Cannabinoids for epilepsy.
BACKGROUND
Marijuana appears to have anti-epileptic effects in animals. It is not currently known if it is effective in patients with epilepsy. Some states in the United States of America have explicitly approved its use for epilepsy.


OBJECTIVE
To assess the efficacy of marijuana, or one of marijuana's constituents in the treatment of people with epilepsy.


METHODS
We searched the Cochrane Epilepsy Group Specialized Register (May 15, 2012), the Cochrane Central Register of Controlled Trials (CENTRAL issue 4 of 12, The Cochrane Library 2012),MEDLINE (PubMed, searched on May 15, 2012), ISI Web of Knowledge (May 15, 2012), CINAHL (EBSCOhost, May 15, 2012), and ClinicalTrials.gov (May 15, 2012). In addition, we included studies we personally knew about that were not found by the searches, as well as references in the identified studies.


METHODS
Randomized controlled trials (RCTs), whether blinded or not.


METHODS
Two authors independently selected trials for inclusion and extracted data. The primary outcome investigated was seizure freedom at one year or more, or three times the longest interseizure interval. Secondary outcomes included: responder rate at six months or more, objective quality of life data, and adverse events.


RESULTS
We found four randomized reports which included a total of 48 patients, each of which used cannabidiol as the treatment agent. One report was an abstract, and another was a letter to the editor. Anti-epileptic drugs were continued in all. Details of randomisation were not included in any study. There was no investigation of whether control and treatment groups were the same or different. All the reports were low quality.The four reports only answered the secondary outcome about adverse effects. None of the patients in the treatment groups suffered adverse effects.


CONCLUSIONS
No reliable conclusions can be drawn at present regarding the efficacy of cannabinoids as a treatment for epilepsy. The dose of 200 to 300 mg daily of cannabidiol was safely administered to small numbers of patients, for generally short periods of time, and so the safety of long term cannabidiol treatment cannot be reliably assessed.
Department of Neurology, University of California, Los Angeles, California, USA. dgloss@ucla.edu
David
D
Gloss
Barbara
B
Vickrey
D000927:Anticonvulsants / Q000627:therapeutic use*; D002185:Cannabidiol / Q000627:therapeutic use*; D004827:Epilepsy / Q000188:drug therapy*; D006801:Humans; D016032:Randomized Controlled Trials as Topic
D000927:Anticonvulsants; D002185:Cannabidiol