Add-on cannabidiol induces sustained seizure reduction in treatment-resistant epilepsy

Patients with treatment-resistant epilepsy appear to benefit from add-on cannabidiol (CBD), which a recent study has shown to help reduce seizure frequency for up to 192 weeks.

A total of 892 patients (median age 11.8 years) received plant-derived highly purified CBD (100 mg/ml oral solution), given at a starting dose of 2–10 mg/kg/day then increased to tolerance or maximum dose of 25–50 mg/kg/day, depending on the study site.

Researchers evaluated outcomes including the change in median monthly convulsive and total seizure frequency and ≥50-percent, ≥75-percent, and 100-percent responder rates across 12-week visit windows for up to 192 weeks. They also recorded adverse events (AEs) at each visit.

At baseline, the patients were taking a median of three antiseizure medications at baseline, with the most common being clobazam (47 percent), levetiracetam (34 percent), and valproate (28 percent). A total of 322 (36 percent) patients discontinued CBD treatment due to lack of efficacy (19 percent) or AEs (7 percent). Median top CBD dose was 25 mg/kg/day, and median exposure duration was 694 days.

Treatment with CBD reduced monthly convulsive seizures by 50–67 percent and total seizures by 46–66 percent. Convulsive seizure responder rates (≥50-percent, ≥75-percent, and 100-percent reduction) ranged 51–59 percent, 33–42 percent, and 11–17 percent across visit windows, respectively.

A total of 88 percent of patients experienced AEs, and 41 percent had serious AEs. Twenty cases of deaths were documented during the study, with the cause of death deemed unrelated to treatment. The most frequent AEs (≥20 percent of patients) were diarrhoea (33 percent), seizure (24 percent), and somnolence (23 percent).