30 years of second-generation antiseizure medications: impact and future perspectives.

Since 1989, 18 second-generation antiseizure medications have reached the market, resulting in a greatly increased range of treatment options for patients and prescribers. 30 years have passed and now is the time for an appraisal of the effect of these medications on clinical outcomes. Every antiseizure medication needs to be assessed individually, but overall second-generation drugs are less likely to cause pharmacokinetic interactions than their older counterparts. Some second-generation antiseizure medications have shown advantages in tolerability and safety, particularly in the treatment of older patients and women of childbearing potential. Disappointingly, however, none of these medications appear to be more efficacious than first-generation antiseizure medications, highlighting the need for novel strategies in epilepsy drug development. Although second-generation antiseizure medications have not substantially reduced the proportion of patients with pharmacoresistant epilepsy, their availability has enabled more opportunities to tailor treatment choice to the characteristics of the individual.

Antiepileptic drugs: evolution of our knowledge and changes in drug trials.

Clinical trials provide the evidence needed for rational use of medicines. The evolution of drug trials follows largely the evolution of regulatory requirements. This article summarizes methodological changes in antiepileptic drug trials and associated advances in knowledge starting from 1938, the year phenytoin was introduced and also the year when evidence of safety was made a requirement for the marketing of medicines in the United States. The first period (1938-1969) saw the introduction of over 20 new drugs for epilepsy, many of which did not withstand the test of time. Only few well controlled trials were completed in that period and trial designs were generally suboptimal due to methodological constraints. The intermediate period (1970-1988) did not see the introduction of any major new medication, but important therapeutic advances took place due to improved understanding of the properties of available drugs. The value of therapeutic drug monitoring and monotherapy were recognized during the intermediate period, which also saw major improvements in trial methodology. The last period (1989-2019) was dominated by the introduction of second-generation drugs, and further evolution in the design of monotherapy and adjunctive-therapy trials. The expansion of the pharmacological armamentarium has improved opportunities for tailoring drug treatment to the characteristics of the individual. However, there is still inadequate evidence from controlled trials to guide treatment selection for most epilepsy syndromes, particularly in children. Second-generation drugs had a very modest impact on drug resistance, and a change in paradigm for drug discovery and development is needed, focusing on treatments that target the causes and mechanisms of epilepsy rather than its symptoms. Testing potential disease modifying agents will require innovative trial designs and novel endpoints, and will hopefully lead to introduction of safer and more effective therapies.

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.

Medical Cannabis: A plurimillennial history of an evergreen.

The history of Cannabis goes along that of humankind, as speculated based on geographical and evolutionary models together with historic data collected to date. Its medical use is several thousand years old, as attested both by archeobotanical evidence of Cannabis remains and written records found in ancient texts from the sacred Vedic foundational texts of Ayurvedic medicine (about 800 before current era [BCE]) to the first known Pharmacopoea, the Chinese "Shen Nung Pen Ts'ao Ching" (1 century BCE). In this paper, we retrace the history of Cannabis traveling through the key stages of its diffusion among the most important ancient cultures up to our days, when we are facing a renaissance of its medical employment. We report through the centuries evidence of its use in numerous pathologic conditions especially for its anti-inflammatory, antiseptic, and anticonvulsing properties that support the requirement to direct our present research efforts into the definitive understanding of its efficacy.

Phenytoin: 80 years young, from epilepsy to breast cancer, a remarkable molecule with multiple modes of action.

In 1908 phenytoin (5,5-diphenylhydantoin) was first synthesized as a barbiturate derivative in Germany by professor Heinrich Biltz (1865-1943) and subsequently resynthesized by an American chemist of the pharmaceutical company Parke-Davis in 1923 in Detroit. Screening phenytoin did not reveal comparable sedative side effects as barbiturates and, thus, Parke-Davis discarded this compound as a useful drug. In 1936, phenytoin's anticonvulsive properties were identified via a new animal model for convulsive disorders, developed by Putnam and Merritt, who also evaluated its clinical value in a number of patients in the period 1937-1940. For many diseases, mechanism of action of phenytoin remains obscure. The voltage-gated sodium channel was and is generally regarded as the main target to explain phenytoin's activity as an anticonvulsant and an anti-arrhythmic drug. This target, however, does not explain many of the other clinical properties of phenytoin. We will explore a number of original articles on phenytoin published in its 80 years history and give extra attention to the various hypothesis and experiments done to elucidate its mechanisms of action. Phenytoin has been explored in over 100 different disorders; the last two promising indications tested in the clinic are breast cancer and optic neuritis. Most probably, there are multiple targets active for these various disorders, and the insight into which targets are relevant is still very incomplete. It is remarkable that many pharmacological studies tested one dose only, mostly 50 or 100 µM, doses which most probably are higher than the non-plasma bound phenytoin plasma levels obtained during treatment.

