CBD-Rich Cannabis Oil Reduced Seizures by 84% in Adults With Drug-Resistant Focal Epilepsy | Research

The takeaway

An open-label study of 44 adults with drug-resistant focal epilepsy found that a CBD-rich, low-THC cannabis formulation reduced median monthly seizures from 11 to 2.5, with nearly 80% of patients achieving a 50%+ reduction at 12 weeks.

Adults with drug-resistant epilepsy, neurologists, medical cannabis patients with seizure disorders.

84% median seizure reduction; 80% of patients responded at 12 weeks

What the researchers found

Among 44 patients who completed 3+ months of follow-up, median monthly seizures dropped from 11 to 2.5 (p < significant). At 12 weeks, 79.5% achieved 50%+ seizure reduction, and the median percentage change in seizure frequency was 84.1%. Only five patients reported adverse drug reactions. The median daily dose was 200mg CBD / 4mg THC (3.7 mg CBD/kg).

Why it matters

Most CBD epilepsy research has focused on children and on specific syndromes like Lennox-Gastaut and Dravet. This study extends the evidence to adult drug-resistant focal epilepsy, a common form of epilepsy, showing striking response rates with a CBD-dominant formulation.

The numbers in context

44 patients completed 3+ months. Median seizures: 11/month before, 2.5/month after. 79.5% achieved 50%+ reduction at 12 weeks. 84.1% median seizure frequency reduction. Dose: 200mg CBD/day, 4mg THC/day, 3.7 mg/kg CBD. Only 5 adverse reactions.

How the study worked

Open-label, prospective cohort, single-center study of adults with drug-resistant focal epilepsy on stable antiepileptic drugs. Added a cannabis-based magistral formulation (100mg/mL CBD, <2mg/mL THC). Follow-up from August 2020 to July 2022.

What this study cannot tell us

Open-label, single-center study without placebo control. Only 44 of 114 enrolled patients completed 3+ months, introducing selection bias. No blinding means expectation effects may contribute to results. The formulation includes some THC, making it hard to attribute all effects to CBD.

How to read the evidence

Open-label prospective study with impressive effect sizes but no placebo control or blinding, meaning results need confirmation in randomized trials.

When this study was published

Published 2023, with data from 2020-2022.

The bigger picture

The 79.5% responder rate is remarkably high for drug-resistant epilepsy, where 50%+ reduction with any new treatment is typically achieved in only 20-40% of patients. While the open-label design means placebo effects and expectation bias could inflate results, the magnitude of effect warrants controlled trials in this population.

Questions still open

Would these results hold in a placebo-controlled trial?
What is the role of the small amount of THC in this formulation?

Common questions

Can CBD help adults with drug-resistant epilepsy?

This study found that a CBD-rich cannabis formulation reduced seizures by 84% in adults with drug-resistant focal epilepsy, with nearly 80% of patients responding. However, it lacked a placebo control.

What dose of CBD was used?

The median daily dose was 200mg CBD (3.7 mg/kg) with a small amount of THC (4mg/day).

Read the original research

Cannabis-based magistral formulation is highly effective as an adjuvant treatment in drug-resistant focal epilepsy in adult patients: an open-label prospective cohort study.

Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology, 44(1), 297-304

View on PubMed ↗Publisher’s paper ↗

Citation

Navarro, Cristian Eduardo. (2023). Cannabis-based magistral formulation is highly effective as an adjuvant treatment in drug-resistant focal epilepsy in adult patients: an open-label prospective cohort study.. Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology, 44(1), 297-304. https://doi.org/10.1007/s10072-022-06393-1