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

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.

Utilisation and polypharmacy aspects of antiepileptic drugs in elderly versus younger patients with epilepsy: A pharmacoepidemiological study of CNS-active drugs in Norway, 2004-2015.

BACKGROUND AND PURPOSE: Many patients with epilepsy use antiepileptic drugs (AEDs) in combination. The elderly is a vulnerable group regarding polypharmacy. The purpose of this study was to investigate changes in utilisation of AEDs, and the extent of polypharmacy with other CNS-active drugs in elderly versus younger patients in Norway. METHODS: This pharmacoepidemiological study included all prescriptions of antiepileptic, antidepressant and antipsychotic drugs from Norwegian pharmacies in the Norwegian Prescription Database (NorPD) (2004-2015). Variables included number of patients, utilisation in defined daily doses, age, gender, and diagnosis specific reimbursement codes for AEDs. RESULTS: The use of AEDs has increased in all age groups in this population-based study in Norway. In the elderly, AEDs used in neuropathic pain (mainly gabapentin and pregabalin) have increased more than 10-fold (from 0.7 to 9.6 DDDs/1000 elderly/day, 2004-2015), while the prevalence of users is four times more than in younger patients. Polypharmacy between antiepileptic, antidepressant and antipsychotic drugs occurred in 35% of elderly and 38% of younger patients with epilepsy. The use of enzyme-inducers was common, and occurred more often in elderly patients. A total of 42 different interactions that may have clinical implications were identified among these drugs. CONCLUSION: The use of AEDs in elderly compared to younger patients is increasing, especially in neuropathic pain. Polypharmacy with antiepileptic, antidepressant and/or antipsychotic drugs was documented in more than one third of the patients. Awareness of increased drug utilisation, polypharmacy with potential drug interactions, and focus on elderly patients are important for increased patient safety.