Historical trend toward improved long-term outcome in childhood absence epilepsy.

We retrospectively analyzed published studies to investigate historical trends in outcome of childhood absence epilepsy (CAE). We included patients based on onset of absence seizures in childhood, 3 Hz bilateral spike-wave discharges on EEG, and availability of seizure-free outcome data. The primary endpoint was seizure-freedom off medications by study publication year. We also analyzed relationships between seizure-freedom and 1. treatment medication, and 2. CAE diagnostic criteria. We included 29 studies published 1945-2013, encompassing 2416 patients. Seizure-freedom off medications was higher for studies after 1985 versus before 1975 (82% versus 35%; p < 0.001). Ethosuximide and valproate were used more commonly after 1985, and patients previously treated with ethosuximide or valproate had higher seizure-freedom off medications than those treated only with other medications (64% versus 32%; χ2>10; p < 0.001). Although differences in diagnostic criteria for early vs. later studies did not reach statistical significance, later studies tended to use normal EEG background (p = 0.09) and absence of comorbid disorders (p = 0.09) as criteria more commonly. These findings demonstrate that seizure-freedom off medications has improved in published CAE studies after 1985. Our results are limited due to retrospective analysis. Further work is needed with prospective, controlled trials to establish factors leading to improved long-term prognosis in CAE.

How did phenobarbital's chemical structure affect the development of subsequent antiepileptic drugs (AEDs)?

Phenobarbital has been in clinical use as an antiepileptic drug (AED) since 1912. The initial clinical success of phenobarbital and other barbiturates affected the design of subsequent AEDs (e.g., phenytoin, primidone, ethosuximide), developed between 1938 and 1962, the chemical structures of which resemble that of phenobarbital. However, the empirical discovery of carbamazepine (1962) and the serendipitous discovery of valproic acid (1967) led to subsequent AEDs having chemical structures that are diverse and completely different from that of phenobarbital. Sixteen AEDs were introduced between 1990 and 2012. Most of these AEDs were developed empirically, using mechanism-unbiased anticonvulsant animal models. The empirical nature of the discovery of these AEDs, coupled with their multiple mechanisms of action, explains their diverse chemical structures. The antiepileptic market is therefore crowded. Future design of new AEDs must have a potential for treating nonepileptic central nervous system (CNS) disorders (e.g., bipolar disorder, neuropathic pain, migraine prophylaxis, or restless legs syndrome). The barbiturates were once used as sedative-hypnotic drugs, but have been largely replaced in this role by the much safer benzodiazepines. In contrast, phenobarbital is still used worldwide in epilepsy. Nevertheless, the development of nonsedating phenobarbital derivatives will answer a clinical unmet need and might make this old AED more attractive.

Drug treatment of epilepsy in the century of the ILAE: the second 50 years, 1959-2009.

The drug therapy of epilepsy evolved enormously in this 50 year period. Advances in therapeutics included the incorporation of pharmacokinetics into clinical practice, enormous advances in neurochemistry, a trend to antiepileptic drug monotherapy, better drug assessment, better understanding of therapeutic outcomes, and the recognition of the large epilepsy treatment gap in many countries. An unprecedented range of new drugs was introduced in this period. Before 1989, these included carbamazepine, valproate, ethosuximide, and the benzodiazepines. Since 1989, 13 more new drugs have been licensed and marketed and there are others in the pipeline. The International League Against Epilepsy and its leading figures have played an important role in these developments. In this period, too, there has been a rapid expansion in research and development within the pharmaceutical industry and a rise in the value of the antiepileptic drug market. In parallel, governmental regulation of pharmaceuticals has greatly increased. To what extent the overall prognosis of epilepsy has improved as a result of these activities is an interesting and perplexing question.

Oxcarbazepina en el trastorno bipolar y trastornos esquizoafectivos / Oxcarbazepine in the bipolar and schizoaffective disorders

Desde la década de 1970 con el valproato y la carbamazepina varios fármacos antiepilépticos se han establecido como opciones terapéuticas en el trastorno bipolar. Según el nivel I de la medicina basada en la evidencia se ha confirmado la eficacia del valproato y la carbamazepina en el tratamiento de la manía, si bien su papel en el tratamiento de mantenimiento es menos evidente que el del litio. La lamotrigina ha demostrado también con un nivel I de evidencia su eficacia en el tratamiento de la depresión y el mantenimiento del trastorno bipolar. La oxcarbazepina es un cetoanálogo de la carbamazepina con similar estructura y perfil antiepiléptico. La oxcarbazepina tiene menos efectos secundarios importantes y menos interacciones farmacológicas que la carbamazepina y el valproato. La evidencia disponible sugiere que la oxcarbazepina puede ser efectiva en el tratamiento de la manía y en el tratamiento de mantenimiento del trastorno bipolar. Son necesarios nuevos estudios doble-ciego controlados con placebo que lo confirmen definitivamente (AU)

Starting in the 1970s with valproate and carbamazepine several anticonvulsant drugs have been established as treatment option in bipolar disorder. Level I of evidence based medicine confirm the efficacy of valproate and carbamazepine in the treatment of mania but their role in maintenance therapy is less clear than of lithium. Level I of evidence based medicine also confirm the efficacy of lamotrigine in the treatment of depression and in the maintenance therapy of bipolar disorder. Oxcarbazepine is a chemical keto-derivative of carbamazepina with a similar structure and antiepileptic profile. Oxcarbazepine has less severe adverse effects and less pharmacological interactions than carbamazepine and valproate. The available evidence suggest that oxcarbazepine may be effective in the treatment of mania and in the maintenance treatment of bipolar disorder. Further double-blind placebo controlled studies are needed for confirm this statement (AU)

The history of valproate in clinical neuroscience.

