Effectiveness and safety of cannabidiol in adult patients with epilepsy: A multicenter, retrospective study.

Sánchez-Gamino S.; Chamorro Muñoz M.; Serrano-Castro P.; Hernández-Vitorique P.; Rodríguez Jiménez L.; López Moreno Y.; Cabezudo-García P.; García Martín G. · Epilepsia open · 2026

**Background & Methods** This multicenter, retrospective observational study evaluated the effectiveness and safety of cannabidiol (CBD) as adjunctive treatment in 37 adults (median age 25 years; 67.5% male) with drug-resistant developmental and epileptic encephalopathies, specifically Dravet syndrome, Lennox-Gastaut syndrome, or tuberous sclerosis complex, who received CBD for at least 12 months. Medical records were reviewed to assess baseline characteristics, treatment retention, seizure frequency, cognitive-behavioral improvements, concomitant antiseizure medication (ASM) usage, and adverse events over a median follow-up period of 28 months. **Key Findings** • Seizure frequency was reduced by ≥50% in 48.6% of patients at 6 months and 45.9% at 12 months, demonstrating clinically meaningful efficacy comparable to pediatric cohorts. • CBD treatment was significantly associated with reduction in concomitant ASM burden, with median number of concomitant medications decreasing from 4 to 3 (p = 0.022), potentially reducing polypharmacy-related complications. • Subjective improvements in cognition and behavior were reported by caregivers in 29.7% of patients, suggesting potential benefits beyond seizure control. **Dosage & Administration** Median CBD maintenance dose was 10.45 mg/kg/day (interquartile range 7.455-13.975 mg/kg/day), with median maximum dose of 11 mg/kg/day. No statistically significant differences in maintenance doses were observed across seizure reduction categories. **Safety & Adverse Effects** Adverse events occurred in 64.9% of patients and were predominantly mild in severity. Treatment discontinuation due to adverse events occurred in 16.2% of patients. Specific adverse event types were not detailed in the abstract. **Evidence Quality** This retrospective observational study is limited by its small sample size (n=37), lack of control group, and retrospective design, reducing ability to establish causality or control for confounding variables. The reliance on medical record review and caregiver-reported subjective improvements (cognition) introduces potential reporting bias. As acknowledged by the authors, prospective randomized controlled trials are needed to better define CBD's independent treatment effect and establish more rigorous safety profiles in adult populations with complex developmental and epileptic encephalopathies. The findings provide valuable real-world evidence but represent level 4 evidence in the hierarchy of clinical evidence.

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