Drug development for refractory epilepsy: The past 25 years and beyond.

Despite the exponential growth of approved antiepileptic drugs (AEDs) over the past 25 years, epilepsy remains uncontrolled in approximately a third of patients. This article summarises the clinical trials and properties of the AEDs developed over this period, and reviews the pre-clinical and clinical development paradigms of modern AEDs. We discuss possible reasons for the apparent failure to develop more efficacious compounds. We also review the current regulatory frameworks for drug approval in the United States and Europe, and the changes on the horizon. Encouragingly, better elucidation of the pathophysiological mechanisms underpinning pharmacoresistance and the epilepsies by recent research has enabled a revised approach to the development of more promising therapies. A new era of pharmacological treatment for epilepsy appears imminent. Future research in pharmacotherapy for drug-resistant epilepsy will be advanced through concerted effort between scientists, clinicians, and the industry.

Thirty Years of Orphan Drug Legislation and the Development of Drugs to Treat Rare Seizure Conditions: A Cross Sectional Analysis.

BACKGROUND: Epilepsy is a serious chronic health condition with a high morbidity impairing the life of patients and afflicted families. Many epileptic conditions, especially those affecting children, are rare disorders generating an urgent medical need for more efficacious therapy options. Therefore, we assessed the output of the US and European orphan drug legislations. METHODS: Quantitative analysis of the FDA and EMA databases for orphan drug designations according to STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) criteria. RESULTS: Within the US Orphan Drug Act 40 designations were granted delivering nine approvals, i.e. clobazam, diazepam viscous solution for rectal administration, felbamate, fosphenytoin, lamotrigine, repository corticotropin, rufinamide, topiramate, and vigabatrin. Since 2000 the EMA granted six orphan drug designations whereof two compounds were approved, i.e. rufinamide and stiripentol. In the US, two orphan drug designations were withdrawn. Orphan drugs were approved for conditions including Lennox-Gastaut syndrome, infantile spasms, Dravet syndrome, and status epilepticus. Comparing time to approval for rufinamide, which was approved in the US and the EU to treat rare seizure conditions, the process seems faster in the EU (2.2 years) than in the US (4.3 years). CONCLUSION: Orphan drug development in the US and in the EU delivered only few molecular entities to treat rare seizure disorders. The development programs focused on already approved antiepileptic drugs or alternative pharmaceutical formulations. Most orphan drugs approved in the US are not approved in the EU to treat rare seizures although some were introduced after 2000 when the EU adopted the Orphan Drug Regulation.

[The I.G. Farben laboratory at the Günzburg mental hospital. Epilepsy research during the NS-regime and the postwar period]. / Das Laboratorium der I.G. Farben an der Heil- und Pflegeanstalt Günzburg. Epilepsieforschung in der NS-Zeit und den Nachkriegsjahren.

The purpose of this study is to evaluate the activities of the I.G. Farben laboratory at the former "Heil- und Pflegeanstalt" Günzburg. This laboratory was established to test the newly developed epilepsy drug "Citrullamon" and its derivatives. Specifically, the type and manner of the various experiments were examined to determine whether the suspicions of unethical human experimentation could be identified. The commercial and medical activities between I.G. Farben and the Heil- und Pflegeanstalt, including the specific roles of the senior physician Wilhelm Leinisch and the I.G. Farben chemist Arno Grosse, are reviewed.

[On the history of barbiturates]. / Pionerer bag barbituraterne.

