Safety and tolerability of oxcarbazepine in elderly patients with epilepsy

Abstract

Despite the high incidence of seizures and epilepsy in the elderly, the tolerability and safety of anticonvulsants are rarely evaluated in this patient population. We compared the safety and tolerability of oxcarbazepine in a cohort of 52 patients aged 65 years and older and a group of 1574 adult patients ranging in age between 18 and 64 years. There was no significant difference between the two groups with respect to premature discontinuation due to adverse events. The four most common adverse events experienced by patients in the elderly group, irrespective of their causal relationship to oxcarbazepine, were vomiting (19%), dizziness (17%), nausea (17%), and somnolence (15%). Three patients developed an asymptomatic hyponatremia, with at least one serum sodium level below 125 mEq/L. Elderly patients on concomitant natriuretic drugs were significantly more likely to develop serum sodium levels below 135 mEq/L. The results indicate that oxcarbazepine is safe to use in elderly patients and that its tolerability in this age group is similar to that of younger adult patients.

Introduction

The incidence of epilepsy is highest among children and the elderly [1]. Studies have found that approximately 30% of new-onset epilepsies occur in patients over 65 years of age, and that the prevalence of epilepsy in patients older than 70 years is nearly twice that in children [1]. In addition, the age-adjusted incidence of unprovoked seizures jumps from 62 per 100,000 person years in the general population to 150 per 100,000 person years after 60 years of age [1]. The elderly population is not a homogenous group and can be demographically divided into three subgroups as the young old (65–74), the old (75–84), and the oldest old (85+). According to data from the National Institute on Aging, the elderly population in the United States will, by the year 2005, grow to 19 million in the young old group, 16 million in the old group, and 2 million in the oldest old age group. These are impressive numbers especially since epidemiological studies have shown that the incidence of epilepsy continues to increase every decade after 60 years of age [1]. With the life expectancy getting progressively longer in the industrialized world, the prevalence of epilepsy in the elderly can only be expected to rise in the future.

Besides its high incidence and prevalence, epilepsy in the elderly is of importance because of various features that differentiate it from epilepsy in younger patients. For instance, the underlying causes of epilepsy are different in the elderly, with strokes accounting for most of the identifiable cases of recurrent seizures [2]. Seizures can also result in more serious consequences in the elderly, because of propensity for a prolonged postictal state and an increased risk of significant head trauma and fractures. In addition, elderly patients are more susceptible to develop adverse events following treatment with antiepileptic drugs (AEDs) [3]. This is partly due to the presence of comorbidities requiring concomitant treatment with a number of drugs coupled with age-related reduction in renal and hepatic functions. Because of such differences, it is important to specifically evaluate the efficacy, tolerability, and safety of anticonvulsants in the elderly population.

Oxcarbazepine (Trileptal) is a second-generation antiepileptic drug (AED) with proven efficacy as monotherapy and combination therapy in the treatment of partial seizures (including seizure subtypes of simple, complex, and partial seizures evolving to secondarily generalized seizures) in adults and children ages 4–16 with epilepsy. The aim of this analysis was to evaluate the safety and tolerability of oxcarbazepine in an elderly patient population. Another objective was to compare the type and frequency of adverse events in this population with those in a group of younger adults treated with oxcarbazepine.