Efficacy and adverse effects of established and new antiepileptic drugs

The Extracellular Vesicle Citrullinome and Signature in a Piglet Model of Neonatal Seizures

Neonatal seizures are commonly associated with acute perinatal brain injury, while understanding regarding the downstream molecular pathways related to seizures remains unclear. Furthermore, effective treatment and reliable biomarkers are still lacking. Post-translational modifications can contribute to changes in protein function, and post-translational citrullination, which is caused by modification of arginine to citrulline via the calcium-mediated activation of the peptidylarginine deiminase (PAD) enzyme family, is being increasingly linked to neurological injury. Extracellular vesicles (EVs) are lipid-bilayer structures released from cells; they can be isolated from most body fluids and act as potential liquid biomarkers for disease conditions and response to treatment. As EVs carry a range of genetic and protein cargo that can be characteristic of pathological processes, the current study assessed modified citrullinated protein cargo in EVs isolated from plasma and CSF in a piglet neonatal seizure model, also following phenobarbitone treatment. Our findings provide novel insights into roles for PAD-mediated changes on EV signatures in neonatal seizures and highlight the potential of plasma- and CSF-EVs to monitor responses to treatment.

Attenuation of pharmaceutically active compounds in aqueous solution by UV/CaO2 process: Influencing factors, degradation mechanism and pathways

As freshwater sources continue to be influenced by wastewater effluents, there is a dire need to develop advanced water treatment processes capable of treating the wastewater-derived contaminants, especially for pharmaceutically active compounds (PhACs). Ultraviolet light (UV) combined with calcium peroxide (CaO₂) as an advanced oxidation process (AOP) to attenuate five widespread PhACs (carbamazepine (CBZ), primidone (PMD), phenobarbital (PBB), thiamphenicol (TAP) and florfenicol (FF)) was investigated in this paper. The degradation of these compounds followed pseudo-first-order kinetics (R² > 0.96). The optimum CaO₂ dosage was 0.1 g L^-1 and lower initial contaminants concentration was beneficial to their degradation. The UV/CaO₂ treatment of test PhACs was attributed to the combination of UV/H₂O₂ and UV-base-photolysis (UV/Ca(OH)₂), and the degradation mechanism was recognized as both UV direct photolysis and indirect photolysis caused by reactive radicals (•OH, triplet states of dissolved organic matter (³DOM*), and ¹O₂). Furthermore, the tentative transformation pathways of the five PhACs were proposed based on the detected intermediates and the degradation mechanisms. The final products of inorganic carbon and nitrogen indicate UV/CaO₂ treatment can significantly mineralize test PhACs. Also, the CaO₂ addition significantly reduced the energy consumption of UV irradiation according to electrical energy per order. The effective removal of CBZ and PMD in a secondary wastewater effluent by UV/CaO₂ treatment demonstrates the potential use of this AOP technology in advanced treatment of wastewater-derived PhACs.

Acute Ataxia in Children: A Review of the Differential Diagnosis and Evaluation in the Emergency Department

Acute ataxia in a pediatric patient poses a diagnostic dilemma for any physician. While the most common etiologies are benign, occasional individuals require urgent intervention. Children with stroke, toxic ingestion, infection, and neuro-inflammatory disorders frequently exhibit ataxia as an essential-if not the only-presenting feature. The available retrospective research utilize inconsistent definitions of acute ataxia, precluding the ability to pool data from these studies. No prospective data exist that report on patients presenting to the emergency department with ataxia. This review examines the reported causes of ataxia and attempts to group them into distinct categories: post-infectious and inflammatory central and peripheral phenomena, toxic ingestion, neurovascular, infectious and miscellaneous. From there, we synthesize the existing literature to understand which aspects of the history, physical exam, and ancillary testing might aid in narrowing the differential diagnosis. MRI is superior to CT in detecting inflammatory or vascular insults in the posterior fossa, though CT may be necessary in emergent situations. Lumbar puncture may be deferred until after admission in most instances, with suspicion for meningitis being the major exception. There is insufficient evidence to guide laboratory evaluation of serum, testing should be ordered based on clinical judgement-recommended studies include metabolic profiles and screening labs for metabolic disorders (lactate and ammonia). All patients should be reflexively screened for toxic ingestions.

Quantitative structure-activity relationship and molecular docking studies of a series of quinazolinonyl analogues as inhibitors of gamma amino butyric acid aminotransferase

Quantitative structure-activity relationship and molecular docking studies were carried out on a series of quinazolinonyl analogues as anticonvulsant inhibitors. Density Functional Theory (DFT) quantum chemical calculation method was used to find the optimized geometry of the anticonvulsants inhibitors. Four types of molecular descriptors were used to derive a quantitative relation between anticonvulsant activity and structural properties. The relevant molecular descriptors were selected by Genetic Function Algorithm (GFA). The best model was validated and found to be statistically significant with squared correlation coefficient (R²) of 0.934, adjusted squared correlation coefficient (R²_adj) value of 0.912, Leave one out (LOO) cross validation coefficient (Q²) value of 0.8695 and the external validation (R²_pred) of 0.72. Docking analysis revealed that the best compound with the docking scores of −9.5 kcal/mol formed hydrophobic interaction and H-bonding with amino acid residues of gamma aminobutyric acid aminotransferase (GABA_AT). This research has shown that the binding affinity generated was found to be better than the commercially sold anti-epilepsy drug, vigabatrin. Also, it was found to be better than the one reported by other researcher. Our QSAR model and molecular docking results corroborate with each other and propose the directions for the design of new inhibitors with better activity against GABA_AT. The present study will help in rational drug design and synthesis of new selective GABA_AT inhibitors with predetermined affinity and activity and provides valuable information for the understanding of interactions between GABA_AT and the anticonvulsants inhibitors.

Outcome Evaluation of Gabapentin as Add-on Therapy for Partial Seizures

Objective:

The safety, tolerability, efficacy, and impact on quality of life of gabapentin (Neurontin®) as adjunctive therapy to carbamazepine (CBZ) and/or phenytoin (PHT) was assessed in epileptic patients with partial seizures.

