A drug called Epidiolex recently became the first marijuana-derived drug to win federal approval.

On Thursday, the drug became officially available with a doctor's prescription following a required move from the Drug Enforcement Agency.

The CEO of GW Pharmaceuticals, the company behind the drug, said he plans to focus on getting federal approval for another drug called Sativex next.

While Epidiolex contains CBD (a marijuana compound not responsible for a high), Sativex contains THC (which does cause a high).

It's been a busy few months for Justin Gover, the CEO of a pharmaceutical company that makes the first marijuana-derived drug to win federal approval.

After being green-lit by the Food and Drug Administration in June, the drug — called Epidiolex — awaited a final sign-off from the Drug Enforcement Agency before it could be prescribed by doctors for the treatment of two rare forms of epilepsy. And on Thursday, the agency officially cleared it by placing any FDA-approved drug containing CBD, a compound in cannabis not linked with a high, into Schedule 5. (Schedule 5 drugs are those considered to have the lowest abuse potential and include drugs like cough syrups made with codeine.)

Now that Gover has passed one hurdle, the CEO of GW Pharmaceuticals is onto the next.

He aims for Sativex — another drug in his company's pipeline — to become the second federally-approved drug derived from the marijuana plant. But unlike Epidiolex, whose only active ingredient is the non-psychoactive compound CBD, Sativex also contains THC, the marijuana compound that does cause a high.

If approved, it would be the first federally-approved marijuana derived medication made with THC from the cannabis plant.

Sativex is currently available in 30 countries outside the US for the treatment of multiple sclerosis and pain. But as Gover explained to Business Insider, GW Pharmaceuticals "never engaged with the FDA to get it approved in the US."

Now that Epidiolex has been given the all-clear, Gover is moving ahead with Sativex.

"We now plan to meet with the FDA and determine a path forward," he told Business Insider.

One other THC-containing drug has been approved by the US government: AbbVie's Marinol, which treats nausea, vomiting, and a lack of appetite caused by treatments for cancer and AIDS. But it contains a synthetic or lab-produced version of THC, not the kind found in the whole plant.

Sativex is "a very late-stage opportunity for which we’ve generated a lot of data," Gover said. "And it has a lot of potential, both for MS and neuropathic pain and potentially for other neurological conditions as well."