Changes in utilisation of antiepileptic drugs in epilepsy and non-epilepsy disorders-a pharmacoepidemiological study and clinical implications

Abstract

Purpose: The purpose of this study was to investigate changes in utilisation of antiepileptic drugs (AEDs) in epilepsy and non-epilepsy disorders in Norway and furthermore to study the retention rates of the most commonly used AEDs in these indications in long-term use.

Methods: The data consisted of all prescriptions of AEDs from Norwegian pharmacies in the Norwegian Prescription Database (NorPD) (2004-2012). Variables included anonymous data regarding age, gender, diagnosis specific reimbursement codes and utilisation of AEDs.

Results: In recent years (2008-2012), the utilisation of AEDs in non-epilepsy disorders accounted for 45-53 % of the total use. In epilepsy, the most commonly used AED was lamotrigine, followed by levetiracetam, carbamazepine and valproate. Lamotrigine was also the predominant AED used in psychiatry, while pregabalin and gabapentin were mostly used in neuropathic pain. In migraine, topiramate predominated but accounted for <1 % of the total utilisation of AEDs. The majority of prescriptions were by general practitioners and only 20 % by specialists. Regardless of indication, newer AEDs had higher retention rates (34-48 %) and were used for a longer period before discontinuation.

Conclusions: The use of AEDs in non-epilepsy disorders is increasing and accounted for 53 % in 2012. Newer AEDs were predominantly used and demonstrated higher retention rates than older AEDs in all indications. This nationwide study demonstrates an increased exposure to AEDs in new patient groups, and details in prescription patterns and clinical and safety considerations should be closely monitored. This contributes to long-term post-marketing data of AED and accordingly improved pharmacovigilance.

Keywords: Antiepileptic drugs; Epilepsy; Non-epilepsy indications; Norwegian Prescription Database (NorPD); Pharmacoepidemiology; Pharmacovigilance; Retention rates.