A Double Blind, Randomized, Placebo-controlled, Two-part Study to Investigate the Pharmacokinetics, Followed by Efficacy and Safety of GWP42006 as add-on Therapy in Patients With Inadequately Controlled Focal Seizures.

Eligibility criteria

• For inclusion in Part B of the study patients must fulfil ALL of the following criteria:
• Male or female aged between 18 and 65 years, inclusive.
• Well-documented history of focal epilepsy, compatible electroencephalogram and clinical history.
• Documented computerized tomography / magnetic resonance imaging that shows no progressive neurologic abnormality.
• Has focal seizures despite prior treatment with at least two AEDs (whether as monotherapies or in combination).
• Currently treated with one to three AEDs.
• All medications or interventions for epilepsy (including ketogenic diet) must have been stable for one month prior to screening and the subject is willing to maintain a stable regimen throughout the study.
• Subject is willing to keep any factors expected to affect seizures stable (such as the level of alcohol consumption and smoking). The patient may not enter Part B of the study if ANY of the following apply:
• Time of onset of focal epilepsy treatment is less than two years prior to enrolment.
• Patient has seizures that are not of focal onset.
• Patient only has focal seizures without impairment of consciousness or awareness and without an observable motor component (even if autonomic component is present).
• Episode(s) of status epilepticus during one year prior to screening.
• History of pseudo-seizures.
• Vagus Nerve Stimulation, Deep Brain Stimulation, Responsive Neurostimulator System or other epilepsy neurostimulation device have been implanted or activated less than one year prior to screening, and/or stimulation parameters have been stable for less than one month, and/or battery life of unit not anticipated to extend for duration of trial.
• Had epilepsy surgery within one year of screening.
• Subject has clinically significant unstable medical conditions other than epilepsy.
• Subject has an illness in the four weeks prior to screening or randomization, other than epilepsy, which in the opinion of the investigator would affect seizure frequency.
• Subject has significantly impaired hepatic function at Visit 1.
• Active suicidal plan/intent in the past six months, or a history of suicide attempt in the last two years, or more than one lifetime suicide attempt .