Felbamate

Felbamate (FBM) is a potent nonsedative anticonvulsant whose clinical effect may be related to the inhibition of N-methyl-D-aspartate (NMDA) .

The rise and fall of felbamate as a treatment for partial epilepsy--aplastic anemia and hepatic failure to blame?[Pubmed:26566191]

Expert Rev Neurother. 2015;15(12):1373-5.

Felbamate has been approved for refractory partial seizures since the early nineties. Due to safety concerns regarding its use, namely, in aplastic anemia and hepatic failure, Felbamate's use has been restricted and a 'Black Box' warning has been inserted. Nonetheless, it is a useful drug in refractory cases of partial epilepsy. There are certain precautions which can prevent and minimize the serious idiosyncratic reactions associated with Felbamate, thereby providing an option in refractory cases where no other drug works.

Evaluating the safety and efficacy of felbamate in the context of a black box warning: A single center experience.[Pubmed:26828692]

Epilepsy Behav. 2016 Mar;56:50-3.

INTRODUCTION: Felbamate was approved in 1993 to treat partial seizures with and without secondary generalization in adults and in Lennox-Gastaut Syndrome in children. Its use was later restricted when rare but fatal cases of aplastic anemia and hepatic failure were identified. METHODS: This single center analysis retrospectively evaluated the safety and efficacy of Felbamate in a cohort of children, adolescents, and adults with epilepsy. RESULTS: A chart review identified 103 patients taking Felbamate. The range of Felbamate dose was 300-4500 mg (mean: 1800 +/- 900 mg). The duration of therapy ranged from 1 month to 20 years (mean duration: 35 +/- 45 months). Eighteen (17.5%) subjects experienced adverse events including insomnia, nausea, vomiting, decreased appetite, weight loss, gastric discomfort, diarrhea, mood and behavioral problems, high blood pressure, headache, and elevated liver enzymes. Out of these, 6 (5.9%) patients discontinued the therapy. No hepatic failure or agranulocytosis was observed. Fifty-nine (57.72%) patients achieved >/= 50% reduction in seizure frequency, and 30 (29.12%) patients achieved seizure freedom. CONCLUSIONS: These findings suggest that Felbamate is safe, well tolerated, and effective in treatment of various types of epilepsy syndromes.

A Potential Role for Felbamate in TSC- and NF1-Related Epilepsy: A Case Report and Review of the Literature.[Pubmed:26579319]

Case Rep Neurol Med. 2015;2015:960746.

A 15-year-old girl with maternal inheritance of neurofibromatosis type 1 (NF1) and paternal inheritance of tuberous sclerosis complex (TSC) developed intractable epilepsy at age 5. Her seizures were refractory to adequate doses of four antiepileptic medications until Felbamate was initiated at age 7. She has since remained seizure-free on Felbamate monotherapy. Although Felbamate has multiple mechanisms of action, it is thought to have its most potent antiepileptic effects through inhibition of the N-methyl-D-aspartate receptor (NMDAR). Previous studies have shown that the NMDAR is altered in varying epilepsy syndromes and notably in the cortical tubers found in TSC. The aim of this paper is to examine how Felbamate monotherapy was able to achieve such robust antiepileptic effects in a unique patient and possibly offer a novel therapeutic approach to patients suffering from TSC- and NF-related epilepsy.

Successful Treatment of Electrographic Status Epilepticus of Sleep With Felbamate in a Patient With SLC9A6 Mutation.[Pubmed:26421989]

Pediatr Neurol. 2015 Dec;53(6):527-31.

BACKGROUND: Mutations of SLC9A6 may cause an X-linked clinical syndrome first described by Christianson in 1999 in which affected males exhibited profound intellectual disability, autism, drug-resistant epilepsy, ophthalmoplegia, mild craniofacial dysmorphism, microcephaly, and ataxia. METHODS: We describe a child with an SLC9A6 mutation and an electroencephalographic pattern consistent with electrographic status epilepticus of sleep. RESULTS: Our patient's electrographic status epilepticus of sleep resolved after treatment with Felbamate. Following treatment, he remained seizure-free but did not make significant or lasting gains in language. CONCLUSION: Our report extends the clinical epilepsy phenotype in children with SLC9A6 mutations to include electrographic status epilepticus of sleep. In addition, Felbamate was an effective treatment for electrographic status epilepticus of sleep in our patient.

Selective antagonism of the anticonvulsant effects of felbamate by glycine.[Pubmed:8050461]

Eur J Pharmacol. 1994 Apr 21;256(2):R9-10.

