An international, double-blind, parallel-group, placebo-controlled, randomized study: evaluation of the efficacy and safety of phenobarbital as adjunctive therapy in participants (≥ 17 to 70 years old) with partial onset seizures

INTERVENTION: Product Name: Phenobarbital Product Code: Phenobarbital Pharmaceutical Form: Tablet INN or Proposed INN: Phenobarbital CAS Number: 50‐06‐6 Current Sponsor code: Phenobarbital Other descriptive name: Phenobarbital Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 15‐ Pharmaceutical form of the placebo: Tablet Route of administration of the placebo: Oral use Product Name: Phenobarbital Product Code: Phenobarbital Pharmaceutical Form: Tablet INN or Proposed INN: Phenobarbital CAS Number: 50‐06‐6 Current Sponsor code: Phenobarbital Other descriptive name: Phenobarbital Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 30‐ Pharmaceutical form of the placebo: Tablet Route of administration of the placebo: Oral use Product Name: Phenobarbital Product Code: Phenobarbital Pharmaceutical Form: Tablet INN or Proposed INN: Phenobarbital CAS Number: 50‐06‐6 Current Sponsor code: Phenobarbital Other descriptive name: Phenobarbital Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 60‐ Pharmaceutical form of the placebo: Tablet Route of administration of the placebo: Oral use Product Name: Phenobarbital Product Code: Phenobarbital Pharmaceutical Form: Tablet INN or Proposed INN: Phenobarbital CAS Number: 50‐06‐6 Current Sponsor code: Phenobarbital Other descriptive name: Phenobarbital Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 100‐ Pharmaceutical form of the placebo: Tablet Route of administration of the placebo: Oral use CONDITION: Epilepsy with partial onset seizures (complex or simple with motor symptoms only) whether or not secondarily generalized. ; MedDRA version: 13.1 Level: LLT Classification code 10015037 Term: PRIMARY OUTCOME: Main Objective: 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; according International League Against Epilepsy [ILAE]) not fully controlled despite treatment with 1 to 3 concomitant anti‐epileptic drugs (AEDs) or AEDs with Vagus Nerve Stimulator (VNS). Primary end point(s): The primary efficacy variable is the partial onset seizure (Type I; complex or simple [with motor symptoms only]) frequency per week over the Treatment Period, excluding up‐ and down‐titration periods. Secondary Objective: • To confirm the dose response relationship of 60 mg and 100 mg phenobarbital doses; ; • To assess the effects of phenobarbital on Type I seizures; and ; • To assess the safety and tolerability of phenobarbital.; ; ; INCLUSION CRITERIA: 1) Participants from 17 to 70 years (inclusive); 2) Participants with a history of Type I partial onset seizures (complex or simple [with motor symptoms only]; according to the ILAE classification; 1981) whether or not secondarily generalized; 3) Participants must have had, within the last 10 years, one electroencephalogram (EEG) or video EEG and/or one brain magnetic resonance imaging (MRI) or computerized tomography (CT) with results consistent with a diagnosis of partial‐onset seizures. If these have not been performed in the last 10 years, or if the records of these are not available, an EEG and CT or MRI will be performed as part of the screening procedures; 4) Participants having at least eight Type I partial onset seizures (complex or simple [with motor symptoms only]) whether or not secondarily generalized, during the 8‐week Baseline Period 5) Participants being uncontrolled while treated by 1 to 3 permitted concomitant AED(s) and/o