This phase III study ( N01252 ; NCT00490035 ) evaluated the efficacy and safety/tolerability of BRV ( 20 , 50 , and 100 mg/day ) compared with placebo ( PBO ) in patients aged 16-70 years with uncontrolled focal seizures with/without secondary generalization , despite treatment with one to two concomitant antiepileptic drugs at a stable and optimal dosage .