EFFICACY OF CANNABIDIOL IN DRUG-RESISTANT EPILEPSY: A SCOPING REVIEW ON SEIZURE REDUCTION COMPARED TO PLACEBO AND COMBINED PHARMACOTHERAPY

Abstract

Introduction: Refractory epilepsy poses a clinical challenge due to resistance to multiple antiepileptic drugs, adversely affecting seizure control and quality of life. In this context, cannabidiol (CBD) has emerged as an adjunct therapeutic option.
Objective: To evaluate the efficacy of CBD in reducing seizures in refractory epilepsy patients, comparing its effect against placebo and combined pharmacological treatments.
Methods: A systematic review was conducted in PubMed, ScienceDirect, Scopus, and Web of Science using specific keywords such as “Cannabinoids” and “Drug-Resistant Epilepsy.” Study selection involved independent screening and application of inclusion criteria prior to critical appraisal, data extraction, and risk of bias assessment.
Results: From 2,909 identified articles, 26 studies were included with follow-up ranging from 10 weeks to 3 years. CBD dosages varied across populations; generalized tonic-clonic seizures were the most prevalent (66%). All patients received concomitant antiepileptic therapy. Adjunctive CBD reduced seizure frequency by 28% at 14 weeks and up to 75% at 7 months. In Lennox-Gastaut syndrome, the mean monthly seizure reduction was 36.5%. In Dravet syndrome, CBD modulated intracellular calcium via GPR55 receptors and VDAC1 channels, decreasing neuronal excitability. Reported adverse effects included somnolence, anorexia, and diarrhea in 5% of patients.
Conclusions: CBD demonstrated efficacy in refractory epilepsy, particularly at doses of 25–50 mg/kg/day, with a favorable safety profile, representing a therapeutic alternative in cases resistant to conventional treatments.