All partial onset seizures experienced during treatment phase were recorded by central reader during the 48 to 72 hour video-electroencephalogram (EEG). Double Blind 24 hour EEG seizure rate for all partial onset seizures = ([Number of seizures in double blind 48 to 72 hour EEG assessment] divided by [number of hours of video-EEG monitoring])*24. The EEG assessment was done at the end of the fixed dose treatment. For log-transformation, the quantity 1 was added to the double blind 24 hour EEG seizure rate for all participants to account for any possible "0" seizure incidence. This resulted in final calculation as: log transformed (double-blind 24-hour EEG seizure rate + 1).

Modified intent-to-treat (mITT) population included all randomized participants who took at least one dose of study drug during the double-blind treatment phase, had a baseline with at least one partial onset seizure identified by video-EEG (at least 24 hours of evaluable monitoring) and a treatment phase video-EEG.

Responder Rate was defined as percentage of participants who had a 50% or greater reduction from baseline in 24-hour seizure rate during the double-blind treatment phase. Double Blind 24 hour EEG seizure rate for all partial onset seizures = ([Number of seizures in double blind 48 to 72 hour EEG assessment] divided by [number of hours of video-EEG monitoring])*24. The EEG assessment was done at the end of the fixed dose treatment.

mITT population included all randomized participants who took at least one dose of study drug during the double-blind treatment phase, had a baseline with at least one partial onset seizure identified by Video-EEG (at least 24 hours of evaluable monitoring) and a treatment phase Video-EEG.

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. An SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment-emergent AEs were events which occurred between first dose of study drug and up to end of study (up to Day 25) that were absent before treatment or that worsened relative to pre-treatment state. AEs included both serious and non-serious adverse events.

Safety population included all randomized participants who received at least 1 dose of study drug.

Treatment-related AE was any untoward medical occurrence attributed to study drug in a participant who received study drug. An SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment-emergent AEs were events which occurred between first dose of study drug and up to end of study (up to Day 25) that were absent before treatment or that worsened relative to pre-treatment state. Relatedness to drug was assessed by the investigator. AEs included both serious and non-serious adverse events.

Safety population included all randomized participants who received at least 1 dose of study drug.

An AE was any untoward medical occurrence attributed to study drug in a participant who received study drug. AEs were classified according to the severity in 3 categories a) mild: AEs does not interfere with participant's usual function b) moderate: AEs interferes to some extent with participant's usual function c) severe: AEs interferes significantly with participant's usual function.

Safety population included all randomized participants who received at least 1 dose of study drug.

Abnormality Criteria: hemoglobin,hematocrit,red blood cells(RBC)count:<0.8*lower limit of normal[LLN],platelets:<0.5*LLN/>1.75*upper limit of normal[ULN]; leukocytes:<0.6*LLN/>1.5*ULN; lymphocytes,neutrophils, total protein,albumin, tetraiodothyronine,thyroid stimulating hormone:<0.8*LLN/>1.2*ULN; basophils,eosinophils,monocytes:>1.2*ULN; prothrombin [PT],PT international ratio:>1.1*ULN; aspartate aminotransferase,alanine aminotransferase,alkaline phosphatase,gamma glutamyl transferase:>0.3*ULN; bilirubin:>1.5*ULN; blood urea nitrogen,creatinine, cholesterol,triglycerides:>1.3*ULN; sodium: <0.95*LLN/>1.05*ULN; potassium,chloride,calcium,bicarbonate:<0.9*LLN/>1.1*ULN; glucose fasting:<0.6*LLN/>1.5*ULN; creatine kinase:>2*ULN;urine glucose,ketone,protein:>=1;urine WBC,RBC:>= 20/High Power Field[HPF]; urine casts,hyaline casts:>1/Low Power Field; urine bacteria:>20/HPF.

Safety population included all randomized participants who received at least 1 dose of study drug. Here, "Overall number of participants analyzed"= number of participants who were evaluable for this outcome measure.

Criteria for abnormalities in vital signs included: sitting/supine systolic blood pressure (SBP) values: maximum increase and decrease of greater than or equal to (>=) 30 millimeter of mercury (mmHg) from baseline; sitting/supine diastolic blood pressure (DBP) value: maximum increase and decrease of >=20 mmHg from baseline.

Safety population included all randomized participants who received at least 1 dose of study drug.

Physical examinations evaluated the following body systems/organs: abdomen; ears; extremities; eyes; general appearance; head; heart; lungs; lymph nodes; mouth; musculoskeletal; nose; skin and throat. Abnormalities in physical examination were based on investigator's discretion.

Safety population included all randomized participants who received at least 1 dose of study drug. Here, "number analyzed" signifies number of participants who were evaluable for the specified category for each arm respectively.

Neurological examinations included: coordination; cranial nerve function (CNF); gait and station; level of consciousness (LOC); lower and upper extremity sensation; muscle strength; muscle tone; nystagmus; reflexes and speech. Abnormalities in neurological examination were based on investigator's discretion and also, some components of the neurological examination were not done for certain participants due to participant age or significant developmental impairment. Only those categories of neurological examination in which at least 10% of participants had an abnormality in any treatment group at any time point were reported in this outcome measure.

Safety population included all randomized participants who received at least 1 dose of study drug. Here, "number analyzed" signifies number of participants who were evaluable for the specified category for each arm respectively.

Criteria for abnormalities in ECG findings: 1) Time from ECG Q wave to the end of the S wave corresponding to ventricle depolarization (QRS complex): >=140 milliseconds (msec); 2) The interval between the start of the P wave and the start of the QRS complex, corresponding to the time between the onset of the atrial depolarization and onset of ventricular depolarization (PR interval): >=200 msec; 3) Time from ECG Q wave to the end of the T wave corresponding to electrical systole corrected for heart rate using Fridericia's formula (QTCF interval): absolute value 450 to <480 msec, 480 to <500 msec, >=500 msec; 4) Maximum QT interval: >=500 msec; 5) Maximum QTCB interval (Bazett's correction): 450 to< 480 msec, 480 to <500 msec, >=500 msec. Only those categories of ECG abnormalities in which participants were found abnormal (maximum QTCB interval 450-<480 msec), were reported in this outcome measure.

Safety population included all randomized participants who received at least 1 dose of study drug.