The scientific and medical history of valproic acid is relatively long, compared with other frequently used psychopharmacologic agents. Valproic acid was used as an organic solvent in research laboratories for eight decades, until the fortuitous observation of action against pentylenetetrazol-induced convulsions in rodents. Early clinical experience emphasized therapy of absence seizures in primary generalized epilepsies. During two decades of controlled trials in partial-onset and generalized-onset seizures and myoclonus, valproate was established as the prototypical broad-spectrum antiepileptic drug. Anecdotal observations in patients with both epilepsy and migraine headaches who were started on valproate led to prospective, randomized trials that established antimigraine efficacy. Early observations suggested antimanic actions; more than a decade later, controlled clinical trials established significant efficacy of valproate in mania. Antiproliferative effects of valproate were unexpectedly noted during mechanistic studies; two decades later a maintenance adjunctive or chemopreventive role in oncology is being defined. While pharmacokinetic studies appear definitive, completion of comprehensive pharmacodynamic investigations of valproate's biochemical actions and clinical utility is yet to be achieved.

Mood-stabilizers: the archeology of the concept.

OBJECTIVE: To review the history of 'mood-stabilizing' treatments. METHOD: We have reviewed primary source data on the origin of the use of current mood-stabilizers. RESULTS: This historical record on the origins of the mood-stabilizers points to a more ambiguous picture as regards pharmacotherapeutic specificity to bipolar disorders than is commonly conceded. CONCLUSIONS: This review suggests a need for alternative formulations of the concept of a mood-stabilizer. An alternative to the currently dominant paradigm is that these agents have treatment effects, which need to be matched more precisely with patients' constitutional types in order to optimize outcomes.

Pharmacological and therapeutic properties of valproate: a summary after 35 years of clinical experience.

Thirty-five years since its introduction into clinical use, valproate (valproic acid) has become the most widely prescribed antiepileptic drug (AED) worldwide. Its pharmacological effects involve a variety of mechanisms, including increased gamma-aminobutyric acid (GABA)-ergic transmission, reduced release and/or effects of excitatory amino acids, blockade of voltage-gated sodium channels and modulation of dopaminergic and serotoninergic transmission. Valproate is available in different dosage forms for parenteral and oral use. All available oral formulations are almost completely bioavailable, but they differ in dissolution characteristics and absorption rates. In particular, sustained-release formulations are available that minimise fluctuations in serum drug concentrations during a dosing interval and can therefore be given once or twice daily. Valproic acid is about 90% bound to plasma proteins, and the degree of binding decreases with increasing drug concentration within the clinically occurring range. Valproic acid is extensively metabolised by microsomal glucuronide conjugation, mitochondrial beta-oxidation and cytochrome P450-dependent omega-, (omega-1)- and (omega-2)-oxidation. The elimination half-life is in the order of 9 to 18 hours, but shorter values (5 to 12 hours) are observed in patients comedicated with enzyme-inducing agents such as phenytoin, carbamazepine and barbiturates. Valproate itself is devoid of enzyme-inducing properties, but it has the potential of inhibiting drug metabolism and can increase by this mechanism the plasma concentrations of certain coadministered drugs, including phenobarbital (phenobarbitone), lamotrigine and zidovudine. Valproate is a broad spectrum AED, being effective against all seizure types. In patients with newly diagnosed partial seizures (with or without secondary generalisation) and/or primarily generalised tonic-clonic seizures, the efficacy of valproate is comparable to that of phenytoin, carbamazepine and phenobarbital, although in most comparative trials the tolerability of phenobarbital was inferior to that of the other drugs. Valproate is generally regarded as a first-choice agent for most forms of idiopathic and symptomatic generalised epilepsies. Many of these syndromes are associated with multiple seizure types, including tonic-clonic, myoclonic and absence seizures, and prescription of a broad-spectrum drug such as valproate has clear advantages in this situation. A number of reports have also suggested that intravenous valproate could be of value in the treatment of convulsive and nonconvulsive status epilepticus, but further studies are required to establish in more detail the role of the drug in this indication. The most commonly reported adverse effects of valproate include gastrointestinal disturbances, tremor and bodyweight gain. Other notable adverse effects include encephalopathy symptoms (at times associated with hyperammonaemia), platelet disorders, pancreatitis, liver toxicity (with an overall incidence of 1 in 20,000, but a frequency as high as 1 in 600 or 1 in 800 in high-risk groups such as infants below 2 years of age receiving anticonvulsant polytherapy) and teratogenicity, including a 1 to 3% risk of neural tube defects. Some studies have also suggested that menstrual disorders and certain clinical, ultrasound or endocrine manifestations of reproductive system disorders, including polycystic ovary syndrome, may be more common in women treated with valproate than in those treated with other AEDs. However, the precise relevance of the latter findings remains to be evaluated in large, prospective, randomised studies.