Methods:

NEON (Neurontin Evaluation of Outcomes in Neurological Practice) was an open-label, prospective, multicentre study conducted in patients on a stable dose of CBZ and/or PHT and experiencing an average of up to 4 complex partial seizures with or without secondary generalization per month, with no seizure-free months. The treatment lasted 20 weeks. Gabapentin was started at 400 mg/day and was individually titrated to effective tolerable dose up to 2400 mg/day. Quality of life was evaluated using the QOLIE-10 questionnaire.

Results:

A total of 141 patients were enrolled at 36 sites; 114 patients were evaluable for efficacy analyses. The mean maintenance dose of gabapentin was 1600 mg/day (range = 300-3200). A decrease of 50% or more in frequency of complex partial + secondarily generalized seizures was observed in 81 (71 %) patients (p = 0.0001). Fifty two (46%) patients were seizure-free during the last 8 weeks of treatment. A significant improvement (p < 0.05) was observed in 5 of the 10 questions of the QOLIE-10, as well as in the composite QOL score (p = 0.0002). The most frequent adverse events included somnolence (16%), dizziness (9%), and asthenia (6%). Twenty-five (18%) patients prematurely discontinued the study, 16 (11%) of them due to adverse events.

Conclusion:

This study indicates that treatment with gabapentin as adjunctive therapy to standard antiepileptic drugs in this group of patients not only provides significant improvement in seizure control, but also has a positive impact on quality of life. The clinical benefits in efficacy, safety and tolerability demonstrated at 20 weeks are sustained, and no tolerance develops with gabapentin in longer term use.

UV-photoconversion of ethosuximide from a longevity-promoting compound to a potent toxin

The anticonvulsant ethosuximide has been previously shown to increase life span and promote healthspan in the nematode Caenorhabditis elegans at millimolar concentrations. Here we report that following exposure to ultraviolet irradiation at 254 nm, ethosuximide is converted into a compound that displays toxicity toward C. elegans. This effect is specific for ethosuximide, as the structurally related compounds trimethadione and succinimide do not show similar toxicities following UV exposure. Killing by UV-irradiated ethosuximide is not attenuated in chemosensory mutants that are resistant to toxicity associated with high doses of non-irradiated ethosuximide. Non-irradiated ethosuximide extends life span at 15°C or 20°C, but not at 25°C, while irradiated ethosuximide shows similar toxicity at all three temperatures. Dietary restriction by bacterial deprivation does not protect against toxicity from irradiated ethosuximide, while non-irradiated ethosuximide further extends the long life spans of restricted animals. These data support the model that ethosuximide extends life span by a mechanism that is, at least partially, distinct from dietary restriction by bacterial deprivation and demonstrates an unexpected photochemical conversion of ethosuximide into a toxic compound by UV light.

Synthetic methods, chemistry, and the anticonvulsant activity of thiadiazoles

The chemistry of heterocyclic compounds has been an interesting field of study for a long time. Heterocyclic nucleus 1,3,4-thiadiazole constitutes an important class of compounds for new drug development. The synthesis of novel thiadiazole derivatives and investigation of their chemical and biological behavior have gained more importance in recent decades. The search for antiepileptic compounds with more selective activity and lower toxicity continues to be an active area of intensive investigation in medicinal chemistry. During the recent years, there has been intense investigation of different classes of thiadiazole compounds, many of which possess extensive pharmacological activities, namely, antimicrobial activity, anticonvulsant, antifungal antidiabetic, anti-inflammatory, antioxidant, and antituberculosis activities, and so forth. The resistance towards available drugs is rapidly becoming a major worldwide problem. The need to design new compounds to deal with this resistance has become one of the most important areas of research today. Thiadiazole is a versatile moiety that exhibits a wide variety of biological activities. Thiadiazole moiety acts as "hydrogen binding domain" and "two-electron donor system." It also acts as a constrained pharmacophore. On the basis of the reported literature, we study here thiadiazole compounds and their synthetic methods chemistry and anticonvulsant activity.

Comparative Molecular Similarity Indices Analysis of 1-(Naphthylalky1)-1H-imidazole Analogs with Antiepileptic Activity

A three-dimensional quantitative structure-activity relationship (3D QSAR) of 44 structurally and functionally diverse series of 1- (Naphthylalkylimidazoles) as antiepileptic agents was studied using the Comparative molecular similarity indices analysis (CoMSIA) method. A training set containing 34 molecules served to establish the models. The optimum CoMSIA model obtained for the training set were all statistically significant, with cross-validated coefficients (q(2)) of 0.725 and conventional coefficients (r(2) (ncv)) of 0.998. The predictive capacities of the model were successfully validated by using a test set of 10 molecules that were not included in the training set. CoMSIA model (Model 1) obtained from the hydrophobic and Hbond acceptor field was found to have the best predictivity, with a predictive correlation coefficient (r(2) (pred)) of 0.67. The information obtained from this 3D-QSAR model can be used to guide the development of imidazoles as novel antiepileptic agents.

Ethosuximide: from bench to bedside

Ethosuximide, 2-ethyl-2-methylsuccinimide, has been used extensively for "petit mal" seizures and it is a valuable agent in studies of absence epilepsy. In the treatment of epilepsy, ethosuximide has a narrow therapeutic profile. It is the drug of choice in the monotherapy or combination therapy of children with generalized absence (petit mal) epilepsy. Commonly observed side effects of ethosuximide are dose dependent and involve the gastrointestinal tract and central nervous system. Ethosuximide has been associated with a wide variety of idiosyncratic reactions and with hematopoietic adverse effects. Typical absence seizures are generated as a result of complex interactions between the thalamus and the cerebral cortex. This thalamocortical circuitry is under the control of several specific inhibitory and excitatory systems arising from the forebrain and brainstem. Corticothalamic rhythms are believed to be involved in the generation of spike-and-wave discharges that are the characteristic electroencephalographic signs of absence seizures. The spontaneous pacemaker oscillatory activity of thalamocortical circuitry involves low threshold T-type Ca2+ currents in the thalamus, and ethosuximide is presumed to reduce these low threshold T-type Ca2+ currents in thalamic neurons. Ethosuximide also decreases the persistent Na+ and Ca2+ -activated K+ currents in thalamic and layer V cortical pyramidal neurons. In addition, there is evidence that in a genetic absence epilepsy rat model ethosuximide reduces cortical gamma-aminobutyric acid (GABA) levels. Also, elevated glutamate levels in the primary motor cortex of rats with absence epilepsy (but not in normal animals) are reduced by ethosuximide.

