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A novel high sensitivity HPLC assay for topiramate, using 4-chloro-7-nitrobenzofurazan as pre-column fluorescence derivatizing agent.

A new, sensitive and simple high-performance liquid chromatographic method for analysis of topiramate, an antiepileptic agent, using 4-chloro-7-nitrobenzofurazan as pre-column derivatization agent is described. Following liquid-liquid extraction of topiramate and an internal standard (amlodipine) from human serum, derivatization of the drugs was performed by the labeling agent in the presence of dichloromethane, methanol, acetonitrile and borate buffer (0.05 M; pH 10.6). A mixture of sodium phosphate buffer (0.05 M; pH 2.4): methanol (35:65 v/v) was eluted as mobile phase and chromatographic separation was achieved using a Shimpack CLC-C18 (150 x 4.6 mm) column. In this method the limit of quantification of 0.01 microg/mL was obtained and the procedure was validated over the concentration range of 0.01 to 12.8 microg/mL. No interferences were found from commonly co-administrated antiepileptic drugs including phenytoin, phenobarbital carbamazepine, lamotrigine, zonisamide, primidone, gabapentin, vigabatrin, and ethosuximide. The analysis performance was carried-out in terms of specificity, sensitivity, linearity, precision, accuracy and stability and the method was shown to be accurate, with intra-day and inter-day accuracy from -3.4 to 10% and precise, with intra-day and inter-day precision from 1.1 to 18%.

Anticonvulsants↗

Comparison of the effects of anticonvulsant drugs with diverse mechanisms of action in the formalin test in rats.

The purpose of the present studies was to compare anticonvulsant drugs with diverse mechanisms of action in a persistent pain model, the formalin test. In addition, the anticonvulsant effects of the compounds were determined in the threshold electroshock tonic seizure test and the 6-Hz limbic seizure test. The effects of the compounds were also determined on locomotor activity. Carbamazepine, oxcarbazepine, lamotrigine, gabapentin and ethosuximide all produced statistically significant analgesic effects in the formalin test whereas phenytoin, topiramate, zonisamide, phenobarbital, tiagabine, valproate and levetiracetam did not. All compounds were anticonvulsant. In addition, morphine and phenobarbital increased locomotor activity while ethosuximide had no effect and all other compounds decreased locomotor activity. For those compounds that were analgesic, the doses required to produce analgesia were larger in magnitude than the anticonvulsant ED50 values in the threshold electroshock and 6-Hz tests, as well as larger than doses that altered locomotor activity. The present results demonstrate that the anticonvulsant and analgesic effects of clinically used antiepileptic drugs do not necessarily correlate and therefore suggest that the anticonvulsant and analgesic efficacy of these drugs may be due to different pharmacologic mechanisms.

Analgesics, Opioid↗

Use of antiepileptic drugs for nonepileptic conditions: psychiatric disorders and chronic pain.

Antiepileptic drugs (AEDs) are commonly utilized for nonepileptic conditions, including various psychiatric disorders and pain syndromes. Evidence for their benefit in these nonepileptic conditions varies widely among different drugs, but there is, in general, a paucity of published multicenter randomized double-blind trials. Variable levels of evidence suggest that lamotrigine and the vagal nerve stimulator have antidepressant properties. Carbamazepine, valproate, lamotrigine, and oxcarbazepine appear to have mood stabilizing properties while gabapentin, pregabalin, and tiagabine have anxiolytic benefits. Barbiturates, topiramate, and possibly phenytoin may precipitate or exacerbate depression. Underlying depression and anxiety symptoms may be exacerbated by levetiracetam, while psychotic symptoms have rarely been reported with topiramate, levetiracetam, and zonisamide. Pregabalin, gabapentin, carbamazepine, and oxcarbazepine have been used to treat neuropathic pain such as postherpetic neuralgia, and diabetic polyneuropathy. Topiramate and divalproex sodium have utility in the prophylaxis or acute treatment of migraine. Further rigorous studies are needed to clarify the utility of AEDs in nonepileptic conditions.

Anticonvulsants↗

Discovery of antiepileptic drugs.

Since 1993, the Anticonvulsant Drug Development Program has contributed to the successful development of nine clinically effective drugs for the symptomatic treatment of epilepsy. These include felbamate (1993), gabapentin (1994), lamotrigine (1994), fosphenytoin (1996), topiramate (1996), tiagabine (1997), levetiracetam (1999), zonisamide (2000), and oxcarbazepine (2000). Despite the apparent success of the current discovery process, a significant need persists for more efficacious and less toxic antiepileptic drugs (AEDs). This is particularly true for patients whose seizures remain refractory to the currently available AEDs. This chapter will review the current process for AED discovery employed by the Anticonvulsant Drug Development Program at the University of Utah and other laboratories working toward the common goal of discovering better therapeutic options for patients living with epilepsy. It will discuss some of the inherent advantages and limitations of the primary animal models employed, while offering insight into potential future directions as we seek to better understand the pathophysiology underlying acquired epilepsy, therapy resistance, and epileptogenesis.

