Antiseizure medications (ASMs) are the mainstay for the treatment of seizure disorders. However, about one-third of people with epilepsy remain refractory to current ASMs. Cannabidiol (CBD) has recently been approved as ASM for three refractory epilepsy syndrome indications in children and adults. In this study, we evaluated the overall clinical potential of an oral CBD to treat refractory epilepsy in patients with Dravet syndrome (DS), Lennox-Gastaut syndrome (LGS), and tuberous sclerosis complex (TSC) through a systematic review and meta-analysis. A comprehensive search of databases was conducted, including randomized controlled trials (RCTs) assessing the effect of CBD in epilepsy patients. The review was conducted as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review focused on RCTs involving patients receiving highly purified oral CBD (Epidiolex, 10 to 50 mg/kg/day) for up to 16 weeks. A subgroup analysis by syndrome and CBD with or without concomitant clobazam was conducted. The key outcomes were reduction in seizure frequency, differences in 50% responder rates, adverse events, and interactions with clobazam as co-therapy. Odds ratio (OR) with 95% confidence interval (CI) were estimated. Of 1183 articles screened, we included 6 RCTs meeting our eligibility criteria. All studies were considered to have a low risk of bias. In the pooled analysis, CBD treatment was found to be more efficacious compared to placebo (OR = 2.45, 95% CI =1.81-3.32, p < 0.01). Subgroup analysis by syndrome demonstrated the odds of ≥50% reduction in seizures with CBD treatment in patients with DS (OR = 2.26, 95% CI:1.38-3.70), LGS (OR = 2.98, 95% CI:1.83-4.85) and TSC (OR = 1.99, 95% CI = 1.06-3.76). Compared with placebo, CBD was associated with increased adverse events (OR = 1.81, 95% CI = 1.33-2.46) such as diarrhea, somnolence, and sedation, and any serious adverse events (OR = 2.86, 95% CI = 1.63-5.05). Other factors, including dosage and clobazam co-therapy, were significantly associated with a greater effect on seizure control and side effects of CBD. In conclusion, the study shows that CBD is highly efficacious both as standalone and adjunct therapy with clobazam for controlling seizures in DS, LGS, and TSC conditions while limiting side effects. Further pharmacodynamic investigation of CBD actions, drug interaction assessments, and therapeutic management guidelines are warranted.
Keywords: CBD; Cannabidiol; Clobazam; Epilepsy syndrome; Pediatric epilepsy; Refractory seizures.
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