The adverse effects of antiepileptic drugs in children

Efficacy of antiepileptic drugs (AEDs) are often equivalent, hence selection of an AED is often determined by the adverse effects (AEs). The development of neurocognitive AEs is almost inevitable with use of AEDs, especially in high-risk groups. Teratogenesis with major or minor malformations is of great concern during the first trimester of pregnancy, but an increasing body of information suggests that potential neurocognitive developmental delay may also occur with use of AEDs in the latter part of pregnancy. Decreased bone mineral density has been found in adults and children receiving both enzyme-inducing AEDs and valproate, an enzyme-inhibiting drug. AEDs may influence the lipid profile, body weight, reproductive, hormonal and other endocrine functions, and sleep architecture. There are age-specific AEs related to pharmacokinetic differences that have been highlighted in this review with emphasis on the pediatric population. A classification of AEs using different parameters is also included.

Protective effect of safranal on pentylenetetrazol-induced seizures in the rat: involvement of GABAergic and opioids systems

The aim of the present study was to evaluate the effects of safranal, an active constituent of Crocus sativus L. stigmas, on seizures induced by pentylenetetrazol. Intracerebroventricular (i.c.v.) microinjection of safranal (4.84, 9.68 and 24.2 micromol) had no effects on tonic and clonic phases as well as mortality upon seizures induced by PTZ (90mg/kg body wt., i.p.). Peripheral administration of safranal (72.75, 145.5 and 291 mg/kg body wt., i.p.), however, induced a dose-dependent decrease in the incidence of both minimal clonic seizures (MCS) (145.5 mg/kg body wt., p<0.01) and generalized tonic-clonic seizures (GTCS) (145.5 mg/kg body wt., p<0.001) following PTZ administration. Safranal also increased MCS and GTCS latency, significantly. Percent of protection against GTCS was 30%, 100% and 100% and mortality protection percent was 40%, 100% and 100% for the mentioned doses, respectively. Pretreatment with flumazenil (5 nmol, i.c.v.) and naloxone (5.5 nmol, i.c.v. and 2 mg/kg body wt., i.p.), 15 min prior to safranal administration (145.5 mg/kg body wt., i.p.), abolished the protective effect of safranal on MCS. Flumazenil also decreased the effect of safranal on incidence as well as latency of GTCS, significantly. These effects were not, however, significant for naloxone (5.5 nmol, i.c.v. and 2mg/kg body wt., i.p.). Results of this study demonstrated that safranal could exert anticonvulsant activity in the PTZ model and this effect may be mediated, at least partly, through GABA(A)-benzodiazepine receptor complex.

The Liverpool Adverse Events Profile: relation to AED use and mood

PURPOSE

The Liverpool Adverse Events Profile (LAEP) is used as a systematic measure of adverse effects from antiepileptic drugs (AEDs). This study evaluated LAEP in newly diagnosed seizure patients, and examined the relation between LAEP, anxiety, and depression.

METHODS

Seizure patients seen in the two First Seizure Clinics were categorized into group A (AEDs commenced after assessment), group B (AEDs commenced before assessment), and group C (no AEDs). LAEP and the Hospital Anxiety and Depression Scale (HADS) were completed at baseline (n=164) and 3 months (n=103). Each LAEP symptom was assessed for baseline frequency, 3-month frequency, and frequency change over a 3-month period. Global scores for LAEP and HADS were analysed at baseline and 3 months.

RESULTS

Symptom-reporting patterns were similar between groups. However, increased frequency over a 3-month period occurred for 12 symptoms in group A, 10 in group B, and one in group C. Global LAEP and HADS showed no significant group differences at baseline or changes over a 3-month period. Multiple regression revealed that HADS scores predicted LAEP global scores better than did AED status. Multivariate analyses of variance demonstrated that increased reporting of 16 of 19 LAEP symptoms was significantly related to higher anxiety and depression rates.

CONCLUSIONS

In a First Seizure Clinic, LAEP detects changes in specific symptom frequencies when used as a repeated, symptom-by-symptom measure. Increased symptom frequency is associated with diagnostic category/AED treatment, anxiety, and depression. Global LAEP scores do not illustrate differences in symptom reporting between patients.

Pharmacovigilance in epileptic patients using antiepileptic drugs

OBJECTIVE

To investigate the occurrence of adverse effects of antiepileptic drugs (AED) in chronic epileptic patients in mono or polytherapy.

METHOD

We evaluated consecutive patients that met the following inclusion criteria: age of 18 years or older, diagnosis of epilepsy for at least one year, stable dose of AED for at least three months. Patients were asked if they had any adverse event related to the AED. After that, they were interviewed according to a detailed semi-structure questionnaire. We also assessed specifically the adverse events in the last four weeks. The data were analyzed regarding the use of monotherapy x polytherapy, and the presence of probable depression (score>15) according to the Center for Epidemiologic Studies Depression Scale.

RESULTS

Sixty-five patients were evaluated, 35 women, mean age 38.3 years; 35 patients were in use of monotherapy and 35 in polytherapy. Only 45 (69.2%) patients spontaneously reported adverse effects. After the formal questionnaire, 63 (97%) patients referred experiencing an adverse event (p<0.001). Seventeen men had adverse events, as opposed to 28 women (p=0.042). When the last four weeks were evaluated, patients with probable depression presented adverse events more frequently (p<0.0001).

