Loiseau 1990.

Methods	Randomised, double‐blind, cross‐over study. Two treatment arms: 1 placebo, 1 lamotrigine. Five phases: Pre‐randomisation baseline = 4 weeks. Treatment I = 8 weeks. Washout I = 4 weeks. Treatment II = 8 weeks. Washout II = 4 weeks.
Participants	Single centre study from France. 25 adults, aged between 20 to 54 (mean 34.2 +/‐ 12.41) years. All had drug‐resistant partial epilepsy. 11 were randomised to lamotrigine and 14 to placebo in the first treatment phase. The duration of epilepsy ranged from 3 to 45 years (mean 17.4 +/‐ 10.81). Maximum number of other AEDs = 2.
Interventions	Add‐on lamotrigine or placebo. The median daily lamotrigine dose was 300 mg. Participants on valproate received lower doses.
Outcomes	(1) 50% responder rates. (2) Withdrawal from study for any reason. (3) Adverse effects.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random permuted blocks.
Allocation concealment (selection bias)	Low risk	Participants were allocated by sequentially numbered, sealed packages containing either lamotrigine or placebo.
Blinding (performance bias and detection bias) All outcomes	Low risk	Neurologists, participants and parents were blinded. Investigators were blinded. All treatments (tablets) and packaging were identical. Pre‐packed coded medication dispensed by pharmacy.
Incomplete outcome data (attrition bias)	Low risk	No participants were excluded from analysis. 2 participants withdrew from the study; 1 receiving lamotrigine and 1 receiving placebo. The reasons for exclusion were reported.
Selective reporting (reporting bias)	Low risk	All outcomes stated in methods section of paper were reported in the results. There was no protocol available to check a priori outcomes.
Other bias	Unclear risk	This study was sponsored by GlaxoSmithKline, the manufactures of LTG.