Basic pharmacology of valproate: a review after 35 years of clinical use for the treatment of epilepsy.

Since its first marketing as an antiepileptic drug (AED) 35 years ago in France, valproate has become established worldwide as one of the most widely used AEDs in the treatment of both generalised and partial seizures in adults and children. The broad spectrum of antiepileptic efficacy of valproate is reflected in preclinical in vivo and in vitro models, including a variety of animal models of seizures or epilepsy. There is no single mechanism of action of valproate that can completely account for the numerous effects of the drug on neuronal tissue and its broad clinical activity in epilepsy and other brain diseases. In view of the diverse molecular and cellular events that underlie different seizure types, the combination of several neurochemical and neurophysiological mechanisms in a single drug molecule might explain the broad antiepileptic efficacy of valproate. Furthermore, by acting on diverse regional targets thought to be involved in the generation and propagation of seizures, valproate may antagonise epileptic activity at several steps of its organisation. There is now ample experimental evidence that valproate increases turnover of gamma-aminobutyric acid (GABA) and thereby potentiates GABAergic functions in some specific brain regions thought to be involved in the control of seizure generation and propagation. Furthermore, the effect of valproate on neuronal excitation mediated by the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors might be important for its anticonvulsant effects. Acting to alter the balance of inhibition and excitation through multiple mechanisms is clearly an advantage for valproate and probably contributes to its broad spectrum of clinical effects. Although the GABAergic potentiation and glutamate/NMDA inhibition could be a likely explanation for the anticonvulsant action on focal and generalised convulsive seizures, they do not explain the effect of valproate on nonconvulsive seizures, such as absences. In this respect, the reduction of gamma-hydroxybutyrate (GHB) release reported for valproate could be of interest, because GHB has been suggested to play a critical role in the modulation of absence seizures. Although it is often proposed that blockade of voltage-dependent sodium currents is an important mechanism of antiepileptic action of valproate, the exact role played by this mechanism of action at therapeutically relevant concentrations in the mammalian brain is not clearly elucidated. By the experimental observations summarised in this review, most clinical effects of valproate can be explained, although much remains to be learned at a number of different levels about the mechanisms of action of valproate. In view of the advances in molecular neurobiology and neuroscience, future studies will undoubtedly further our understanding of the mechanisms of action of valproate.

[Brief history of the development of valproate in bipolar disorders]. / Historique du développement du valproate dans les troubles bipolaires.

The anticonvulsant properties of N-dipropylacetic acid (valproic acid) were discovered in 1967 by Meunier and Carraz. It very soon became widely used in epilepsy, generally in the form of sodium valproate. Divalproate, an equimolar combination of valproic acid and sodium valproate has been available in the United States for this indication since 1983. The development of this drug for use in bipolar disorders occurred in two stages. Antimanic and prophylactic activity was demonstrated for valpromide, a primary amide of valproic acid (Lambert et al., 1968-71). The preliminary studies conducted by Lambert were not repeated outside France and it was only much later that the efficacy of derivatives of valproic acid in bipolar disorders was demonstrated in studies undertaken in Germany with sodium valproate (Enrich and Von Zerssen, 1980-85), and then in the USA with divalproate in the last decade. The majority of controlled studies were performed with divalproate and demonstrated the efficacy of this drug in monotherapy during manic episodes (Pope et al., 1991) (Bowden et al, 1994), and divalproate was approved by the FDA in 1995 in this indication. The results of the study by Bowden and the findings of other open studies suggest a wider spectrum of activity for divalproate than for lithium with a good efficacy profile in subtypes of mania in which the effects of lithium are mediocre: dysphoric mania, rapid cycling mania and forms of mania secondary to organic brain disease. The prospective studies by Puzynski and Klosiewicz (1984) and by Lambert and Venaud (1992) demonstrated the prophylactic activity of valpromide, with slightly greater efficacy being noted against manic episodes than against depressive episodes. The study by Bowden et al. (2000) shows that good efficacy of divalproate in acute manic episodes in a given patient may be predictive of efficacy of the drug in maintenance therapy. The field of bipolar disorders currently appears much wider and more heterogeneous than has long been held. Current therapeutic strategy is dominated by thymoregulators. In such long-term therapy where poor compliance constitutes a risk factor for treatment failure, use of valproate (valpromide, divalproate) has the twin advantage of being easy to manage and well tolerated in the long-term. During coadministration of thymoregulators, which is often necessary due to their limited individual efficacy, general consensus exists regarding the therapeutic value of combined divalproate and lithium.