People with a rare and more severe form of epilepsy called Dravet syndrome experienced significant decrease in seizures after taking cannabis-based drug Epidiolex.
In 2018, the U.S. Food and Drug Administration approved Epidiolex for the treatment of Dravet and Lennox-Gastaut syndromes in children above age 2. It is the first time that the agency approved a drug made from purified marijuana substance as well as the first treatment for Dravet syndrome.
Results of the phase 3 clinical trial showed that a lower dose of 10 milligrams per kilogram of body weight taken daily has the same efficacy as the 20-milligram dose. The only difference of the new trial from the 2017 paper published in the New England Journal of Medicine is the dosing.
A total of 199 children with Dravet syndrome took the drug infused with cannabidiol, a non-psychoactive compound found in cannabis. Within 14 weeks, the 20-milligram group had 47 percent fewer seizures and 46 percent fewer seizures with convulsions.
The group with only 10 milligrams of Epidiolex had 56 percent fewer seizures and 49 percent fewer seizures with convulsions. Seizure frequency in the placebo group decreased by 30 percent, while seizures with convulsions dropped by 27 percent.
"I personally was surprised to see such a robust treatment effect of the lower dose," said co-author Dr. Ian Miller of Nicklaus Children's Hospital in Miami, Florida. "Side effects are less frequent at the lower dose, and this study justifies trying patients on the lower dose first, to assess efficacy and tolerance."
Miller said increasing the dose to more than 10 milligrams per kilogram per day should be carefully evaluated for effectiveness and safety for each patient. The cannabidiol drug caused poor appetite, fever, diarrhea, and fatigue to about 7 percent of the participants.
Both doses of CBD are found to have almost the same efficacy, but the new study showed that a lower dose of CBD is better tolerated. However, an Israeli study that followed 92 children and adults with different forms of epilepsy found that the benefits of Epidiolex appeared to taper over time.
Researchers noted that about one-third of the patients experienced drug tolerance after an average of seven months. Doctors needed to increase the dosage to 30 percent to achieve the same reduced seizure effect.
The FDA approval means that patients in all states would have legal access to the drug. They can also request insurance coverage for the medication. Miller and his colleagues will present the details of the phase 3 clinical trial at the American Epilepsy Society's annual meeting in December.