Drug therapy
Anti-epileptic drugs (AEDs) are the most common form of therapy. Complete control is achievable in approximately 70% of older adults.7 New AEDs should be considered as first-line therapy for elderly patients with seizures.3 As with all drugs given to older adults, treatment should start low and progress slowly. Table 1 below lists guidelines for initial maintenance doses and rates of titration. It should be noted, however, that these are data from middle-aged and elderly people. It may be necessary to start even lower and proceed more slowly in elders.8
Since 1983, eight new AEDs have been introduced (see Table 2 below). Sadly, a recent VA study of more than 21,000 subjects aged 65 years and older revealed that 80% were being treated with phenobarbital or phenytoin.9 Because of significant side effects and drug interactions, neither is a first-line choice in the management of older adults. Phenytoin may occasionally be used for those who do not respond to other drug therapies (see Table 2 below for older AEDs).
Absence seizures. Ethosuximide is a preferred agent for absence seizures. Valproic acid is also considered preferred, especially when the older adult has a combination of absence and other partial or generalized seizures.10
Partial and generalized seizures (excluding absence). Partial complex seizures are subtle and can be difficult to diagnose. As monotherapy and adjunctive therapy, carbamazepine, valproic acid, and lamotrigine are all equally effective and considered preferred agents.10 Lamotrigine has been studied more in older adults than the other drugs and so may be considered the drug of choice; it is effective and well tolerated and has few side effects. Oxcarbazepine has been found to reduce seizure frequency of newly diagnosed and refractory partial seizures in clinical practice.11,12 A newer drug, vigabatrin, for refractory partial epilepsy, is useful as add-on therapy in reducing seizure frequency.13 However, many patients withdraw from therapy because of fatigue and drowsiness, and there can be visual-field defects that are often not detected.
Status epilepticus. Treatment guidelines of the Epilepsy Foundation of America (EFA) state that this situation should be managed with a rapid-acting IV benzodiazepine. Lorazepam is the agent of choice by virtue of its rapid onset and longer duration compared with diazepam.10 Status epilepticus is more common in adults older than 60, and its morbidity and mortality are significantly higher in this age group.14
Drug interactions/side effects. Drug management in older adults is a great concern of primary-care clinicians. Age-related changes in physiology are common. Comorbid conditions, such as hepatic and renal diseases, change the pharmacodynamics and pharmacokinetics of drugs. See Table 1 for drug excretion. Elders with hepatic dysfunction may do better with an AED that is primarily excreted by the kidney, and those elders with renal insufficiency may require a reduced dose.3
The mean number of co-medications reported in the older population is six.15 Although patients often require more than one AED to manage epilepsy, taking more than one increases risk for cognitive dysfunction.4,16 Patients may be less attentive and have less initiative and poorer memory than older adults on monotherapy. In general, older community-dwelling adults with epilepsy seem to have more impairments on cognitive measures compared with healthy controls.17 Seizure onset and duration have not been found to be associated with cognitive dysfunction.
Drug-resistant seizures. About 80% of people with epilepsy obtain significant relief with drug therapy.18 The other 20%, primarily those with partial epilepsy, have seizures that are not controlled with medications. About 90% of older adults with epileptic seizures have this type. In children, it takes 15 or more years for epilepsy to become intractable to medications; in older adults, it takes a much shorter time—immediately to within a few years.
According to a recent study from the United Kingdom,8 older adults do have a better chance of remission at 12 months and at 24 months compared with middle-aged people with epilepsy.