Epilepsy: Antiseizure Drug Interactions with Cannabidiol

Research into the use of the marijuana derivative cannabidiol (CBD) is just beginning. In an abstract presented at the American Epilepsy Society 69th Annual Meeting in Philadelphia, PA, a team described their ongoing work. Misty Smith, PhD, a research assistant professor at the University of Utah in Salt Lake City, UT, and colleagues are looking at how cannabidiol interacts with traditional anti-seizure drugs.

The current project compares the relative anticonvulsant efficacy of CBD with five mechanistically-different ASDs (i.e., carbamazepine (CBZ), valproate (VPA), levetiracetam (LEV), clobazam (CBM), and lacosamide (LAC)). The studies test the hypothesis that CBD will have supra-additive (synergistic) effects when administered in combination with mechanistically-different, yet compatible, ASDs without enhancing adverse events.

So far, they have identified "significant synergistic interaction" with LEV at the 1:1 fixed ratio (FR) combination (P<0.01), whereas significant antagonistic interactions have been identified with CBM at the 1:3 FR combination (P<0.05) and at the 1:3 and 3:1 FR combinations with CBZ (P<0.001). Isobolographic studies on the FR combinations of cannabidiol and lacosamide are currently underway. Additional ongoing studies are evaluating the 1:1 FR combination of CBD:LEV in preclinical models of anxiety, depression, and locomotor activity.

The team's goal is to gain "a better understanding of the nature of the CBD:ASD interactions." They hope such knowledge may inform polytherapy to optimize therapeutic safety and efficacy of CBD use.