Throughout the history of humanity, numerous therapeutic agents have been employed for their sedative and hypnotic properties such as opium, henbane (Hyoscyamus niger) and deadly nightshade (Atropa belladonna), but also alcohol and wine. In the 19th century potassium bromide was introduced as a sedative - and antiepileptic drug and chloral hydrate as sedative-hypnotics. A new era was reached by the introduction of barbiturates. The story started with the chemist Adolf von Baeyer. His breakthrough in the synthesis of new agents as barbituric acid and indigo and his education of young chemists was of great importance for the science of organic chemistry and the development of the dye and medicine industry in the late 19th century. The next important step was the development of barbiturates. The pioneers were Josef von Mering and Emil Fischer. Using the Grimaux-method they synthesized various barbiturates. It was von Mering who got the idea of introducing ethyl groups in the inactive barbituric acid to obtain sedatives, but the synthesis was succeeded by the chemist Emil Fischer. Experiments with dogs clearly showed sedative and hypnotic effect of the barbiturates and the oral administration of barbital (Veronal) confirmed the effect in humans. Barbital was commercialized in 1903 and in 1911 phenobarbital (Luminal) was introduced in the clinic, and this drug showed hypnotic and antiepileptic effects. Thereafter a lot of new barbiturates appeared. Dangerous properties of the drugs were recognized as abuse, addiction, and poisoning. An optimum treatment of acute barbiturate intoxication was obtained by the "Scandinavian method", which was developed in the Poison Centre of the Bispebjerg Hospital in Copenhagen. The centre was established by Carl Clemmesen in 1949 and the intensive care treatment reduced the mortality of the admitted persons from 20% to less than 2%. To-day only a few barbiturates are used in connection with anaesthesia and for the treatment of epilepsy, and chemists are focusing on drugs with more selective effects.

Novel approaches to anticonvulsant drug discovery.

INTRODUCTION: The history of epilepsy dates back to 2000 BC. Yet, it was not until 1912 that the activity of the first antiepileptic, phenobarbital was discovered by accident. After this discovery, the next antiepileptic drugs to be discovered (phenytoin and primidone) were based on the phenobarbital's structure. Then, in 1960, carbamazepine was developed empirically, while in 1962, valproate demonstrated anticonvulsant activity against experimental seizures. The next antiepileptic drugs synthesized were either modifications of the existing drugs (such as oxcarbazepine and pregabalin) or completely novel chemical structures (lacosamide, perampanel and retigabine). AREAS COVERED: The present paper briefly refers to the history of epilepsy and development of antiepileptic drugs. Further, the paper provides a discussion on the antiepileptogenic effects of antiepileptic drugs in terms of the constant percentage of epileptic patients with refractory seizures. The authors also review the likely factors involved in the false refractoriness (such as through the use of caffeine-containing beverages and smoking). Finally, the authors consider future directions in the search of novel antiepileptic drugs. EXPERT OPINION: In spite of the considerable number of newer antiepileptic drugs, the number of drug-resistant epileptic patients remains unchanged. This may be rather an indication of the suitability of the currently available discovery procedures for effective antiepileptic drugs in the whole population of epileptic patients. The authors, however, believe that it is likely that models of mimic chronic epilepsy will help bridge the gaps and aid in the discovery of novel antiepileptic drugs - ones that can effectively modify the course of the disease.

The historical evolution of, and the paradigms shifts in, the therapy of convulsive status epilepticus over the past 150 years.

The evolution of the treatment of convulsive status epilepticus since the mid- nineteenth century is outlined. Therapy has been advanced not only by the use of new drugs, but also by advances in the approach to therapy. The major pharmacologic developments were the introductions of bromide, anesthetics, barbiturate, phenytoin, paraldehyde, chlormethiazole, and the benzodiazepines. Throughout this period, the emphasis of therapy was on "sedation" and anesthesia, and the development of technologies for safe anesthesia in the postwar years were an important step. Since 1970, changes to the approach to therapy have been more important than any pharmacologic advance, and it is only recently that new drugs have been introduced into the therapy of status epilepticus. We may now be on the threshold of significant new paradigm shifts.

Treating epilepsy in Italy between XIX and XX century.

Epilepsy is a neurological disorder which has been recognized since antiquity. This paper evaluates the prophylactic and therapeutic remedies used by folk medicine to cure epilepsy in Italy. The data has been collected by reviewing written sources of physicians, ethnographers, folklorists between the late nineteenth and mid twentieth century. This approach leads to unearthing of 78 heterogeneous healing methods that have been divided into 16 (20%) magical, 20 (26%) religious and 42 (54%) natural remedies. The latter has been subdivided into 18 (43%) animal remedies, 17 (40%) plant remedies and 7 (17%) other remedies. Religious and magical remedies were used with the conviction that they would be able to provide recovery from epilepsy and to ward off evil spirits which had taken possession of the sick. Interestingly, the herbal remedies highlighted 12 (70%) plants that play or might play an important role with respect to the mechanisms that generate the epileptic seizures. This leads us to reconsider the historical significance of folk medicine, too often it is underestimated owing to its use of ineffective remedies, born of incompetence and superstition.

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.