Pharmacokinetics and tolerability of eslicarbazepine acetate and oxcarbazepine at steady state in healthy volunteers

Purpose Investigate the pharmacokinetics of once-daily (QD; 900mg) and twice-daily (BID; 450mg) regimens of eslicarbazepine acetate (ESL) and BID (450mg) regimen of oxcarbazepine (OXC) at steady state in healthy volunteers. Methods Single-center, open-label, randomized, three-way (n=12) crossover studies in healthy volunteers. Key Findings Mean eslicarbazepine C-max,C-ss (in m) following ESL QD (87.3) was 33.3% higher (p<0.05) compared to ESL BID (65.5) and 82.1% higher (p<0.05) compared to OXC BID (48.0). The mean area under the curve (AUC)(ss,0-) (in molh/L) following the last dose of an 8-day repeated dosing was 1156.3, 1117.6, and 968.4 for ESL QD, ESL BID, and OXC BID, respectively. The ratio eslicarbazepine plasma exposure (molh/L) to ESL daily-dose (mol) was 0.381 (1156.3:3037.3), 0.368 (1117.6:3037.3), and 0.271 (968.4:3567.6) for ESL-QD, ESL-BID, and OXC-BID, respectively, which translates into a 40.6% increase in the ability of ESL-QD compared to OXC-BID to deliver into the plasma their major active entity eslicarbazepine. The extent of plasma exposure to ESL minor metabolites: (R)-licarbazepine and oxcarbazepine after ESL-QD was 71.5% and 61.1% lower, respectively, than after OXC-BID. Twenty, 24 and 38 treatment emergent adverse events were reported with ESL-QD, ESL-BID, and OXC-BID, respectively. Significance ESL-QD resulted in 33.3% higher peak plasma concentration (C-max,C-ss) of eslicarbazepine and similar extent of plasma exposure (AUC(ss,0-)) when compared to ESL-BID, which may contribute to the efficacy profile reported with once-daily ESL. In comparison to OXC-BID, administration of ESL-QD resulted in 40.6% increase in the delivery of eslicarbazepine into the plasma as well as a significantly lower systemic exposure to (R)-licarbazepine and oxcarbazepine.