Intravenous carbamazepine as short-term replacement therapy for oral carbamazepine in adults with epilepsy: Pooled tolerability results from two open-label trials

Objective: To report tolerability findings and maintenance of seizure control from a pooled analysis of phase I open-label trial OV-1015 (NCT01079351) and phase III study 13181A (NCT01128959).

Methods: Patients receiving a stable oral dosage of carbamazepine were switched to an intravenous (IV) carbamazepine formulation solubilized in a cyclodextrin matrix (at a 70% dosage conversion) for either a 15- or a 30-min infusion every 6 h for up to 7 days and then switched back. A subset of patients who tolerated 15-min infusions also received 2- to 5-min (rapid) infusions. Assessments included physical and laboratory evaluations, electrocardiography (ECG) studies, as well as adverse event (AE) monitoring for tolerability. Convulsion/seizure AE terms and data from seizure diaries were used as proxies for the assessment of consistency of seizure control between formulations.

Results: Of the 203 patients exposed to IV carbamazepine (30 min, n = 43; 15 min, n = 160), 113 received 149 rapid infusions. During infusion, the most commonly reported AEs (≥ 5%) were dizziness (19%), somnolence (6%), headache (6%), and blurred vision (5%). IV carbamazepine was not associated with clinically relevant cardiac AEs. The tolerability profile appeared similar between patients who received <1,600 mg/day (n = 174) and ≥ 1,600 mg/day (n = 29) carbamazepine. Cyclodextrin exposure was not associated with clinically relevant changes in AEs or renal biomarkers. Seizure control was maintained as patients transitioned between oral and IV carbamazepine.

Significance: IV carbamazepine administered as multiple 30- or 15-min infusions every 6 h, and as a single rapid infusion, was well tolerated as a short-term replacement in adults with epilepsy receiving stable dosages of oral carbamazepine. Infusion site reactions, which were generally mild, were the only unique AEs identified; seizure control was generally unchanged when patients were switching between formulations.