For adults with drug-resistant focal epilepsy, no difference in efficacy was observed at 12 weeks for adjunctive therapy with transdermal cannabidiol (CBD) versus placebo, according to a study published in JAMA Network Open. Terence J. O’Brien, MD, and colleagues examined the efficacy, safety, and tolerability of transdermal CBD in adults with drug-resistant focal epilepsy receiving a stable regimen of antiseizure medications. A total of 188 patients were randomly assigned to 195 mg or 390 mg transdermal CBD or placebo (63, 62, and 63 participants, respectively) for 12 weeks, after which they could enroll in an open-label extension study. At week 12 of the double-blind period, no difference was seen in seizure frequency between placebo and either CBD dose (mean, 2.49, 2.51, and 2.59 seizures per 28 days, respectively). Overall, 60.8% of patients achieved a seizure reduction of at least 50% by month 6 of the open-label extension. Treatment-emergent adverse events were similar in the CBD groups. “Additional randomized, well-controlled clinical trials using higher doses of transdermal cannabidiol in this patient population appear to be warranted,” Dr. O’Brien and colleagues wrote.