Abstracts

Rationale: Clobazam (CLB) was approved by the US FDA in October 2011 for treatment of seizures associated with Lennox-Gastaut Syndrome in patients 2 years of age and older. While CLB and clonazepam (CLN) have been used for many years in Europe for a variety of disorders, no long-term data exist comparing their respective uses in adults. The Clinical Practice Research Datalink (CPRD) database, a large, longitudinal primary care database, consists of electronic medical records from general practitioners located throughout the United Kingdom (UK). With CPRD data, we compared patients ≥18 years of age receiving CLB vs. CLN for epilepsy in routine UK clinical practice. Methods: Patients with ≥1 incident prescription of CLB or CLN within the study period (1995-2011) were included. Date of a patient's first prescription was termed index date. Patients must have also had ≥182 days in the database before index date without any prescriptions of CLB or CLN, to ensure that no previous CLB or CLN had been prescribed. We then evaluated results for the subgroups of adult patients who had a diagnosis of epilepsy any time prior to or ≤90 days after index date. Results: A total of 21,099 patients met inclusion criteria. Of these, 3,882 received CLB, and 17,217 received CLN. CLB use has been predominantly in epilepsy (76.1%), while CLN use in epilepsy was just 8.7%. The population of interest (patients with epilepsy ≥18 years of age) included 2,312 and 1,268 adults who had received CLB and CLN, respectively (table). Adult patients with epilepsy in the CPRD database treated with CLB vs. CLN were younger (p<0.0001). A greater percentage of CLB vs. CLN patients were receiving concomitant AEDs (p<0.0001) and were BZD-naïve (p<0.002) at baseline. CLB patients also had a greater follow-up period (p<0.0023), on average, and a greater mean treatment duration (p<0.12). Median CLB dosage did not increase from baseline to last follow up, while median CLN dosage increased 25%. Conclusions: The younger age of CLB patients, as well as their greater use of concomitant AEDs, may indicate that they were being treated for more severe epilepsy than those receiving CLN. CLB dosage appeared to remain stable over time, while CLN dosage appeared to increase from baseline to last follow up, suggesting the possible development of tolerance to this benzodiazepine.