Therapeutic use of medicinal cannabis in difficult to manage epilepsy.

Abstract

Intractable epilepsy is currently defined by the International League Against Epilepsy as failure of adequate trials of two tolerated and appropriately chosen antiepileptic drugs (AED) to achieve sustained seizure freedom 1. Approximately 33% of adults and 20% of children with epilepsy meet that definition 2. This is despite the fact that there are 25 registered AED with a particular explosion of new drugs over the past 3 decades. That increased number of drugs surprisingly has not led to a significant reduction in the proportion of people who have intractable epilepsy. Thus, there was great hope in the epilepsy community (mainly patients and their families) that medicinal cannabis would bridge this gap. Cannabis had been used for millennia (especially in Asia) to treat a great variety of ailments including epilepsy. In the 19th century, its use became more mainstream in the western world with several neurologists documenting its efficacy and safety in small case series 3. Used alone or in combination with other treatments such as bromide, cannabinoids were the mainstay of epilepsy treatment until the development of phenobarbital (1912) and phenytoin (1937), which were proven to be efficacious. So why the recent resurgence of interest? A combination of the power of the Internet, vested interests such as agri‐business and marijuana legalization groups and growing public distrust of institutions and science 4. One just has to search the internet for ‘epilepsy and cannabis’ and often the same individual cases are recycled as examples of the next miracle cannabis cure of epilepsy. This Internet‐magnified confirmation bias of anecdotal reports has polarized views, bred distrust of doctors (and their requirement for evidence‐based medicine) and provided considerable hope but minimal help to those suffering with epilepsy and their carers. This review will focus mainly on cannabidiol (CBD), the most researched compound of the Cannabis sativa derivatives.