Drug–drug interaction between clobazam and cannabidiol in children with refractory epilepsy

• Published in: Epilepsia (Copenhagen) Vol. 56; no. 8; pp. 1246 - 1251
• Main Authors: Geffrey, Alexandra L., Pollack, Sarah F., Bruno, Patricia L., Thiele, Elizabeth A.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.08.2015
• Subjects: Adolescent; Antiepileptic drugs; Benzodiazepines - metabolism; Benzodiazepines - therapeutic use; Cannabidiol - metabolism; Cannabidiol - therapeutic use; Cannabis; Child; Child, Preschool; Cytochrome P-450 Enzyme System - metabolism; Cytochrome P450 pathway; Drug Interactions; Epilepsy - drug therapy; Female; Humans; Male; Norclobazam; Treatment‐resistant epilepsy; Young Adult; Norclobazam; Cytochrome P450 pathway; Cannabis; Treatment-resistant epilepsy; Antiepileptic drugs
• ISSN: 0013-9580; 1528-1167; 1528-1167
• DOI: 10.1111/epi.13060

Summary Objective Under an expanded access investigational new drug (IND) trial, cannabidiol (CBD) is being studied as a possible adjuvant treatment of refractory epilepsy in children. Of the 25 subjects in the trial, 13 were being treated with clobazam (CLB). Because CLB and CBD are both metabolized in the cytochrome P450 (CYP) pathway, we predicted a drug–drug interaction, which we evaluate in this article. Methods Thirteen subjects with refractory epilepsy concomitantly taking CLB and CBD under IND 119876 were included in this study. Demographic information was collected for each subject including age, sex, and etiology of seizures, as well as concomitant antiepileptic drugs (AEDs). CLB, N‐desmethylclobazam (norclobazam; nCLB), and CBD levels were measured over the course of CBD treatment. CLB doses were recorded at baseline and at weeks 4 and 8 of CBD treatment. Side effects were monitored. Results We report elevated CLB and nCLB levels in these subjects. The mean (± standard deviation [SD]) increase in CLB levels was 60 ± 80% (95% confidence interval (CI) [−2–91%] at 4 weeks); the mean increase in nCLB levels was 500 ± 300% (95% CI [+90–610%] at 4 weeks). Nine of 13 subjects had a >50% decrease in seizures, corresponding to a responder rate of 70%. The increased CLB and nCLB levels and decreases in seizure frequency occurred even though, over the course of CBD treatment, CLB doses were reduced for 10 (77%) of the 13 subjects. Side effects were reported in 10 (77%) of the 13 subjects, but were alleviated with CLB dose reduction. Significance Monitoring of CLB and nCLB levels is necessary for clinical care of patients concomitantly on CLB and CBD. Nonetheless, CBD is a safe and effective treatment of refractory epilepsy in patients receiving CLB treatment.