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.

How phenobarbital revolutionized epilepsy therapy: the story of phenobarbital therapy in epilepsy in the last 100 years.

Phenobarbital (phenobarbitone) was first used as an antiepileptic drug 100 years ago, in 1912. This article tells the story of the discovery of its antiepileptic action, its early development, and the subsequent course of its clinical use over the 100-year period. The side effects, pharmacokinetics, and misuse of barbiturates are considered, along with the more recent clinical trials and the drug's current clinical utilization. The introduction of controlled drug regulations, the comparative cost of phenobarbital, and its inclusion on the World Health Organization (WHO) essential drug list are discussed. It is one of the few drugs on the formulary in 1912 that is still listed today, and remarkably its efficacy in epilepsy has not been significantly bettered. The current recommendation by the WHO is that phenobarbital should be offered as the first option for therapy for convulsive epilepsy in adults and children if availability can be ensured. This is rated as a strong recommendation because of the proven efficacy and low cost of phenobarbital, and despite its perceived side-effect profile and the practical problems of access. Whether this recommendation puts "a hierarchy on the brain," as has been suggested, is arguable. Much still needs to be learned about the drug's effects, and the issues raised by phenobarbital have lessons for all antiepileptic drug therapy.

Drug treatment of epilepsy in the century of the ILAE: the first 50 years, 1909-1958.

This paper provides a review of the drug treatment of epilepsy from 1909, the year of the foundation of the International League Against Epilepsy (ILAE), to 1958. It was during this period that modern approaches to the medicinal therapy of epilepsy were formulated and many new drugs were introduced. Of these, both phenytoin and phenobarbital continue to be widely used today. This was the period when scientific screening was also introduced into drug discovery. The leading figures in the ILAE played an important role in guiding the evolution of the treatment of epilepsy during this period.

Clinical experience with new antiepileptic drugs: antiepileptic drugs in Europe.

The use of antiepileptic drugs (AEDs), singly and in combination, has been marked by variation among European countries and by a slow progress toward a standard of care that is still far from uniform. Phenobarbital, phenytoin, trimethadione, and primidone, given in various combinations, were the predominant agents used in the first half of this century. Prescribing habits differed among the Latin countries, the United Kingdom, and Scandinavia, based on local trends, divergent teaching philosophies of medical schools, and the medical specialty of the prescribing physician. The advent of carbamazepine and valproate, in the early 1960s, changed European prescribing habits. Despite early fears regarding bone marrow toxicity, carbamazepine was found to be superior for treatment of complex partial seizures. Valproate, when the proper therapeutic dosage was belatedly realized, was seen as a superior treatment for generalized and partial epilepsies. Both agents are now considered first-line treatments for these seizure types. The role of the benzodiazepines as adjunctive anticonvulsant therapy remains controversial because of concerns about neurotoxicity and patient tolerance. The number of AEDs marketed in Europe has grown dramatically in the past decade, with agents such as felbamate, gabapentin, lamotrigine, and tiagabine having been approved as either adjunctive or sole therapy. However, not all new agents are available in each European country, and some variation in prescribing persists.

[Migrane treatment in the Netherlands in the early twentieth century]. / De behandeling van migraine in Nederland in het begin van de 20e eeuw.

The treatment of migraine in the Netherlands underwent important changes in the beginning of the 20th century. Several factors played a role, including the development of analgesics (acetylsalicylic acid, phenacetin, and fampridine++) at the end of the 19th century. The introduction of phenobarbital for the treatment of epilepsy in 1912 resulted in prescription of this drug for migraine, because of the supposed similarities between both afflictions. Although ergotamine had been reported for the treatment of headache at the end of the 19th century and been recommended again during the 1920s, it appeared in the Dutch literature only at the end of the 1930s. Research abroad showed this drug to have vasoconstrictive properties in migraine, again confirming the vasogenic origin of the affliction. This is striking as vasodilating drugs had been prescribed for several years. The non-medical treatment largely remained as previously, notably the prescription of diets. The relation between migraine and anaphylaxis, based on research by the French school, was also investigated in the Netherlands and resulted in the prescription of diets to immunize against the proteins involved.