About one third of epileptic patients do not respond well to the conventional antiepileptic drugs.
Also, there are many side effects associated with them such as osteomalacia, anemia, etc. This demands a need for an antiepileptic drug in the market with better efficacy and lesser adverse effects. Cannabis derivatives are known for more than a century of having antiepileptic properties, and have got the attention of many researchers. Yet, these substances could not find a place in current prescription regime to treat seizures because of two main reasons. First, no sufficient trials have been done which could prove their efficacy in treating/preventing seizure episodes, and second, there are concerns about their safety over long-run. Endocannabinoids (cannabinoids synthesized normally within CNS) have role in decreasing the release of excitatory neurotransmitter in CNS, hence preventing from seizures 11.
This also provides a strong basis to explore substances with similar chemical properties as therapeutic means for seizure disorders. Cannabis is extracted from Cannabis Sativa plant, which has more tetrahydrocannabinol (THC) than that of cannabidiol (CBD). THC is psychoactive while CBD has little to no psycho-activity. Also, CBD has more antiepileptic properties, thus drawing attention to the preparations with more CBD to THC proportion 12.
In 1977, in an experiment in rats, it was postulated that the anticonvulsant effects of CBD could be compared with those of phenytoin, and protective effects to decrease relapses, were comparable to phenobarbital 13. Also, short term analysis has shown that CBD is a safe drug in humans with no psychotropic activity, no changes on clinical and laboratorial examination, and no effects on EEG and ECG were appreciated 13. Also, having the long half-life of CBD (30 hours when given through intravenous route and 23 hours when given orally) 14 will be helpful in patient compliance. Although limited number of studies has been done on CBD to appreciate its potential antiepileptic effects and many of them were carried out over a small duration of time (average of 3-4 months) and remained underpowered with maximum sample size of fifteen patients, to the best of our knowledge, until 2016. In 2016 and 2017, Devinsky, did trials to appreciate effects of CBD on seizures in patients with childhood onset seizures especially with Dravet syndrome. More than one hundred patient participants were in his studies.
He realized a good antiepileptic effect of CBD with a few adverse effects. Most of them were mild to moderate and included somnolence, decreased appetite, fatigue, diarrhea, and increased convulsions, that showed CBD might also have pro-convulsive properties 5,15. In some patients there was mildly elevation of liver function tests but that gradually returned to normal with continuous use of CBD 15. CBD, per se, has the anticonvulsant properties or it potentiates the effects of traditional antiepileptic is not yet clear. In 2017, an Australian Nationwide survey on medical cannabis use for epilepsy was carried out, which included 976 responders (patients with epilepsy and/or parents/guardians of patients with epilepsy). It showed that around fifteen percent of patients used cannabis, irrespective of their physician’s knowledge, to control their multi drug resistant seizures and to get rid of adverse effects associated with traditional antiepileptic drugs.
Most of them reported an improvement in their seizures 16.