Zonisamide for refractory juvenile absence epilepsy

The landscape of drug resistant absence seizures in adolescents and adults: Pathophysiology, electroclinical spectrum and treatment options

The persistence of typical absence seizures (AS) in adolescence and adulthood may reduce the quality of life of patients with genetic generalized epilepsies (GGEs). The prevalence of drug resistant AS is probably underestimated in this patient population, and treatment options are relatively scarce. Similarly, atypical absence seizures in developmental and epileptic encephalopathies (DEEs) may be unrecognized, and often persist into adulthood despite improvement of more severe seizures. These two seemingly distant conditions, represented by typical AS in GGE and atypical AS in DEE, share at least partially overlapping pathophysiological and genetic mechanisms, which may be the target of drug and neurostimulation therapies. In addition, some patients with drug-resistant typical AS may present electroclinical features that lie in between the two extremes represented by these generalized forms of epilepsy.

Current concepts in the management of idiopathic generalized epilepsies

Idiopathic generalized epilepsies (IGEs) are a group of epilepsies characterized by an underlying genetic predisposition and a good response to antiseizure medicines (ASMs) in the majority of the patients. Of the various broad-spectrum ASMs, valproate is the most effective medicine for the control of seizures in IGEs. However, with the availability of many newer ASMs and evidence showing the high teratogenic potential of valproate, the choice of ASMs for IGEs has become increasingly difficult, especially in women of the child-bearing age group. In this article, we review the current evidence regarding the efficacy and safety of various ASMs in patients with IGEs and provide practical guidelines for choosing appropriate ASMs in various subgroups of patients with IGEs.

Alternatives to valproate in girls and women of childbearing potential with Idiopathic Generalized Epilepsies: state of the art and guidance for the clinician proposed by the Epilepsy and Gender Commission of the Italian League Against Epilepsy (LICE)

Following recent European Medication Agency restrictions on valproate (VPA) use in girls and women of childbearing potential (WOCP), the Commission on Epilepsy and Gender of the Italian League against Epilepsy integrated current literature and legislative data in order to provide clinicians with guidance on antiseizure medication (ASM) prescription for Idiopathic Generalized Epilepsies (IGEs) in this population, avoiding VPA. We reviewed the updated literature on ASMs and examined the teratogenicity of those showing efficacy in IGEs. For all relevant ASMs, we considered the indications for use and the pregnancy and contraception-related recommendations given in the Italian Summary of Product Characteristics (SmPC) and on the websites of the European Medicines Agency (EMA) and other European Union (EU) countries' regulatory agencies. With the exception of absence seizures, the literature lacks high quality studies on ASMs in IGEs. In girls and WOCP, levetiracetam and lamotrigine should be considered the first-choice drugs in Generalized Tonic-Clonic Seizures Alone and in Juvenile Myoclonic Epilepsy, lamotrigine in Juvenile Absence Epilepsy, and ethosuximide in Childhood Absence Epilepsy. Although supported by the literature, several ASMs are off label, contraindicated or burdened by special warnings in pregnancy. Some discrepancies emerged between the various SmPC warnings for different brands of the same active principle. We provided a therapeutic algorithm for each IGE syndrome and highlighted the need for revised prescription rules, consistent with the latest literature data, uniformity of SmPC warnings for the same active principle, and more data on the efficacy of new ASMs in IGEs and their safety in pregnancy.

Pharmacological Management of the Genetic Generalised Epilepsies in Adolescents and Adults

