Research Article| Volume 112, 107474, November 2020

Long-term efficacy and safety of cannabidiol (CBD) in children with treatment-resistant epilepsy: Results from a state-based expanded access program

Published:September 26, 2020DOI:


      • Children with treatment-resistant epilepsy received increasing doses of cannabidiol.
      • Incidence of all and major seizures was significantly reduced over 36 months.
      • Mean increase in seizure-free days was >5 in each 28-day treatment period.
      • Cannabidiol was generally well tolerated in doses up to 50 mg/kg/day.



      An intermediate-sized, multicenter, expanded-access study was opened in 2015 through the support of the State of Georgia. This study provided children with treatment-resistant epilepsy (TRE) access to plant-derived highly purified cannabidiol (CBD; Epidiolex® in the US; Epidyolex® in the EU; 100 mg/mL oral solution). These children had failed to achieve seizure freedom with available treatment options and were ineligible to participate in randomized controlled trials that only included patients with Lennox–Gastaut and Dravet syndromes.


      Cannabidiol safety, changes in seizure type, frequency, and seizure-free days were evaluated for children aged 1–18 years (at time of consent) as an adjunctive treatment for 36 months. The study consisted of a two-month baseline period, a titration period, treatment period, and optional titration period, which occurred after ≥26 weeks of treatment. Cannabidiol treatment was administered up to a targeted dose of 25 mg/kg/day, with an optional secondary treatment up to 50 mg/kg/day. Daily seizure type, seizure frequency, and seizure-free days were recorded in a Web-based diary, and changes in these outcomes were recorded and analyzed for the duration of the study. The occurrence of adverse events (AEs) was also recorded.


      The median percentage change in seizures for 45 patients in Months 3, 6, 12, 18, 24, and 36 showed a statistically significant (p < 0.001) reduction in major seizures (ranging from 54 to 72% at various time points) and all seizures (61–70%) compared with baseline. A mean increase in seizure-free days per 28 days was >5 in all treatment periods after Month 2, and an average increase of 7.52 (p < 0.001) seizure-free days per 28 days was observed at the end of follow-up compared with baseline. All patients experienced ≥1 AE. Children who transitioned to the optional secondary treatment (high-dose group) reported more AEs before increasing their dose to >25.0 mg/kg/day compared with the low-dose group. However, the average rate of AEs was significantly lower after moving to a high-dose regimen (p = 0.004). Twelve children reported 20 serious AEs, none of which were considered related to CBD.


      This study supports CBD as an adjunctive treatment for children with TRE. Treatment was well tolerated in doses up to 50 mg/kg/day. Patients who did not achieve desired results at a dose of ≤25.0 mg/kg/day reported more AEs when CBD dose increased to >25.0 mg/kg/day. Decreases in major seizure frequency and an increase in seizure-free days compared with baseline were reported during treatment. This supports the efficacy and tolerability of CBD for mixed seizure etiologies.


      AED (antiepileptic drug), CBD (cannabidiol), TESAE (treatment-emergent serious adverse event), TEAE (treatment-emergent adverse event), TRE (treatment-resistant epilepsy)


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