Animal research (Shirazizand et al. 2013, Jones et al. 2012, Jones et al. 2011), anecdotal evidence and one clinical study (Cunha et al. 1980) show that CBD has anti-epileptic properties. In phase 1 of the only clinical study conducted so far, 3 mg/kg daily of CBD was given for 30 days to 8 healthy human volunteers (Cunha et al. 1980).
Another 8 volunteers received the same number of identical capsules containing glucose as placebo in a double-blind setting. Neurological and physical examinations, blood and urine analysis, ECG and EEG were performed at weekly intervals. In phase 2 of the study, 15 patients suffering from secondary generalized epilepsy with temporal focus were randomly divided into two groups. Each patient received, in a double-blind procedure, 200-300 mg daily of CBD Drops or placebo. The drugs were administered for along as 4 1/2 months. Throughout the experiment, the patients continued to take the antiepileptic drugs prescribed before the experiment, although these drugs no longer controlled the signs of the disease. All patients and volunteers tolerated CBD very well and no signs of toxicity or serious side effects were detected on examination. 4 of the 8 CBD subjects remained almost free of convulsive crises throughout the experiment and 3 other patients demonstrated partial improvements in their clinical condition. CBD was ineffective in 1 patient. The clinical condition of 7 placebo patients remained unchanged whereas the condition of 1 patient clearly improved.
CBD reduced seizures in mice, in which seizures were caused by pentylenetetrazol (PTZ) and electroshocks (Shirazizand et al. 2013). CBD also showed antiepileptic effects in two other animal models of seizures (Jones et al. 2012). In the pilocarpine model CBD significantly reduced the percentage of animals experiencing the most severe seizures. In the penicillin model, CBD significantly decreased the percentage of mortality as a result of seizures; CBD also decreased the percentage of animals experiencing the most severe tonic-clonic seizures. According to research at the University of Reading, UK, CBD exerted anti-convulsant effects in animal models of the temporal lobe and partial seizures (Jones et al. 2011).