including during an unsuccessful Ohio ballot campaign last year.

“People are mixing terms, mixing ideas,” he said. “I’m not sure if that’s just because of confusion, lack of knowledge or on purpose.”

Karmen Hanson, expert on marijuana policy for the nonpartisan National Conference of State Legislatures, said the two sides are at odds.

“The argument for traditional (whole-plant) medical marijuana is that people know what works for them — whether they’re going to make their own concentrates or vape or combust, use flowered products, oils, you name it — so they want to protect their ability to do that,” she said. “The other camp wants to see the head-to-head science, to give it more scientific validity, to elevate the products that are produced in terms of reliability and consistency.”

Patel is in Camp 2. He personally lobbied to get U.S. patients access to Epidiolex, which he said is effective, consistent and doesn’t get users high.

Roughly two years ago, Patel persuaded GW Pharmaceuticals, a London-based company, to give him enough of the medicine for a single patient, and his hospital’s study was born. Last month, the company release positive results of late-stage testing. It plans to take Epidiolex to the U.S. Food and Drug Administration later this year.

THE FDA has not yet found any botanical form of marijuana to be safe or effective to treat any disease or condition, according to spokesman Michael Felberbaum. If Epidiolex is approved it would be the first, however, there are two synthetic cannabinoids – Marinol and Cesamet – available.

An FDA approval would allow any doctor to prescribe Epidiolex to any patient, and it would be covered by insurane. No law or ballot issue would be required.

Many medical marijuana activists fear the approval of Epidiolex will mark the beginning of Big Pharma’s takeover of the marijuana plant, undercutting patients’ ability to treat themselves as they see fit.

“We are not concerned with the pill (actually oil) form of a natural plant,” said Wendy Johnson, who represents the Cannabis Safety Association in Ohio. “In fact, it is looked upon very unfavorably and as a stumbling block on our way to whole plant.”

Twenty-three states now have medical marijuana and cannabis programs – but 17 others have chosen to permit use of “low THC, high cannabidiol” products, mostly cannabis oils or hemp extracts.