Evaluate efficacy and safety of eslicarbazepine acetate (ESL) as adjuvant therapy to concomitant carbamazepine (CBZ), lamotrigine (LTG), levetiracetam (LEV), or GABA mimetic antiepileptic drug (AED) (phenobarbital, lorazepam and clonazepam).

Theoretically, AED combinations with the same mechanism of action may be less adequate than targeting different mechanisms of action.

Data were pooled from four Phase 3, randomized, double-blind, placebo-controlled trials (2093-301, -302, -303 -304). After an 8-week baseline period, adults with ≥4 focal seizures/month, taking 1–3 AEDs were randomized to placebo, ESL 800 mg or ESL 1200 mg QD (2-week titration; 12-week maintenance).

Most patients were treated with 1 or 2 AEDs: CBZ: 682 (49.1%), LTG: 308 (22.2%), LEV: 277 (19.9%) and GABA mimetic AEDs: 201 (14.5%). Responder rate: 22.2%, 33.8%, 43.1% for placebo, ESL 800 mg, 1200 mg, respectively.  ESL was associated with higher responder rate (vs. placebo) as add-on to CBZ (Relative Risk, RR: ESL 800 mg, 1.66; ESL 1200 mg, 2.10); LTG (ESL 1200 mg, 2.39); LEV (RR: ESL 1200 mg, 2.40); GABA mimetic AEDs (RR: ESL 1200 mg: 1.87). ESL 1200 mg and concomitant LEV and LTG had the highest association with responder rate. Most frequent TEAE leading to discontinuation: dizziness (5.6%), nausea (3.1%), vomiting (2.8%). ESL as add-on to treatment regimens containing LEV had the lowest frequency of discontinuation due to TEAE: dizziness (2.9%), nausea (1.4%); lowest frequency of TEAE: dizziness (13%), somnolence (8.7%), nausea (6.3%). ESL as add-on to treatment regimens containing CBZ had the highest frequency of TEAE and discontinuation due to TEAE.

ESL was efficacious and well tolerated as add-on treatment to CBZ, LTG, LEV and GABA mimetic AEDs in adult patients with focal seizures. ESL as add-on to treatment regimens containing LEV appeared to be associated with lower incidences of some TEAEs.