Methods	Randomised double-blind PCB controlled parallel multicentre (43 in USA and Canada) trial. 3 treatment arms: 1 PCB, 2 PGB. Patients randomised in blocks of 6, each allocated unique ID number. All patients received TDS regimen of blinded capsules (no further information available). Duration of baseline period: 8 weeks. 1-week titration period and 11-week treatment period
Participants	Adults aged 17 to 82 years (mean 39.1 years), 50.2% male, all with treatment-resistant partial epilepsy confirmed by history and recent EEG. Patients were on 1 to 4 baseline AEDs. 378 patients screened, 313 patients randomised: 98 patients to PCB (mean baseline 28-day seizure frequency: 25.1), 104 patients to 300 mg PGB BD (mean baseline 28-day seizure frequency: 21.5), and 111 patients to 200 mg PGB TDS (mean baseline 28-day seizure frequency: 21.3)
Interventions	Group 1: PCB Group 2: 300 mg PGB BD (1-week titration phase) Group 3: 200 mg PGB TDS (1-week titration phase)
Outcomes	Primary outcome: reduction in seizure frequency compared to baseline (response ratio) Secondary outcomes: responder rate, median percentage change in seizure frequency
Notes	One patient randomised to the 300 mg BD group failed to take tablets, and therefore was excluded from ITT analysis. Blinding was broken with 1 patient in the PCB arm when she became pregnant
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Patients randomised in blocks of 6 and al located unique ID number
Allocation concealment (selection bias)	Unclear risk	No details provided
Blinding (performance bias and detection bias) All outcomes	Low risk	All patients received identical capsules
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rates reported. ITT analysis employed
Selective reporting (reporting bias)	Unclear risk	All outcomes stated in methods section of paper were reported in the results; however, there was no protocol available to check a priori outcomes
Other bias	High risk	Sponsored by same pharmaceutical company (Pfizer Ltd.) as with all the other included trials