Incidence of seizure exacerbation and seizures reported as adverse events during adjunctive treatment with eslicarbazepine acetate: A pooled analysis of three Phase III controlled trials

Objective To investigate whether adjunctive eslicarbazepine acetate (ESL) could lead to exacerbation of seizures in some patients. Methods Post-hoc analysis of data pooled from three Phase III trials of adjunctive ESL (studies 301, 302, and 304) for refractory partial-onset seizures (POS). Following an 8-week baseline period, patients were randomized to receive placebo or ESL 400, 800, or 1,200 mg once daily (2-week titration, 12-week maintenance, 2-4 week tapering-off periods). Patient seizure diary data and seizure treatment-emergent adverse event (TEAE) reports were pooled for analysis. Results The modified intent-to-treat and safety populations comprised 1,410 patients and 1,447 patients, respectively. Titration period: Compared with placebo (32/21%), significantly smaller proportions of patients taking ESL 800 mg (20/15%) and 1,200 mg (22/12%) had a ≥25/≥50% increase in standardized seizure frequency (SSF) from baseline; there was no significant difference between placebo and ESL 400 mg. Maintenance period: Compared with placebo (20%), significantly smaller proportions of patients taking ESL (400 mg, 12%; 800 mg, 12%; 1,200 mg, 14%) had an increase in SSF ≥25%. When evaluating ≥50% increases in SSF, only ESL 800 mg (7%) was significantly different from placebo (12%). Some patients had no secondarily generalized tonic-clonic (sGTC) seizures during baseline but had ≥1 sGTC seizure during maintenance treatment (placebo, 11%; ESL 400 mg, 5%; 800 mg, 10%; 1,200 mg, 5%). Fewer patients had a ≥25% increase in sGTC seizure frequency with ESL (400 mg, 11%; 800 mg, 9%; 1,200 mg, 14%) versus placebo (19%). The incidence of seizures reported as TEAEs was low in all treatment groups; incidences were generally lower with ESL versus placebo. Tapering-off period: Similar proportions of patients taking ESL and placebo had a ≥25/≥50% increase in SSF. Seizure TEAE incidence was numerically higher with ESL versus placebo. Significance Treatment with adjunctive ESL does not appear to aggravate POS or sGTC seizures.