Primary:~-to evaluate the efficacy of once daily (OD) administration of 60 mg and 100 mg phenobarbital, in reducing seizure frequency in participants with partial onset seizures (Type I seizures; complex or simple with motor symptoms only) not fully controlled despite treatment with 1 to 3 concomitant anti-epileptic drugs (AEDs) or AEDs with Vagus Nerve Stimulator (VNS)~Secondary:~to confirm dose response relationship of 60 and 100 mg phenobarbital doses,~to assess the effects of phenobarbital on Type I seizures,~to assess the safety of phenobarbital~to assess the tolerability of phenobarbital
Primary:~- to evaluate the efficacy of phenobarbital in reducing seizure frequency.~Secondary:~to confirm dose response relationship,~to assess the effects on Type I seizures,~to assess the safety of phenobarbital~to assess the drug tolerability.