Animals↗

Psychiatric and behavioral side effects of the newer antiepileptic drugs in adults with epilepsy.

OBJECTIVE: Psychiatric/behavioral side effects (PSEs) are common in patients taking antiepileptic drugs (AEDs). The objective of the study described here was to compare the PSE profiles of the newer AEDs. METHODS: We examined the charts of 1394 adult outpatients seen at the Columbia Comprehensive Epilepsy Center who had taken one of the newer AEDs. We compared the rate of AED-related PSEs in patients newly started on the newer AEDs both before and after controlling for non-AED predictors of PSEs. RESULTS: Overall, 221 of 1394 (16%) patients experienced PSEs. The average rate of AED-related PSEs for a single AED was 8.4%, with 6.1% resulting in dosage change and 4.3% resulting in AED discontinuation. Significantly fewer PSEs were attributed to gabapentin (n=160, 0.6% incidence, P<0.001) and lamotrigine (n=547, 4.8% incidence, P<0.001), and significantly more PSEs were attributed to levetiracetam (n=521, 15.7% incidence, P<0.001; 8.8% discontinued LEV because of PSEs). Vigabatrin, felbamate, and oxcarbazepine were associated with similarly low rates of PSEs in many analyses but with fewer of patients. Tiagabine was associated with high PSE rates (similar to those for levetiracetam), but was used much less commonly at our center. Intermediate rates of PSEs were attributed to topiramate and zonisamide (both nonsignificant). Psychiatric history was the most significant nondrug predictor of AED-related PSEs (PSEs occurred in 23% of patients with a psychiatric history vs 12% of patients without such a history, P<0.001). The relative rates of AED-related PSEs were similar when controlling for non-AED predictors and when analyzing only patients on monotherapy. CONCLUSIONS: There are significant differences between the newer AEDs in terms of their PSE profiles. Patients taking levetiracetan experience significantly more PSEs than average, and patients taking gabapentin and lamotrigine experience significantly fewer PSEs. Even with the medication with the highest rate of PSEs (levetiracetam), less than 10% of patients discontinued it because of PSEs. A past psychiatric condition is the most significant nondrug predictor of AED-related PSEs.

Adult↗

Infertility treatment in women with epilepsy: A systematic review.

BACKGROUND: The impact of assisted reproductive technologies (ART) on seizure control in women with epilepsy remains incompletely understood. METHODS: A systematic review was conducted according to PRISMA guidelines. EMBASE, MEDLINE, CINAHL, Scopus, and the Cochrane Library were searched from inception to March 2025. Eligible studies included observational studies and case-based reports involving women undergoing infertility treatment. RESULTS: A total of 1216 publications were identified, of which four studies met the inclusion criteria, including case reports, a case series, and a cohort study. These studies included 16 women aged 25-46&#xa0;years undergoing infertility treatment, all but one of whom had epilepsy. Interventions involved in vitro fertilization (IVF), ovulation induction, and hormonal therapies. Patients were treated with a range of antiseizure medications (ASMs), including carbamazepine, clobazam, lamotrigine, levetiracetam, oxcarbazepine, valproate, and zonisamide, either as monotherapy or in combination. Seizure frequency was generally stable, with most patients maintaining baseline seizure control. Seizure exacerbations were uncommon and primarily associated with hormonal therapy and reduced ASM levels, particularly reduced lamotrigine levels. Reported events included breakthrough seizures in the setting of decreased lamotrigine concentrations, seizure clusters associated with follitropin beta, and a new-onset seizure following dehydroepiandrosterone exposure. Across studies, multiple ART attempts resulted in live births with different ASM regimens, as well as in patients not receiving ASMs. CONCLUSION: Available evidence suggests that ART is feasible in women with epilepsy, with most patients maintaining stable seizure control. Hormonal therapy may affect ASM pharmacokinetics and seizure threshold, thereby warranting close monitoring. Larger prospective studies are needed to better define ASM-specific effects and optimize care.

Humans↗

Pharmacologic agents for the treatment of acute bipolar mania.

