The U.S. Food and Drug Administration approved a marijuana-based treatment for epilepsy Monday. The drug, called Epidiolex and developed by GW Pharmaceuticals Plc, is the first cannabis-derived medicine approved in the U.S. It will treat people suffering from Dravet Syndrome and Lennox-Gastaut Syndrome, difficult-to-treat forms of epilepsy. It is made from cannabidiol and contains less than 0.1 percent of marijuana’s psychoactive chemical, tetrahydrocannabinol (THC). “Advancing sound development programs that properly evaluate active ingredients contained in marijuana can lead to important medical therapies,” said Food and Drug Administration Commissioner Scott Gottlieb.