Cannabidiol modifies the seizure expression and effects of antiseizure drugs in a rat model of recurrent severe seizures.

Abstract Purpose : To evaluate the effects of cannabidiol alone or in combination with antiseizure drugs in the expression of recurrent generalized seizures in a rat model. Methods : Group A: Male Wistar rats received 3-mercaptopropionic acid (MP) every 12 h for 5 days to induce recurrent generalized seizures. Thereafter, the animals were submitted to a crossover protocol to receive different treatments with cannabidiol, phenytoin and phenobarbital, alone and in combination. Group B: Rats were manipulated as group A, but they received cannabidiol during the induction of recurrent seizures. Results : Minor and major seizures were induced after each MP administration. Status epilepticus (SE) detected during the last MP administrations was considered a sign of high seizure severity. Cannabidiol did not modify the expression of the MP induced seizures but reduced the prevalence of SE in both experimental groups. Phenytoin decreased the expression of major seizures but did not modify the prevalence of SE (groups A and B). Cannabidiol combined with phenytoin did not modify these effects. Phenobarbital diminished the expression of major seizures, an effect more evident when combined with cannabidiol (groups A and B). The combination of phenobarbital and cannabidiol reduced the expression of SE of group B. The mortality rate of groups A and B at the end of the crossover protocol was 30% and 9%, respectively (p=0.2). Conclusion : CBD associated with appropriate antiseizure drugs reduces the severity and prevalence of generalized seizures. In contrast, CBD alone reduces the seizure severity, but does not avoid the expression of generalized seizures.