Common genetic generalised epilepsy syndromes encountered by clinicians include childhood and juvenile absence epilepsies, juvenile myoclonic epilepsy and generalised tonic-clonic seizures on awakening. Treatment of these syndromes involves largely the use of broad-spectrum antiseizure drugs. Those effective for the generalised epilepsies include sodium valproate, phenobarbital, ethosuximide, clobazam, clonazepam, lamotrigine, levetiracetam, topiramate, zonisamide and, more recently, perampanel and brivaracetam. Results from the few rigorous studies comparing outcomes with drugs for genetic generalised epilepsies show valproate to be the most effective. The majority of patients with genetic generalised epilepsy syndromes will become seizure free on antiseizure monotherapy; those for whom control proves elusive may benefit from combination regimens. Early counselling regarding management may assist the patient to come to terms with their diagnosis and improve long-term outcomes. Treatment can be lifelong in some individuals, although others may remain seizure free without medication. Choice of antiseizure medication depends on the efficacy for specific seizure types, as well as tolerability. For patients prescribed comedication, drug interactions should be considered. In particular, for young women taking oral hormonal contraceptives, ≥ 200 mg/day of topiramate can decrease the circulating concentration of ethinylestradiol and ≥ 12 mg/day of perampanel can induce levonorgestrel metabolism. The use of valproate in women of childbearing potential is limited by associated teratogenic and neurodevelopmental effects in offspring. Given that valproate is often the antiseizure drug of choice for genetic generalised epilepsies, this creates a dilemma for patients and clinicians. Decision making can be aided by comprehensive assessment and discussion of treatment options. Psychiatric comorbidities are common in adolescents and adults with genetic generalised epilepsies. These worsen the prognosis, both in terms of seizure control and quality of life. Attendant lifestyle issues can impact significantly on the individual and society. Frontal lobe dysfunction, which can present in patients with juvenile myoclonic epilepsy, can adversely affect the long-term outlook, regardless of the nature of seizure control. Ongoing management requires consideration of psychosocial and behavioural factors that can complicate diagnosis and treatment. An assured supportive attitude by the neurologist can be an important contributor to a positive outcome. The mechanisms underlying genetic generalised epilepsies, including genetic abnormalities, are unclear at present. As the pathophysiology is unravelled, this may lead to the development of novel therapies and improved outcomes for patients with these syndromes.

Antiepileptic Drugs and Liver Disease

Acute, symptomatic seizures or epilepsy may complicate the course of hepatic disease. Choosing the most appropriate antiepileptic drug in this setting represents a difficult challenge, as most medications are metabolized by the liver. This article focuses on the acute and chronic treatment of seizures in patients with advanced liver disease and reviews the hepatotoxic potential of specific antiepileptic drugs. Newer antiepileptic drugs without, or with minimal, hepatic metabolism, such as levetiracetam, lacosamide, topiramate, gabapentin, and pregabalin should be used as first-line therapy. Medications undergoing extensive hepatic metabolism, such as valproic acid, phenytoin, and felbamate should be used as drugs of last resort. In special circumstances, as in patients affected by acute intermittent porphyria, exposure to most antiepileptic drugs could precipitate attacks. In this clinical scenario, bromides, levetiracetam, gabapentin, and vigabatrin constitute safe choices. For the treatment of status epilepticus, levetiracetam and lacosamide, available in intravenous preparations, are good second-line therapies after benzodiazepines fail to control seizures. Hepatotoxicity is also a rare and unexpected side effect of some antiepileptic drugs. Drugs such as valproic acid, phenytoin, and felbamate, have a well-recognized association with liver toxicity. Other antiepileptic drugs, including phenobarbital, benzodiazepines, ethosuximide, and the newer generations of antiepileptic drugs, have only rarely been linked to hepatotoxicity. Thus physicians should be mindful of the pharmacokinetic profile and the hepatotoxic potential of the different antiepileptic drugs available to treat patients affected by liver disease.

Could Adult European Pharmacoresistant Epilepsy Patients Be Treated With Higher Doses of Zonisamide?

OBJECTIVE

To examine the clinical effect (efficacy and tolerability) of high doses of zonisamide (ZNS) (>500 mg/d) in adult patients with pharmacoresistant epilepsy.

METHODS

Between 2006 and 2013, all epileptic outpatients treated with high doses of ZNS were selected. Safety and efficacy were assessed based on patient and caregiver reports. Serum levels of ZNS and other concomitant antiepileptic drugs were evaluated if available.

RESULTS

Nine patients (5 female): 8 focal/1 generalized pharmacoresistant epilepsy. Mean age: 34 years. Most frequent seizure type: complex partial seizures; other seizure types: generalized tonic-clonic, tonic, myoclonia. Zonisamide in polytherapy in all (100%), administered in tritherapy in 3 (33%) of 9 patients; mean dose: 633 (600-700) mg/d; efficacy (>50% seizure reduction) was observed in 5 (55%) of 9 patients. Five of 9 patients are still taking high doses of ZNS (more than 1 year). Adverse events were observed in 3 (37%) of 8 patients. Good tolerance to high doses of other antiepileptic drugs had been observed in 6 (66%) of 9 patients. Plasma levels of ZNS were only available in 2 patients; both were in the therapeutic range (34.95, 30.91) (10-40 mg/L).

CONCLUSIONS

High doses of ZNS are effective and safe in pharmacoresistant epileptic patients. Therapeutic drug monitoring of ZNS may be considered at therapeutic failure.