Effect of Valproic Acid Concentration on Photic Response

Inclusion Criteria: * Male or female patients * Aged 15 to 65 years * Patients with a diagnosis of epilepsy for which they are either taking up two AEDs, not including VPA/divalproex, or no AEDs * Patients with a reproducible IPS-induced photo-paroxysmal responses of at least 7 SPR-EEG units as measured at two different time points in the day (pm screening Study Visit 1 and am of Visit 2). * Are in good health (with the exception of epilepsy). * Able and willing to provide written informed consent. Exclusion Criteria: * Patients not exhibiting a photo-paroxysmal-EEG response * Patients with active psychogenic seizures * Women who are pregnant or lactating * Women of reproductive potential who do not agree to use effective birth-control methods during the study and for one week after receiving study drug. * Patients taking any dosage form of VPA/divalproex within 4 weeks prior to the study * Patients taking more than two concomitant AEDs * Patients with any clinically significant laboratory abnormality, which in the opinion of the investigator, will exclude the patient from the study * Patients who are suffering from active liver disease indicated by abnormal liver function tests greater than three times the upper limit of normal (AST and ALT), patients with porphyria, or patients with a family history of severe hepatic dysfunction * Patients with a history of alcoholism, drug abuse, or drug addiction (within the past 12 months) * Patients with a history of sensitivity or a…