The knowledge base regarding the medical treatment of acute bipolar mania is rapidly expanding. Information about agents with established antimanic properties is increasing, and more agents with putative antimanic properties are being identified. We first review the controlled studies supporting the efficacy of the established antimanic agents lithium, valproate, and carbamazepine and standard antipsychotics. We then review available research on two important classes of drugs that are emerging as potential treatments for acute mania: the novel antipsychotics, which include clozapine, olanzapine, quetiapine, risperidone, and ziprasidone, and the new antiepileptics, which include gabapentin, lamotrigine, oxcarbazepine, tiagabine, topiramate, and zonisamide. We conclude that although controlled data are accumulating to support the efficacy of several atypical antipsychotics in the treatment of acute bipolar mania, particularly olanzapine, ziprasidone, and risperidone, the novel antiepileptics need more extensive study before it can be concluded that any of them possess specific antimanic properties. We also conclude that as the medical options for acute bipolar mania expand, treatment guidelines must remain both evidence based and flexible, so that they represent cutting edge medical science yet can be tailored to the specific needs of individual patients.

Acute Disease↗

Characteristics of flurothyl-induced seizures and the effect of antiepileptic drugs on flurothyl-induced seizures in Mongolian gerbils.

We investigated the characteristics of the flurothyl-induced seizures and the effects of antiepileptic drugs on the flurothyl-induced seizure model in a previously untested Mongolian gerbil species. Mongolian gerbils demonstrated tonic extension immediately after or within 1 min after the appearance of clonic convulsion. Very high amplitude spike waves appeared in these regions concurrent with the appearance of clonic convulsion. When the tonic extension appeared immediately after the clonic convulsion, the high amplitude spike waves continued during tonic convulsion. When the tonic extension occurred, high amplitude spike waves appeared in these three regions within a very short time, and afterward Mongolian gerbils died. Administration of valproic acid-Na (200 mg/kg), ethosuximide (100 and 200 mg/kg), clonazepam (2 mg/kg) and diazepam (0.5, 1 and 2 mg/kg) significantly prolonged the latency of clonic convulsion. Zonisamide-Na, phenytoin and carbamazepine, however, had no such effect. In Mongolian gerbils, tonic extension was demonstrated immediately after the appearance of clonic convulsion, yet, this effect was inhibited by all these drugs in a dose-dependent manner. Diazepam completely blocked the appearance of any behavioral changes in animals. These findings suggest that diazepam has a significant effect on flurothyl-induced seizures. Flurothyl-induced convulsions are associated with GABA receptors; hence, benzodiazepine (BDP) suppression may result from the strong relation between BDP and GABAnergic neurons.

Animals↗

DOPA cyclohexyl ester potently inhibits aglycemia-induced release of glutamate in rat striatal slices.

Brain ischemic insult causes glutamate release and resultant neuronal cell death. We here show that L-3,4-dihydroxyphenylalanine (DOPA) is a positive regulatory factor for glutamate release elicited by a mild brain insult using in vitro superfused rat striatal slices as a model system. Glucose deprivation for 18 min elicited release of glutamate, DOPA and dopamine (DA). Either tetrodotoxin (TTX) (1 microM) or alpha-methyl-p-tyrosine (alpha-MPT) (1 mM), a tyrosine hydroxylase inhibitor reduced markedly each of these releases. NSD-1015 (20 microM), an aromatic L-amino acid decarboxylase inhibitor restored the inhibition by alpha-MPT of glutamate and DOPA but not DA release. DOPA cyclohexyl ester (DOPA CHE) (0.3-1 microM), a competitive DOPA antagonist, concentration-dependently suppressed aglycemia-induced glutamate release, the effect which was mimicked neither by S-sulpiride nor SCH23390, a DA D(1) or D(2) receptor antagonist, respectively. Zonisamide (1-1000 microM), an anticonvulsant or YM872 (1 microM), an alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) a receptor antagonist produced no effect on aglycemia-induced glutamate release. DOPA CHE thus showed a relatively potent inhibitory action on aglycemia-induced glutamate release among several neuroprotective agents tested.

Animals↗

Differential catalytic properties in metabolism of endogenous and exogenous substrates among CYP3A enzymes expressed in COS-7 cells.