CONCLUSION

Our data suggest that adverse events are highly prevalent when a detailed questionnaire is applied and that depression may aggravate the number and intensity of side effects in patients using AEDs.

Azolylchromans as a novel scaffold for anticonvulsant activity

A series of azolylchroman derivatives were prepared as conformationally constrained analogs of (arylalkyl)azole anticonvulsants. The anticonvulsant activities of the compounds were evaluated by determining seizure latency and protective effect against pentylenetetrazole (PTZ)-induced lethal convulsions in mice at a dose of 5mg/kg. Among these compounds, 7-chloro-3-(1H-imidazol-1-yl)chroman-4-one and 3-(1H-1,2,4-triazol-1-yl)chroman-4-one exhibited significant action in delaying seizures as well as effective protection against PTZ-induced seizures and deaths.

Tiagabine as add-on therapy may be more effective with valproic acid--open label, multicentre study of patients with focal epilepsy

The aim of the current study was to review the efficacy of tiagabine (TGB) as add-on therapy in patients with drug-resistant focal epilepsy under normal daily clinical practice, and try to identify those who had improvement. This was an open multicentre study conducted in Poland. A group of 330 patients were analysed. Patients received TGB up to 30-50 mg/day with adjustment within the therapeutic range and titration period. For statistical evaluation chi-square test and logistic analysis were used. At the 16-week follow-up visit, 71.4% patients were reported as responders, i.e. had a 50% or greater decrease in seizure frequency compared with baseline (P<0.001). One-third of patients were seizure-free at 16-week evaluation (P<0.001). The beneficial effect of TGB on seizure reduction was most marked in patients with partial seizures (P<0.001). Patients who used valproic acid (mean dose 1307 mg/day) had 61-85% higher chances for disappearance of seizures or reduction of their number by 50% or more. Patients who used carbamazepine (mean dose 800 mg/day) at a dose 1000 mg or higher mg/day had twice lower chance for reduction of seizures by 50% or more (OR=0.45; 95 CI 0.25-0.82). There was no statistical impact of sex, age and aetiology on probability of therapeutic effect.

Effects of the combination of valproate and ethosuximide on spike wave discharges in WAG/Rij rats

OBJECTIVE

We studied the interaction between valproate (VPA) and ethosuximide (ESM) in diminishing the incidence of absence-like spike-wave discharges (SWDs) in the EEG of WAG/Rij rats.

METHODS

VPA, ESM, their combination and saline were evaluated in 16 rats. The doses of VPA ranged from 0 to 280 mg/kg and the doses of ESM ranged from 0 to 40 mg/kg. For the drug combination, a fixed weight ratio of 7/1 VPA/ESM was used. The incidence of SWDs in the EEG was determined for the period of 15-75 min after injection and compared to the incidence of SWDs prior to injection. The sigmoid-E(max) equation was fitted to the data. Isobolic analysis, on 50% effect, was used to assess the character of the drug interaction.

RESULTS

The parameters for diminishing the incidence of the SWDs were: VPA: ED(50): 121mg/kg; ESM: ED(50): 21.5mg/kg; VPA/ESM: ED(50): 112/16 mg/kg. Isobolic analysis showed that a higher drug load was needed of the combination than of the individual drugs to achieve a 50% reduction of SWDs: factor 1.67; P = 0.012.

CONCLUSION

The interaction between valproate and ethosuximide was shown to be infra-additive in diminishing the incidence of SWDs in WAG/Rij rats.

The specialist nurse role in the treatment of refractory epilepsy

The main aim of epilepsy treatment is rapid and complete control of seizures without antiepileptic drug (AED) side effects. This outcome is achieved in 60-70% of newly diagnosed patients. In refractory epilepsy, new AEDs render some additional patients seizure free but make treatment more complex. The choice of AEDs, their differing pharmacokinetics, efficacy, tolerability and potential interactions are multiplied. Up to of 75% of patients develop AED side effects, most AEDs can cause paradoxical reactions, and when AED doses are changed seizures may worsen. Despite the increased complexity of epilepsy treatment and the biomedical and psychosocial consequences of uncontrolled seizures, many patients have difficulty accessing specialist services. A service that involves the epilepsy nurse specialist (ENS) giving patients and General Practitioners (GPs) free access to treatment advice has recently been established to improve care. Over a 2-week period 60 treatment-related telephone or outpatient consultations were provided out of a total of 124 contacts. Changes to the AED regimen were implemented in 44/60, and the GP was notified by letter in 31/44. The audit results are presented and epilepsy treatment including AED efficacy, tolerability, interactions and side effects are discussed.

Inhibition of sustained repetitive firing in cultured hippocampal neurons by an aqueous fraction isolated from Delphinium denudatum

In this report we investigated the effects of the aqueous fraction (AF) isolated from Delphinium denudatum on sustained repetitive firing in cultured neonatal rat hippocampal pyramidal neurons. Blockade of SRF is one of the basic mechanisms of antiepileptic drugs (AED) at the cellular level. The effects of aqueous fraction (0.2-0.6 mg/ml) were compared with the prototype antiepileptic drug, phenytoin (PHT). Using the whole cell current-clamp technique, sustained repetitive firing was elicited in neurons by a depolarizing pulse of 500 ms duration, 0.3 Hz and 0.1-0.6 nA current strength. Similar to phenytoin, aqueous fraction reduced the number of action potentials (AP) per pulse in a concentration-dependent manner until no action potentials were elicited for the remainder of the pulse. There was a corresponding use-dependent reduction in amplitude and Vmax (velocity of upstroke) of action potentials. The Vmax and amplitude of the first action potential was not affected by phenytoin, while aqueous fraction exhibited concentration-dependent reduction. At 0.6 mg/ml aqueous fraction reduced Vmax to 58-63% and amplitude to 16-20% of the control values. The blockade of sustained repetitive firing by aqueous fraction was reversed with hyperpolarization of membrane potential (-65 to -75 mV) while depolarization of membrane potential (-53 to -48 mV) potentiated the block. The results suggest that aqueous fraction blocks sustained repetitive firing in hippocampal neurons in a use-dependent and voltage-dependent manner similar to phenytoin. However, unlike phenytoin, which interacts preferably with the inactive state of the Na+ channel, the compounds present in aqueous fraction apparently also interact with the resting state of the Na+ channels as suggested by dose-dependent reduction of Vmax and amplitude of first AP. We conclude that aqueous fraction contains potent anticonvulsant compounds.

