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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



The safety and efficacy of a formulation high in cannabidiol (CBD) and low in ∆9-tetrahydrocannabinol (THC) to treat drug-resistant epilepsy have been examined previously in children, but not in adult population. The aim of this study was to evaluate whether CBD-rich oil, as an add-on treatment to conventional antiepileptic drugs, was effective, safe, and well-tolerated in adults with drug-resistant focal epilepsy (DRFE).


An open-label, prospective cohort, single-center in adult patients with DRFE, were receiving stable doses of antiepileptic drugs (AEDs). A cannabis based-magistral formulation (CBMF) (100 mg/ml CBD and THC <1.9 mg/ml) was administrated 0.1 ml sublingually every 12 hours, up-titrated weekly. The primary outcome was to establish a reduction in seizures frequency >50% at 12 weeks. Adverse-drug reactions monitoring was done. p-value <0.05 was statistically significant.


Between August 2020 and July 2022, 44 (38.6%) patients completed >3 months of follow-up. The median daily dose of CBD was 200 mg, that of THC was 4 mg, and that of CBD per kilogram of weight was 3.7 mg. The median number of seizures per month before CBD treatment was 11, and after CBD treatment was 2.5 (p<0.001). A reduction in seizures >50% at 12 week was achieved in 79.5% of the patients. The median percentage change in seizure frequency per month was 84.1% at 12 weeks. Five patients reported any adverse-drug reactions.


The CBMF is a highly effective and safety therapy to treat adult patients with DRFE. The reduction in seizures frequency is maintained over time.

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To patients and their families who agreed to participate in this observational study.


This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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Authors and Affiliations



Cristian Eduardo Navarro MD MSc: conceptualization, review of literature, data collection, data analysis, writing, and editing the manuscript. The author read and approved the final manuscript.

Corresponding author

Correspondence to Cristian Eduardo Navarro.

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Ethical approval

The institutional review board approved the study.

Consent to participate and for publication

Patients provided written informed consent to participate and to use a cannabis-based magistral formulation (CBMF).

Conflict of interest

Cristian Eduardo Navarro MD MSc works at Clínica Zerenia in Bogotá (Colombia) which is a reference center specializing in medical cannabis therapy owned by Khiron Life Science Corp®. Khiron Life Science Corp.® manufactures the cannabis-based magistral formulation used in this study.

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Informed consent was provided by each patient at the beginning of the study.

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Navarro, C.E. 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. Neurol Sci 44, 297–304 (2023).

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