Glycine blocked the anticonvulsant effects of Felbamate on electroshock- and NMDA-induced seizures in mice. In contrast to its effects on Felbamate, glycine either potentiated or had no effect on the anticonvulsant actions of phenytoin, valproate, carbamazepine and phenobarbital on electroshock seizures in mice. The data support that the glycine-Felbamate blockade is a specific interaction. Felbamate is likely to be the first clinically available anticonvulsant drug that acts through this unique mechanism.

Excitatory amino acid neurotransmission through both NMDA and non-NMDA receptors is involved in the anticonvulsant activity of felbamate in DBA/2 mice.[Pubmed:7529182]

Eur J Pharmacol. 1994 Sep 1;262(1-2):11-9.

The anticonvulsant activity of Felbamate against sound-induced seizures was studied in the DBA/2 mouse model. Felbamate (10-300 mg/kg, i.p.) produced dose-dependent effects with ED50 values for the suppression of tonic, clonic and wild running phases of 23.1, 48.8 and 114.6 mg/kg, respectively. Felbamate also protected DBA/2 mice from N-methyl-D-aspartate (NMDA)-induced seizures with ED50 values of 12.1 and 29 mg/kg for tonus and clonus, respectively. Pretreatment with glycine, an agonist to the glycine/NMDA receptors, shifted the dose-response effect of Felbamate to the right (ED50 = 56.8 against tonus and 94.8 mg/kg versus clonus). Similarly, D-serine, an agonist at the glycine site, shifted the ED50 of Felbamate against the tonic component of audiogenic seizures from 23.1 to 78.1, and that against clonus from 48.8 to 90.3 mg/kg. Felbamate was also potent to prevent seizures induced by administration of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), an AMPA/kainate receptor agonist (ED50 = 11.8 and 20.9 mg/kg, against tonus and clonus, respectively). The data indicate that Felbamate is an effective anticonvulsant drug in the genetic model of seizure-prone DBA/2 mice. Our findings suggest that the anticonvulsant properties of Felbamate depend upon its interaction with neurotransmission mediated by both the glycine/NMDA and the AMPA/kainate receptor complex.

Felbamate antagonizes isoniazid- and FG 7142-induced reduction of GABAA receptor function in mouse brain.[Pubmed:7875235]

Eur J Pharmacol. 1994 Nov 24;265(3):185-8.

Injection of the antiepileptic drug, Felbamate (2-phenyl-1,3-propanediol dicarbamate), into mice reduced in a dose-dependent manner (150-300 mg/kg i.p.) the isoniazid (200 mg/kg s.c.)-induced increase in ex vivo binding of t-[35S]butylbicyclophosphorothionate ([35S]TBPS) to cerebral cortical and hippocampal membranes. The same doses of Felbamate reduced significantly the number of mice exhibiting isoniazid-induced seizures. A dose of Felbamate (50 mg/kg) ineffective in isoniazid-treated mice completely antagonized the increase of [35S]TBPS binding elicited by FG 7142 (N-methyl-beta-carboline-3-carboxamide), a benzodiazepine receptor inverse agonist. The above effects of Felbamate resembled those of diazepam. Accordingly, the combination of ineffective doses of Felbamate (50 mg/kg) and diazepam (0.2 mg/kg) elicited a marked decrease of [35S]TBPS binding. The results indicate that facilitation of gamma-aminobutyric acid type A (GABAA) receptor function may play a role in the anticonvulsant action of Felbamate.

Mechanisms of action of new antiepileptic drugs: rational design and serendipitous findings.[Pubmed:7886818]

Trends Pharmacol Sci. 1994 Dec;15(12):456-63.

After years without any major breakthroughs in the treatment of epilepsy disorders, a new wave of antiepileptic drugs have become available to clinicians. Felbamate, gabapentin, lamotrigine and vigabatrin are among the most promising of this new generation of drugs and, when used as add-on therapy, provide some improvement in a significant number of patients suffering from previously refractory epilepsy whilst exhibiting a lower risk of unwanted side-effects than traditional antiepileptic drugs. In this article, Neil Upton reviews the recent discoveries that suggest these four new agents exert their antiepileptic properties by acting through diverse and often novel mechanisms, some of which are by design, and some of which are by chance. Also highlighted are examples of the most innovative mechanistic approaches currently being adopted to produce the next generation of antiepileptic drugs.

Felbamate (W-554) is a potent nonsedative anticonvulsant whose clinical effect may be related to the inhibition of N-methyl-D-aspartate (NMDA).

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