Effects Of Generic-Only Drug Coverage In A Medicare HMO

Rising pharmacy costs and demand for prescription drug coverage for broader populations of seniors have resulted in the implementation of generic-only pharmacy benefits in Medicare health maintenance organizations (HMOs). The impact on cost and quality of care is unknown. We examined data for members of a California Medicare HMO whose coverage changed to a generic-only benefit and found that the change was associated with reduced health plan pharmacy cost, increased out-of-pocket pharmacy costs for members, increased overall hospital admissions, changed drug-use patterns, and a negative impact on quality metrics for certain conditions. These findings have important implications for future research and health policy decisions.

Acute management of seizures in the syndromes of idiopathic generalized epilepsies

Three of the seizure types (myoclonic, absence, and generalized tonic-clonic) and syndromes associated with idiopathic generalized or genetic epilepsies can present an acute status epilepticus picture that requires acute therapy. These are not the usual seizures observed in status epilepticus because most of these patients have secondary generalized or symptomatic generalized convulsive seizures. In this review, I discuss the unique presentation and treatment options for the acute management of seizures in the syndromes of idiopathic generalized epilepsy (IGE), with special emphasis on the seizures of status epilepticus, which persist over time or occur in a series without recovery of consciousness.

Tender points as predictors of distress and the pharmacologic management of fibromyalgia syndrome

The object of this study was to determine the association between tender point pain ratings, tender point counts and distress in people with fibromyalgia and to review the pharmacotherapy of fibromyalgia. Demographic, psychosocial, and health status information was collected from 316 health maintenance organization members with fibromyalgia. A manual tender point exam was conducted. Tender point counts predicted 3.0%, and tender point severity ratings predicted 8.3%, of the variance in distress. Little difference was found between the variance predicted for physical versus psychologic distress. A principal components analysis of all measures produced four distinct factors: global-physical functioning, tender points, psychologic, and physical. Tender point pain ratings and counts predicted a small but significant amount of variance in distress. In addition, FMS involves at least four rather distinct factors, one of which is related to tender points. Pharmacotherapeutic management is provided on a patient-specific basis including pharmacokinetics, pharmacodynamic, pathophysiologic, and psychosocial needs designed and modulated for each individual patient.

Volume-selective 1H MR spectroscopy for in vivo detection of valproate in patients with epilepsy

We performed volume-selective 1H MR spectroscopy (1H-MRS) on 12 patients on valproate monotherapy to detect valproate in vivo in the brain. We also acquired reference valproate spectra in vitro in subphysiological 15 g/l albumin solution in saline, in which valproate showed two resonance peaks at 0.7 and 1.2 ppm and a minimum detection threshold of 240 mg/l. In vivo 1H-MRS spectra in brain showed peaks between 0.6 and 1.6 ppm. Simultaneous serum valproate concentrations did not correlate with these integrated MRS peaks. On follow-up, changes in these signals also did not correlate with increasing serum valproate levels. The inconsistency of in vivo 1H-MRS signals at varying serum levels and the high detection levels in vitro suggest that valproate signals are missed in vivo because valproate is metabolised or strongly bound, presumably to brain macromolecules.

Correlation between anticonvulsant activity and inhibitory action on glial gamma-aminobutyric acid uptake of the highly selective mouse gamma-aminobutyric acid transporter 1 inhibitor 3-hydroxy-4-amino-4,5,6,7-tetrahydro-1,2-benzisoxazole and its N-alkylated analogs

The inhibitory effect of 3-hydroxy-4-amino-4,5,6,7-tetrahydro-1,2-benzisoxazole (exo-THPO) and its N-methylated (N-methyl-exo-THPO) and N-ethylated (N-ethyl-exo-THPO) analogs, derived from gamma-aminobutyric acid (GABA) and 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridin-3-ol (THPO) on GABA transport was investigated using cultured neocortical neurons (GABA-ergic) and astrocytes and cloned mouse GABA transporters GAT1-4 expressed in human embryonic kidney (HEK) 293 cells. Anticonvulsant activity was assessed after i.c.v. administration to Frings audiogenic seizure-susceptible mice. Anticonvulsant activity of the O-pivaloyloxymethyl prodrug of N-methyl-exo-THPO was assessed after i.p. administration. Results from these studies were compared with those obtained from similar studies with the novel anticonvulsant drug tiagabine, which acts via inhibition of GABA transport. exo-THPO and its N-alkyl analogs inhibited neuronal, astrocytic, and GAT1-mediated GABA transport but not GABA uptake mediated by GAT2-4. N-Methyl-exo-THPO was 8-fold more potent as an inhibitor of astrocytic versus neuronal GABA uptake. The IC(50) value for inhibition of GABA uptake by GAT1 closely reflected its IC(50) value for inhibition of neuronal uptake. Tiagabine was approximately 1000-fold more potent than exo-THPO and its alkyl derivatives as an inhibitor of GABA uptake in cultured neural cells and GAT1-expressing HEK 293 cells. exo-THPO, its alkylated analogs, and tiagabine displayed a time- and dose-dependent inhibition of audiogenic seizures after i.c.v. administration. N-Methyl-exo-THPO was the most potent anticonvulsant among the exo-THPO compounds tested and only slightly less potent than tiagabine. The findings suggest a correlation between anticonvulsant efficacy and selective inhibition of astroglial GABA uptake. Furthermore, results obtained with the N-methyl-exo-THPO prodrug demonstrate the feasibility of developing a glial-selective GABA uptake inhibitor with systemic bioavailability.

