Antiepileptic Drug Formulation and Treatment in the Elderly: Biopharmaceutical Considerations

Early versus late switch over of antiseizure medications from intravenous to the oral route in children with seizures: Single-blinded, randomized controlled trial (ELAIO trial)

INTRODUCTION

Early switch-over of anti-seizure medications (ASMs) from intravenous to oral route may reduce the duration of hospitalization, drug acquisition costs, and behavioral upset in hospitalized children with seizures.

OBJECTIVE

The primary objective was to compare short-term seizure recurrence within 1 week in hospitalized children aged 1 month to 18 years with new-onset/breakthrough seizures after an early versus late switch-over from intravenous to the oral route of ASMs. Secondary objectives were to compare the incidence of status epilepticus, duration of hospital stay, drug acquisition costs, and caregiver-reported satisfaction scores in both groups.

METHODS

In this single-blind randomized controlled trial, patients with seizures were categorized based on the number of ASMs required and the history of status epilepticus. Patients in each category were randomized in a 1:1 ratio into either early or late switch-over (ES or LS) groups. In the ES groups, ASMs were tapered one-by-one between 0 and 24 hours of seizure freedom, while in the LS groups, they were tapered one-by-one between 24 and 48 hours of seizure freedom.

RESULTS

A total of 112 children were enrolled in the study, with 56 in each arm. Seizure recurrence at 1 week and 12 weeks was comparable in ES and LS groups (3/55 vs. 1/54 at 1 week, p=0.61; 7/49 vs. 6/49 at 12 weeks, p=0.98). Drug acquisition costs were significantly lower in the ES group (393±274 vs. 658±568 INR, p=0.002). Thrombophlebitis and dysphoria were significantly more common in the LS group (p=0.008 and 0.03, respectively).

CONCLUSION

The early switch-over of ASMs from intravenous to oral route is safe without any significant increased risk of short-term seizure recurrence and also associated with a reduction in the incidence of thrombophlebitis and ASM acquisition costs.

TRIAL REGISTRATION NO

CTRI/2021/03/032145.

Managing Status Epilepticus in the Older Adult

The aim of this systematic review was to describe particularities in epidemiology, outcome, and management modalities in the older adult population with status epilepticus. There is a higher incidence of status epilepticus in the older adult population, and it commonly has a nonconvulsive presentation. Diagnosis in this population may be difficult and requires an unrestricted use of EEG. Short and long term associated-mortality are high, and age over 60 years is an independent factor associated with poor outcome. Stroke (acute or remote symptomatic), miscellaneous metabolic causes, dementia, infections hypoxemia, and brain injury are among the main causes of status epilepticus occurrence in this age category. The use of anticonvulsive agents can be problematic as well. Thus, it is important to take into account the specific aspects related to the pharmacokinetic and pharmacodynamic changes in older critically-ill adults. Beyond these precautions, the management may be identical to that of the younger adult, including prompt initiation of symptomatic and anticonvulsant therapies, and a broad and thorough etiological investigation. Such management strategies may improve the vital and functional prognosis of these patients, while maintaining a high overall quality of care.

Clinical pharmacokinetics of new-generation antiepileptic drugs at the extremes of age: an update

Epilepsies occur across the entire age range, and their incidence peaks in the first years of life and in the elderly. Therefore, antiepileptic drugs (AEDs) are commonly used at the extremes of age. Rational prescribing in these age groups requires not only an understanding of the drugs' pharmacodynamic properties, but also careful consideration of potential age-related changes in their pharmacokinetic profile. The present article, which updates a review published in 2006 in this journal, focuses on recent findings on the pharmacokinetics of new-generation AEDs in neonates, infants, children, and the elderly. Significant new information on the pharmacokinetics of new AEDs in the perinatal period has been acquired, particularly for lamotrigine and levetiracetam. As a result of slow maturation of the enzymes involved in glucuronide conjugation, lamotrigine elimination occurs at a particularly slow rate in neonates, and becomes gradually more efficient during the first months of life. In the case of levetiracetam, elimination occurs primarily by renal excretion and is also slow at birth, but drug clearance increases rapidly thereafter and can even double within 1 week. In general, infants older than 2-3 months and children show higher drug clearance (normalized for body weight) than adults. This pattern was confirmed in recent studies that investigated the pediatric pharmacokinetics of several new AEDs, including levetiracetam, rufinamide, stiripentol, and eslicarbazepine acetate. At the other extreme of age, in the elderly, drug clearance is generally reduced compared with younger adults because of less efficient drug-metabolizing activity, decreased renal function, or both. This general pattern, described previously for several AEDs, was confirmed in recent studies on the effect of old age on the clearance of felbamate, levetiracetam, pregabalin, lacosamide, and retigabine. For those drugs which are predominantly eliminated by renal excretion, aging-related pharmacokinetic changes could be predicted by measuring creatinine clearance (CLCR). Overall, most recent findings confirm that age is a major factor influencing the pharmacokinetic profile of AEDs. However, pharmacokinetic variability at any age can be considerable, and the importance of other factors should not be disregarded. These include genetic factors, co-morbidities, and drug interactions, particularly those caused by concomitantly administered AEDs which induce or inhibit drug-metabolizing enzymes.

The Controversy over Generic Antiepileptic Drugs

As patent protection ends for the next generation of antiepileptic drugs (AEDs), a complex debate continues over generic substitution of AEDs. On one hand, generic drug formulations provide cost savings for patients and society. On the other hand, patients with epilepsy and physicians are wary about the adequacy and efficacy of the Food and Drug Administration's (FDA) standards for generics. This article reviews current and proposed bioequivalence test procedures, summarizes new generic AED formulations and their costs, and discusses potential pitfalls in the current standards. These shortcomings include certain pharmacokinetic factors and clinical pharmacologic factors that may affect bioequivalence of generic AEDs, and statistical limitations of the standards. While the drug concentration differences between the brand name drug and each generic formulation are unlikely to be substantial, the differences with generic-to-generic switches will be greater and potentially clinically significant. Conversely, owing to their more favorable pharmacokinetic profile, newer AEDs may be less prone to problems with generic substitution than older ones. Unfortunately, very few data are available to guide decisions regarding what is best for an individual patient. Based on new prediction methods, generic substitution should be safe for many patients but identifying them ultimately requires more rigorous study.

Epilepsy in older women

Women suffering from epilepsy require special attention throughout their life. In this review, management of epilepsy during the periods of perimenopause, menopause and late maturity is discussed. The effect of epilepsy on age at menopause, changes in seizure frequency during perimenopause and menopause, and the risks of hormone replacement therapy are also presented. Altered antiepileptic drug pharmacokinetics with increasing age and the management of this vulnerable population is also discussed.