A recent review article draws from existing clinical trials and clinical experience in New South Wales, Australia, to fill this gap with interim guidance for both pediatric and adult patients. The article was published in the British Journal of Clinical Pharmacology.
The only current U.S. guidelines are from the American Academy of Neurology’s position statement on the use of medical cannabis for neurologic disorders and the American Epilepsy Society’s position statement on cannabis as a treatment for epileptic seizures. The AAN statement “highlights the current evidence, which currently only supports [Food and Drug Administration]–approved CBD [cannabidiol] (Epidiolex) for specific epilepsy syndromes,” said Daniel Freedman, DO, an assistant professor of neurology at the University of Texas at Austin and coauthor of the AAN’s position statement.
“Rescheduling marijuana will enable researchers to study CBD, THC [tetrahydrocannabinol], and other cannabinoids in high-quality studies so that we can better understand what works and for which conditions,” said Dr. Freedman, who was not involved in the Australian guidance document. He noted that little consensus exists because little evidence exists outside the handful of trials for Epidiolex.
“There are some patients with epilepsy that can benefit from high-quality, pharmaceutical-grade CBD products,” Dr. Freedman said. “These patients need to be carefully identified by a neurologist or epileptologist and prescribed a legal, safe, quality-controlled, and FDA-regulated product.”
Appropriate patient populations
Drug-resistant epilepsy, defined as failure of two appropriate antiseizure medications, affects an estimated one third of people with epilepsy, the new guideline notes. Though many over-the-counter products are available at dispensaries in the 33 U.S. states that allow use of cannabis for medical purposes, Epidiolex (cannabidiol) is the only FDA-approved drug for epilepsy that contains a substance derived from cannabis and the only one for which evidence from randomized, controlled trials exists.
Dr. Freedman notes that hemp-derived CBD oils are classified differently in the United States than marijuana-derived CBD oil, including Epidiolex, and are loosely regulated supplements or food additives commonly seen, for example at gas station.
“The point I drive home to patients is that you wouldn’t get your antibiotics from a gas station, so please don’t get your seizure medication from there,” Dr. Freedman said. “Studies have been done on ‘over-the-counter’ CBD oils and shown that they have variable quality, sometimes no detectable CBD, and sometimes other chemicals added like THC.”
Studies of Epidiolex showed that cannabidiol more effectively reduced seizure frequency than placebo for pediatric patients with Dravet syndrome (42% reduction) and for pediatric and adult patients with Lennox-Gastaut syndrome (39% reduction) or tuberous sclerosis complex (49% reduction). Efficacy was similar across dosing from 10-50 mg/kg per day, but higher doses involved higher rates of serious adverse events.
No reliable evidence in humans exists for THC or other cannabinoids in treating epilepsy.
The Australian guidance recommends limiting cannabis treatment to patients with severe drug-resistant epilepsy; a diagnosis of Dravet syndrome, Lennox-Gastaut syndrome, or tuberous sclerosis complex; and previous treatment with four approved antiseizure medications and/or the ketogenic diet, epilepsy surgery, or neurostimulator. The authors provide specific criteria for each of these conditions and then address exceptional cases that may be considered outside that criteria, such as patients under 2 years old, severe epilepsy with extended or repeated hospitalization or ICU admission, or a dangerous seizure type. The review also includes a detailed list of exclusion criteria for CBD medicine use.
The authors advised a thorough consent process before prescribing any cannabinoids, including therapeutic goals and stopping criteria; the lack of evidence available on dosing, efficacy, and side effects; and the potential for dependence or withdrawal. Consent discussions should also note whether the products are unregistered and not covered by external payers (anything other than Epidiolex currently), any activity restrictions, and any implications for occupational drug screening.