The catalytic properties of CYP3A7 in the metabolism of endogenous and exogenous substrates were compared with those of CYP3A4 and CYP3A5 using COS-7 expressing enzymes. The highest activities of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone 3-sulfate (DHEA-S) 16alpha-hydroxylase were observed in COS-7 cells expressing CYP3A7. In contrast, the activity of testosterone 6beta-hydroxylase of CYP3A7 expressed in COS-7 cells was much less than that of CYP3A4 expressed in COS-7 cells. The rate of carbamazepine 10, 11-epoxidation was the greatest in COS-7 cells expressing CYP3A4, followed by CYP3A5 and CYP3A7. On the other hand, the formation of reductive metabolite of zonisamide was the highest in COS-7 cells expressing CYP3A4, followed by CYP3A7 and CYP3A5. Furthermore, the addition of triazolam resulted in a decrease in 6beta-hydroxylation catalyzed by CYP3A7, but not by CYP3A4, whereas the pretreatment of microsomes with triacetyloleandomycin (TAO) resulted in a decrease in the reaction catalyzed by CYP3A4, but not by CYP3A7. Together with these results, it was suggested that CYP3A7 exerts differential catalytic properties not only in metabolism of endogenous substrates but also in drug metabolism compared to CYP3A4 and CYP3A5.

Adult↗

A case of epileptic negative myoclonus: therapeutic considerations.

This study presents a patient with epileptic negative myoclonus who showed interictal focal epileptic discharges in the centrotemporal region. The patient's seizures were exacerbated by carbamazepine, zonisamide, and valproate, but completely controlled by ethosuximide, and were suggested to have some relation with thalamocortical oscillation mechanisms. Ethosuximide is supposed to be a drug of worth to try to use in epileptic negative myoclonus patients with centrotemporal spike foci.

Anticonvulsants↗

Infantile spasms.

Infantile spasms constitute both a distinctive seizure type and an age-specific epilepsy syndrome that have been extensively described for over a century. Standardization of the classification of infantile spasms has evolved, culminating in recent recommendations for separately recognizing and distinguishing the seizure type (spasms or epileptic spasms) and the epilepsy syndrome of infantile spasms (West syndrome). More-detailed descriptions of the clinical and electrographic features of epileptic spasms and hypsarrhythmia have emerged. Advances in neuroimaging techniques have revealed clues about pathophysiology and increased the etiologic yield of the diagnostic evaluation of patients with infantile spasms. Adrenocorticotrophic hormone remains the treatment of choice for many neurologists. Recent controlled studies support vigabatrin as first-line therapy, and open-label studies suggest that topiramate, lamotrigine, and zonisamide may be useful in treating spasms. Recent reports of visual-field constriction with vigabatrin may limit its use. Surgical treatment has been used successfully in a select subgroup of patients with secondarily generalized spasms from a single epileptogenic zone. Although the prognosis for most patients with infantile spasms remains poor, further studies identifying predictors of favorable prognosis and recent advances in understanding the pathophysiology of infantile spasms offer hope of safer and more-effective therapies that improve long-term outcome.

Adrenocorticotropic Hormone↗

Oral high-dose phenobarbital therapy for early infantile epileptic encephalopathy.

We report oral high-dose phenobarbital therapy for a patient with early infantile epileptic encephalopathy with suppression bursts (Ohtahara syndrome). At 1 month of age, many series of tonic spasms, with raising limbs and crying lasting for a few minutes, developed and increased up to approximately 300 times per day. Initially intravenous midazolam (0.5 mg/kg/hour) slightly decreased the seizures, although oral vitamin B6, valproic acid, clonazepam, and zonisamide had little effect. Oral high-dose phenobarbital therapy was begun at a dosage of 15 mg/kg/day, and the seizures markedly decreased to 5-10 times per day and the epileptic discharges on electroencephalogram greatly decreased. Serum phenobarbital levels ranged between 60 and 100 mg/dL. High-dose phenobarbital therapy should be considered for the treatment of early infantile epileptic encephalopathy with suppression bursts.

Administration, Oral↗

A case of alternating hemiplegia of childhood with cerebellar atrophy.

A case of alternating hemiplegia of childhood is reported. Tonic fits and generalized tonic-clonic seizures developed during her infancy. Frequent twitching and apneic seizures appeared at 16 years of age. Zonisamide transiently suppressed the tonic, twitching and apneic seizures, as well as the facial and neck dystonia. Cranial computed tomography and magnetic resonance imaging revealed progressive vermian atrophy. Cerebellar dysfunction may play a role in the clinical features of some patients with alternating hemiplegia of childhood.

Adolescent↗

Cognitive deterioration associated with focal cortical dysplasia.

