Antiepileptic drugs in Australia: 2002-2007

With the marketing of a number of new antiepileptic drugs (AEDs) in recent years it seemed possible that the pattern of Australian prescribing for patients with epilepsy may have been changing. We examined the trends in the prescribing of subsidised AEDs in the Australian population from 2002 to 2007.

We analysed the Medicare Australia and Drug Utilisation Sub-Committee databases for script data for AEDs from 2002 to 2007 in 5-year age groups by gender and by class of prescriber. Scripts were converted to defined daily doses (DDDs)/1000/day using Australian Bureau of Statistics population data.

Overall AED use (mainly valproate, lamotrigine and levetiracetam) increased progressively in 2002-2007 from 9.33 to 10.12 DDD/1000 population/day. Sodium valproate was the most widely used agent followed by carbamazepine then phenytoin. Amount of AED used increased in those aged in their 20s and 30s to plateau between 40 and 90 years. Use peaked in those aged 80-84 years and was slightly higher in males than females.

The rate of increase in the prescribing of AEDs remained steady between 2002 and 2007. The gender differences in prescribing reflect the higher prevalence of epilepsy in men and higher individual dosages used when many AEDs are prescribed on a body weight basis. The high use of some of these drugs in elderly people (> or =80 years) warrants further exploration. There is growing use of lamotrigine and gabapentin for indications apart from epilepsy-most likely neuropathic pain and mood disorders.