ABSTRACT
INTRODUCTION: Both levetiracetam (LEV) and brivaracetam (BRV) eliminate the electroencephalogram photoparoxysmal response (PPR) in the human phase IIa photosensitivity model of epilepsy. The physiochemical properties of BRV differ from those of LEV, having higher potency and lipophilicity plus 10- to 15-fold greater affinity for synaptic vesicle glycoprotein 2A. OBJECTIVE: We compared the rapidity of the effects of both drugs in the central nervous system (CNS) of patients with photosensitive epilepsy using time to PPR elimination post-intravenous infusion as a pharmacodynamic endpoint. METHODS: Using a randomized, double-blind, two-period, balanced, crossover design, we tested patients with photosensitive epilepsy with equipotent milligram doses of intravenous LEV 1500 mg versus BRV 100 mg post-15-min intravenous infusion (part 1) and post-5-min intravenous infusion (part 2, same doses). Eight patients per part were deemed sufficient with 80% power to determine a 70% reduction for intravenous BRV:LEV intrapatient time ratio to PPR elimination, with a 0.05 two-sided significance level. Plasma antiseizure medicine concentrations were measured using liquid chromatography/mass spectrometry. RESULTS: Nine patients [six women; mean age 27.8 years (range 18-42)] completed the study; seven of these participated in both parts 1 and 2. In 31 of 32 instances, patients experienced PPR elimination. In mixed-effects model time analysis, BRV eliminated PPRs more quickly than did LEV (median 2 vs. 7.5 min, respectively). However, no statistically significant difference in BRV:LEV time ratio to PPR elimination was observed for two of our multiple primary outcomes: for the 15-min infusion alone (p = 0.22) or the 5-min infusion alone (p = 0.11). However, BRV was faster when we excluded an outlier patient in part 1 (p = 0.0016). For our remaining primary outcome, parts 1 and 2 data combined, the median intrapatient BRV:LEV time ratio was 0.39 [95% confidence interval (CI) 0.16-0.91], i.e., PPR elimination was 61% faster with BRV, p = 0.039. PPR was completely eliminated in ≤ 2 min in 11 patients with BRV and in four patients with LEV. No period or carryover effects were seen. No serious or severe adverse effects occurred. At PPR elimination (n = 16), median plasma [BRV] was 250 ng/mL (range 30-4100) and median plasma [LEV] was 28.35 µg/mL (range 1-86.7). CONCLUSION: Outcome studies directly comparing LEV and BRV are needed to define the clinical utility of the response with BRV, which was several minutes faster than that with LEV. CLINICAL TRIALS: ClinTrials.gov Identifier = NCT03580707; registered 07-09-18.
