Pharmacokinetic considerations about antiseizure medications in the elderly

Epilepsy represents the third most common neurological disorder in the elderly. Antiseizure medications (ASMs) are often used not only to treat epilepsy but also other disorders in this age group. Many physio-pathological changes occur in body composition and organ or system functions with aging. Furthermore, drug-drug interactions (DDIs) represent a major risk considering the prevalence of polytherapy in the elderly.

Relevant studies on the pharmacokinetics of ASMs in the elderly were identified through a literature search. We have reviewed all available data on known alterations in pharmacokinetic parameters of ASMs in elderly also considering pathophysiological alterations such as renal function impairment. Finally, we have highlighted the potential risk of DDIs with some drug classes.

Large interindividual variability also due to co-morbidities and related co-therapies makes elderly patients a not homogeneous group. Overall, a reduction in loading and maintenance doses of almost all ASMs should be considered to avoid adverse events (AEs) as well as a slow titration, following the rule 'start low and go slow'. Therapeutic drug monitoring should be performed to apply the 'individual therapeutic concentration' and implemented to overcome the age-related differences between dose and plasma concentrations, to monitor DDIs and guide dosage adjustments.