Antagonists of GLU(K5)-containing kainate receptors prevent pilocarpine-induced limbic seizures

Developments in the molecular biology and pharmacology of GLU(K5), a subtype of the kainate class of ionotropic glutamate receptors, have enabled insights into the roles of this subunit in synaptic transmission and plasticity. However, little is known about the possible functions of GLU(K5)-containing kainate receptors in pathological conditions. We report here that, in hippocampal slices, selective antagonists of GLU(K5)-containing kainate receptors prevented development of epileptiform activity--evoked by the muscarinic agonist, pilocarpine--and inhibited the activity when it was pre-established. In conscious rats, these GLU(K5) antagonists prevented and interrupted limbic seizures induced by intra-hippocampal pilocarpine perfusion, and attenuated accompanying rises in extracellular L-glutamate and GABA. This anticonvulsant activity occurred without overt side effects. GLU(K5) antagonism also prevented epileptiform activity induced by electrical stimulation, both in vitro and in vivo. Therefore, we propose that subtype-selective GLU(K5) kainate receptor antagonists offer a potential new therapy for epilepsy.

Anticonvulsant activities of ethanolic extract and aqueous fraction isolated from Delphinium denudatum

Dried roots of Delphinium denudatum Wall. are a popular folk remedy for the treatment of epilepsy in the traditional Unani system of medicine in the sub-continent. We carried out anticonvulsant screening of the ethanolic extract (EE) and aqueous fraction (AF) of this plant utilising the maximal electroshock (MEST) and subcutaneous pentylenetetrazole (scPTZ), bicuculline (scBIC), picrotoxin (scPTX) and strychnine (scSTN) tests for anticonvulsant activity. EE had weak dose-dependent anticonvulsant effects on seizures induced by PTZ and BIC. AF exhibited dose-dependent activity against hind limb tonic extension phase (HLTE) of MEST and comparatively stronger anticonvulsant activity against seizures induced by PTZ and BIC. The results suggest the presence of potent anticonvulsant compounds in AF of D. denudatum and deserve further investigation for isolation of active compounds and elucidation of the mechanism of anticonvulsant action.

Life-threatening adverse events of antiepileptic drugs

Treating a patient with antiepileptic drugs (AEDs) may give rise to unexpected life-threatening adverse events. Despite extensive experimental and clinical testing to ensure safety, most AEDs on the market have been associated with cases of severe cutaneous reactions, serious hematological disorders, or hepatic failure. Most of these disorders emerge as idiosyncratic immune-mediated disease or are related to toxic metabolic products of the AEDs. Early diagnosis is the only means of reducing the harmful, potentially fatal effects of these reactions. A high degree of suspicion, knowledge of risk factors, and close physician-patient contact increases the likelihood of early diagnosis and treatment. When diagnosed, severe reactions must be fully documented and reported to health authorities. The very rare occurrence of life threatening events should not, in general, limit treatment decision-making. Future epidemiological, chemical, and genetic research might provide methods for ascertaining which patients are at risk, so undue exposure can be avoided.

Adjunctive agents in the management of chronic pain

Chronic pain syndromes include cancer-related pain, postherpetic neuralgia, painful diabetic neuropathy, and central poststroke pain and are common in the elderly. Adjunctive (or adjuvant) analgesics, defined as drugs that do not contain acetaminophen and those not classified as nonsteroidal antiinflammatory or opioid agents, play a role in the management of chronic pain. The term "adjunctive" (or "adjuvant") is a misnomer as several of these agents may constitute first-line therapy for many chronic pain syndromes. Tricyclic antidepressants have formed the backbone of therapy for chronic neuropathic pain for years. However, the difficulty with using agents of this class, due to their clinically significant adverse-event potential, has led to the evaluation of other agents, most notably, the antiepileptic drugs. The most useful are gabapentin, carbamazepine, and lamotrigine. In selected patients, baclofen, mexiletine, and clonidine may be useful as well. Cancer-related pain may respond substantially to corticosteroids, and pain associated with bone metastases to parenteral bisphosphonates and strontium. Practitioners should consider these alternative agents when treating chronic pain.

Anticonvulsant activities of the FS-1 subfraction isolated from roots of Delphinium denudatum

Delphinium denudatum Wall. (Ranunculaceae) is a medicinal herb used for the treatment of epilepsy in the subcontinent. The present study reports the anticonvulsant activities in the maximal electroshock test (MEST) and subcutaneous pentylenetetrazole (PTZ), bicuculline (BIC), picrotoxin (PIC)-induced seizures of the FS-1 subfraction (FS-1) that was obtained by purification of an aqueous fraction isolated from the roots of D. denudatum. In CF 1 mice, FS-1 (600 mg/kg i.p.) exhibited very potent anticonvulsant activity that was comparable to the effects of the well-known antiepileptic drug phenytoin (20 mg/kg) in MEST and protected 100% animals from hind limb tonic extension phase of this model. FS-1 also suppressed PTZ-induced threshold seizure and the loss of the righting reflex with tonic fore and hind limb extension by 100%, similar to the antiepileptic drug valproic acid (350 mg/kg). BIC-induced seizures were suppressed in 80% of the animals. FS-1 exhibited weak anticonvulsant effect on PIC-induced seizures, however, it significantly reduced mortality and delayed the onset of seizures. FS-1 had no effect on strychnine (STN)-induced extensor seizures. The results demonstrate the broad and potent anticonvulsant activity of the compounds in FS-1 of D. denudatum.

Topiramate in the catastrophic epilepsies of childhood

Several epileptic syndromes that occur during childhood are characterized by severe treatment-resistant seizures, progressive loss of higher intellectual functions, and characteristic electroencephalographic abnormalities. These catastrophic epileptic syndromes include epileptic encephalopathy with diffuse slow spike waves (Lennox-Gastaut syndrome), West syndrome, progressive myoclonic epilepsies, and electrical status epilepticus during sleep. This article summarizes each syndrome and reviews the most recent information concerning the effectiveness of topiramate with respect to each condition. Suggestions are offered to help clinicians maximize topiramate's efficacy and tolerability in patients suffering with these syndromes. Overall, topiramate is a valuable antiepileptic medication in the treatment of catastrophic pediatric epileptic syndromes.