Surgery for an area of focal cortical dysplasia in a critical region is reported in a right-handed female manifesting intractable focal epilepsy and verbal cognitive deterioration. She developed the first seizure at 2 years of age and was treated with phenytoin and zonisamide, with good control until 10 years of age. Although seizures did not occur at 9 years of age, she manifested dyscalculia, right-left disorientation, and finger agnosia, and N-isopropyl-p-iodoamphetamine single-photon emission computed tomography (SPECT) revealed focal hypoperfusion in the left parietal lobe. At 11 years of age, she developed regular nocturnal seizures and gradually lost the ability to understand the meaning of sentences. Verbal IQ declined from 94 to 63, and the area of hypoperfusion detected by interictal N-isopropyl-p-iodoamphetamine SPECT spread over the left parietotemporal lobes. Magnetic resonance imaging revealed focal cortical dysplasia mainly in the left parietal lobe, and ictal technetium-99m-ethyl cysteinate dimer SPECT images demonstrated an area of hyperperfusion around the focal cortical dysplasia, including the left precentral gyrus. Because of the overlap between the epileptogenic and functional cortex, the authors concluded that cortical resection, including focal cortical dysplasia, was inappropriate in this patient.

Cerebral Cortex↗

Progress report on new antiepileptic drugs: a summary of the Fifth Eilat Conference (EILAT V).

The Fifth Eilat Conference on New Antiepileptic Drugs (AEDs) took place at the Dan Hotel, Eilat, Israel, 25-29 June 2000. Basic scientists, clinical pharmacologists and neurologists from 20 countries attended the conference, whose main themes included recognition of unexpected adverse effects, new indications of AEDs, and patient-tailored AED therapy. According to tradition, the central part of the conference was devoted to a review of AEDs in development, as well to updates on AEDs that have been marketed in recent years. This article summarizes the information presented on drugs in preclinical and clinical development, including AWD 131-138, DP-valproate, harkoseride, LY300164, NPS 1776, NW 1015, pregabalin, remacemide, retigabine, rufinamide and valrocemide. The potential value of an innovative strategy, porcine embryonic GABAergic cell transplants, is also discussed. Finally, updates on felbamate, fosphenytoin, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin, zonisamide, and the antiepileptic vagal stimulator device are presented.

Animals↗

Progress report on new antiepileptic drugs: a summary of the Sixth Eilat Conference (EILAT VI).

The Sixth Eilat Conference on New Antiepileptic Drugs (AEDs) took place in Taormina, Sicily, Italy from 7th to 11th April, 2002. Basic scientists, clinical pharmacologists and neurologists from 27 countries attended the conference, whose main themes included dose-response relationships with conventional and recent AEDs, teratogenic effects of conventional and recent AEDs, update on clinical implications of AED metabolism, prevention of epileptogesis, and seizure aggravation by AEDs. According to tradition, the central part of the conference was devoted to a review of AEDs in development, as well to updates on AEDs, which have been marketed in recent years. This article summarizes the information presented on drugs in preclinical and clinical development, including carabersat (SB-204269), CGX-1007 (Conantokin-G), pregabalin, retigabine (D-23129), safinamide, SPD421 (DP-VPA), SPM 927, talampanel and valrocemide (TV 1901). Updates on fosphenytoin, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin, zonisamide, new formulations of valproic acid, and the antiepileptic vagal stimulator device are also presented.

Animals↗

Myoclonus and epilepsy in childhood: 1996 Royaumont meeting.

Sudden and brief involuntary movements of central nervous system (CNS) origin called myoclonus may be cortical (motor strip), thalamocortical (thalamocortical loop) or reticular (caudal reticular formation). Epileptic, cortical and thalamocortical myoclonus are combined with a spike which, when it is focal, needs back-averaging to be demonstrated. Negative myoclonus due to lapse of tone can only be demonstrated during antigravidic posture and may be combined with either a slow wave or the second, positive component of a polyspike-wave. Epileptic myoclonus must be distinguished from epileptic spasms and tonic seizures, and from non-epileptic myoclonus, tics, tremor and chorea. Myoclonus may occur in partial symptomatic (mainly Rasmussen and dysplasia), cryptogenic (frontal) or idiopathic (negative myoclonus in CSWS) epilepsy. Generalized myoclonus is part of inborn errors of metabolism, non-progressive encephalopathy (mainly Angelman) and idiopathic epilepsy (juvenile and infantile benign and severe forms, and myoclonic-astatic epilepsy). Carbamazepine, vigabatrin and eventually lamotrigine may worsen myoclonus whereas it may be improved by benzodiazepines, valproate, lamotrigine, zonisamide and piracetam according to etiology. Pathophysiology must take in account maturation processes, lesions and genetic predisposition. However, precise mechanisms remain unknown and only hypotheses can be proposed, that could clarify the age-related EEG and clinical expression of the various syndromes.

Anticonvulsants↗