Drug utilization pattern of anti-epileptic drugs: a pharmacoepidemiologic study in Oman

To get an insight into the type and aetiology of epileptic seizures; to describe the drug utilization pattern of anti-epileptic drugs (AEDs) for the treatment of various forms of epileptic seizures in this tertiary referral centre in Oman; and to compare our drug utilization pattern with that from other countries. In addition, the tolerability of AEDs and the use of therapeutic drug monitoring (TDM) were evaluated.

In a 6-month study, all epileptic patients aged 14 and above who were prescribed an AED were considered for analysis. Demographic data, type and aetiology of epileptic seizures, AED data, tests performed and adverse drug reaction (ADR) data were collected.

A total of 1039 prescriptions originated from 488 epileptic patients. The age ranged from 14 to 77 years (median, 24 years). Generalized tonic-clonic seizures (51%) of idiopathic/cryptogenic origin (83%) were the most common type and aetiology of epileptic seizures, respectively. An average of 1.34 AEDs per patient was prescribed with 78% of patients being on monotherapy. Sodium valproate (49%) was the most frequently prescribed AED, followed by carbamazepine (44%), phenytoin (12%) and lamotrigine (11%). Ten patients suffered an ADR and phenobarbital followed by carbamazepine were most commonly the subject of TDM.

Unlike the results in most other studies, generalized seizures represented the majority of epileptic seizures. The selection of the AEDs corresponded well with their known efficacy profiles for specific epileptic seizure types. Monotherapy was the type of therapy most frequently used, and sodium valproate and carbamazepine were the most commonly used AEDs.