Vagus nerve stimulation and the ketogenic diet

Antiepileptic drugs are the primary form of treatment for patients with epilepsy. In the United States, hundreds of thousands of people do not achieve seizure control, or have significant side effects, or both. Only a minority of patients with intractable epilepsy are candidates for traditional epilepsy surgery. Vagus nerve stimulation is now the second most common treatment for epilepsy in the United States. Additionally, the ketogenic diet has established itself as a valid treatment. This article discusses the history, mechanism of action, patient selection, efficacy, initiation, complications, and advantages of vagus nerve stimulation and the ketogenic diet.

Amlodipine enhances the activity of antiepileptic drugs against pentylenetetrazole-induced seizures

Amlodipine (AML), which belongs to the 1,4-dihydropyridine calcium channel antagonists, possesses pharmacological and pharmacokinetic profile that distinguishes it from other agents of this class. Pentylenetetrazole (PTZ)-induced clonic and tonic convulsions in mice were significantly reduced by administration of AML at 10 mg/kg. At this dose AML remained without influence upon the plasma level of PTZ. The ED50 value of AML against clonic seizures induced by PTZ was 5.4 mg/kg. This calcium channel antagonist (at 2.5 mg/kg) combined with ethosuximide (ETX), valproate magnesium (VPA) or phenobarbital (PB) significantly reduced their ED50 values against clonic phase of PTZ-induced seizures. AML administered alone or in combination with antiepileptic drugs (AEDs) worsened the motor performance of mice in the chimney test. However, these treatments remained without significant influence on the retention time in the passive avoidance test. Plasma levels of antiepileptics remained unchanged in the presence of AML. The results indicate that AML does not seem a good candidate for a combination therapy in epileptic patients because of its adverse potential.

Topiramate titration and tolerability

OBJECTIVE

To evaluate the tolerability and efficacy of two titration rates for topiramate initiated as adjunctive therapy in adults with partial-onset seizures, with or without secondary generalization, in a multicenter, double-blindtrial.

METHODS

After a two-week baseline phase, 188 patients were randomized to either a 50/50 titration schedule (initial dosage 50 mg/d increased in 50-mg/d increments at weekly intervals; n = 95) or to a 100/200 titration schedule (initial dosage 100 mg/d increased by 100-200 mg/d at weekly intervals; n = 93). The maximum dosage of 400 mg/d was therefore achieved in eight weeks or three weeks, respectively.

RESULTS

Compared with the 100/200 titration rate, the 50/50 titration rate significantly reduced the cumulative incidence of treatment-emergent adverse events (TEAEs) leading to changes in topiramate therapy (ie., dosage reductions, interruptions or discontinuations of therapy) (p = 0.048) and significantly reduced treatment interruptions or withdrawals due to TEAEs (p = 0.040). Mild or moderate effects involving the central nervous system were the most frequent adverse events. At the final visit, therapeutic responses were comparable in the 50/50 and 100/200 titration groups: median percent seizure reduction was 42% vs. 33%, proportion of patients with 250% seizure reduction was 42% vs. 38%, and proportion of patients with no seizures during double-blind treatment was 14% vs. 10%, respectively. Seizure frequency was substantially reduced from baseline during topiramate titration. At day 22, with the 50/50 titration group receiving 150 mg/d and the 100/200 titration group receiving 400 mg/d, the mean percent seizure reduction was 51% and 54%, respectively.

CONCLUSIONS

Gradual initiation of topiramate therapy can significantly enhance patient tolerability without delaying therapeutic response.

Antiepileptic teratogen valproic acid (VPA) modulates organisation and dynamics of the actin cytoskeleton

The antiepileptic drug valproic acid (VPA) and teratogenic VPA analogues have been demonstrated to inhibit cell motility and affect cell morphology. We here show that disruption of microtubules or of microfilaments by exposure to nocodazole or cytochalasin D had different effects on morphology of control cells and cells treated with VPA, indicating that VPA affected the cytoskeletal determinants of cell morphology. Furthermore, VPA treatment induced an increase of F-actin, and of FAK, paxillin, vinculin, and phosphotyrosine in focal adhesion complexes. These changes were accompanied by increased adhesion of VPA-treated cells to the extracellular matrix. Treatment with an RGD-containing peptide reducing integrin binding to components of the extracellular matrix partially reverted the motility inhibition induced by VPA, indicating that altered adhesion contributed to, but was not the sole reason for the VPA mediated inhibition of motility. In addition it is shown that the actomyosin cytoskeleton of VPA-treated cells was capable of contraction upon exposure to ATP, indicating that the reduced motility of VPA-treated cells was not caused by an inhibition of actomyosin contraction. On the other hand, VPA caused a redistribution of the actin severing protein gelsolin, and left the cells unable to respond to treatment with a gelsolin-peptide known to reduce the amount of gelsolin bound to phosphatidylinositol bisphosphate (PIP2), leaving a larger amount of the protein in a potential actin binding state. These findings indicate that VPA affects cell morphology and motility through interference with the dynamics of the actin cytoskeleton.

NMDA- but not kainate-mediated events reduce efficacy of some antiepileptic drugs against generalized tonic-clonic seizures in mice

PURPOSE

The aim of this study was to evaluate the efficacy of conventional antiepileptic drugs (AEDs) against the generalized tonic-clonic seizures in mice subjected to the subconvulsive doses of N-methyl-D-aspartate (NMDA) or kainate.

METHODS

Mice were given NMDA and kainate in the doses of 50.0 and 9.0 mg/kg i.p., respectively [i.e., equal to 75% of their CD16 values (convulsive dose in 16% of the animals studied)]. Subsequently the anticonvulsive potential of conventional AEDs against the maximal electroshock-induced seizures was estimated. Where necessary, the plasma levels of AEDs were assessed.

