PHARMACOKINETICS: Once-daily Oxtellar XR (oxcarbazepine). MHD plasma concentrations in healthy adults at steady state12-14
Single-center, multi-dose, open-label, randomized, 2-treatment crossover study14
Oxtellar XR 1200 mg QD
Abbreviation: MHD, 10-monohydroxy derivative. Adapted from date on file, Supernus Pharmaceuticals.
PHASE 3 TRIAL: Safety and efficacy (including long-term safety [OLE]) of Oxtellar XR (oxcarbazepine) as adjunctive therapy in patients with refractory partial-onset seizures12-16
AEs in phase 3 controlled clinical trial and OLE occurring in ≥5% of patients receiving Oxtellar XR (oxcarbazepine) with concomitant AEDs and more frequent than with placebo1,13,14,16
Cognitive AEs were similar to placebo in the controlled randomized trial14
5% discontinuation rate due to adverse events in the 1 year OLE14,16
For a complete listing of AEs ≥2%, see the full Prescribing Information. Discontinuation rate due to AEs in the phase 3 Oxtellar XR (oxcarbazepine) study was 30% in the 2400 mg/day group, 15% in the 1200 mg/day group, and 8% in the placebo group.12
OLE study limitations16
AED additions/withdrawals may influence partial-onset seizure control. Many patients entering OLEs have already demonstrated tolerability of study medication during double-blind treatment and therefore may be less likely to withdraw due to AEs. Patient retention may also be influenced by the intensive follow-up that occurs in a clinical study.
Phase 3 clinical study design12-14
Multinational, multicenter, double-blind, randomized, placebo-controlled, 3-arm, parallel-group, phase 3 trial (PROSPER) of 366 adult patients having a diagnosis of epilepsy with uncontrolled partial-onset seizures with or without secondary generalization, taking a stable regimen of 1 to 3 concomitant AED(s), experiencing an average of 6 partial-onset seizures per 28 days.
Phase 3 efficacy12,13,15
For the ITT population (N=366), the median percent partial-onset seizure frequency change over the 16-week double-blind treatment period was 29% for placebo (n=121) vs 38% (P=0.078) for Oxtellar XR (oxcarbazepine) 1200 mg/day (n=122) and 43% (P=0.003) for Oxtellar XR (oxcarbazepine) 2400 mg/day (n=123). For the North American post hoc analysis (n=116), results were: 13% for placebo (n=41); 35% (P=0.022) for Oxtellar XR (oxcarbazepine) 1200 mg/day (n=40); and 53% (P=0.006) for Oxtellar XR (oxcarbazepine) 2400 mg/day (n=35).
OLE study design16
Key inclusion criteria for initial double-blind, placebo-controlled study (16 weeks): adults (aged 18 to 66 years) with inadequately controlled partial-onset seizures (baseline frequency: ≥3 seizures/28 days) despite taking 1 to 3 concomitant AED(s) at stable doses. Blinded conversion over 3 weeks to 12 months in an open-label, once-daily Oxtellar XR (oxcarbazepine) 1200 mg/day, with subsequent dose adjustments as clinically indicated (increments/decrements, 300 mg/day to 600 mg/day; maximum dosage, 2400 mg/day).
No new safety signals and no clinically significant changes from baseline in vital signs, ECGs, or laboratory values with 1 year of open-label treatment16
Abbreviations: AEs, adverse events; AEDs, antiepileptic drugs; ITT, intent to treat; OLE, open-label extension; PROSPER, Prospective, Randomized Study of OXC XR in Subjects with Partial Epilepsy, Refractory.
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