RESULTS

NMDA or kainate application did not affect the electroconvulsive threshold. NMDA, but not kainate, diminished the antiepileptic activity of diazepam (DZP) and carbamazepine (CBZ), increasing their 50% effective doses (ED50s) from 14.1 and 8.6 to 19.0 and 12.1 mg/kg i.p., respectively. Neither NMDA nor kainate affected the ED50 for valproate (VPA), phenobarbital (PB), or diphenylhydantoin (DPH) against electroconvulsions. NMDA-evoked effects were reversed with the use of the NMDA antagonist, D-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid (CGP 40116) and were not accompanied by the alterations in the free plasma levels of AEDs.

CONCLUSIONS

The NMDA-mediated events, but not kainate-related ones, seem to be involved in the protective action of DZP and CBZ against maximal electroshock-induced seizures. Moreover, it might be concluded that when subthreshold activation of NMDA receptors adds to other epileptogenic factors, DZP and CBZ are less efficacious. Presented data indicate that in such situations, adding the NMDA receptor antagonist (at very low doses) to the AED may yield beneficial therapeutic effects.

Magnetoencephalography in presurgical evaluation of children with the Landau-Kleffner syndrome

PURPOSE

Our aim was (a) to localize the primary epileptogenic cortex for possible multiple subpial transsection in four children with the Landau-Kleffner syndrome (LKS), and (b) to evaluate the impact of magnetoencephalography (MEG) in the localizing process.

METHODS

We used EEG to detect the overall epileptiform activity and MEG for selective recording of fissural spikes. The cortical generators of MEG spikes were modeled with dipoles, and their activation order was determined. The voltage distribution, consistent with the earliest MEG sources, was then identified during the course of the patient's EEG spikes to determine the relative timing between stereotypic EEG and MEG spikes and to distinguish the earliest (primary) source area among the secondary ones.

RESULTS

In all patients, the earliest spike activity originated in the intrasylvian cortex, spreading in one subject to the contralateral sylvian cortex within 20 ms. Secondary spikes occurred within 10-60 ms in ipsilateral perisylvian, temporooccipital, and parietooccipital areas. A single intrasylvian pacemaker initiated all epileptic activity in two patients, whereas the other two had independent left- and right-hemisphere circuits or focal spikes. MEG source dynamics predicted the results of the methohexital suppression test in two patients and was confirmed by surgery outcome in one patient, in whom all epileptic activity ceased after a small transsection of the sylvian pacemaker.

CONCLUSIONS

(a) The intrasylvian cortex is a likely pacemaker of epileptic discharges in LKS, and (b) MEG provides useful presurgical information of the cortical spike dynamics in LKS patients.

Use of topiramate, a new anti-epileptic as a mood stabilizer

RATIONALE

Because some anti-epileptic drugs (AEDs) are effective in bipolar affective disorders, the new AED topiramate (TPM) may be effective in psychiatric illnesses. TPM was evaluated in mood disorders refractory to previous therapies including newer AEDs.

METHODS

Charts of 58 consecutive patients, 39 outpatients (15 males, 24 females) and 19 inpatients (6 males, 13 females) were reviewed. TPM 25 mg. b.i.d. was added to existing therapy and titrated in 50 mg increments every 3-7 days. Improvement was rated on a Likert global assessment scale of marked, moderate, mild, or no improvement or worse, based on quality of sleep, appetite, mood, and concentration.

RESULTS

Of the 58 patients with psychiatric disorders, 44 patients had rapid cycling bipolar disorders characterized by manic, hypomanic, or mixed episodes. Eighteen patients had previously failed to respond to lamotrigine and/or gabapentin in addition to conventional mood stabilizers. Fourteen were Bipolar I, six Bipolar II, and seven mixed, ten patients had cyclothymic disorder, seven had bipolar disorder not otherwise specified. Of the remaining 14 patients, nine had schizoaffective disorder, three patients had dementia and two had psychosis. Mean duration of TPM treatment was 16.0 weeks; mean TPM dosage approximately 200 mg/day. Thirty-six of 58 (62%) patients exhibited marked or moderate improvement, usually within days or weeks. Twenty-three of 44 (52%) patients with bipolar affective disorders showed marked or moderate improvement. Minimal/no improvement was observed in 16; six were rated as worse. Adverse events included delirium in one patient with Bipolar Disorder Type I who overmedicated with TPM (800 mg) and tranylcypromine sulfate (170 mg) combined with alcohol. Other adverse effects were minor and included: paresthesias, somnolence, fatigue, impaired concentration and memory, nausea, and diarrhoea.

LIMITATIONS

This study was performed in a nonrandom open and retrospective fashion. Therefore, any findings are limited by the design of this study.

CONCLUSION

TPM may be useful in patients with mood disorders unresponsive to traditional therapy and warrants further clinical investigation.

Pathophysiological mechanisms of genetic absence epilepsy in the rat

Generalized non-convulsive absence seizures are characterized by the occurrence of synchronous and bilateral spike and wave discharges (SWDs) on the electroencephalogram, that are concomitant with a behavioral arrest. Many similarities between rodent and human absence seizures support the use of genetic rodent models, in which spontaneous SWDs occur. This review summarizes data obtained on the neurophysiological and neurochemical mechanisms of absence seizures with special emphasis on the Genetic Absence Epilepsy Rats from Strasbourg (GAERS). EEG recordings from various brain regions and lesion experiments showed that the cortex, the reticular nucleus and the relay nuclei of the thalamus play a predominant role in the development of SWDs. Neither the cortex, nor the thalamus alone can sustain SWDs, indicating that both structures are intimely involved in the genesis of SWDs. Pharmacological data confirmed that both inhibitory and excitatory neurotransmissions are involved in the genesis and control of absence seizures. Whether the generation of SWDs is the result of an excessive cortical excitability, due to an unbalance between inhibition and excitation, or excessive thalamic oscillations, due to abnormal intrinsic neuronal properties under the control of inhibitory GABAergic mechanisms, remains controversial. The thalamo-cortical activity is regulated by several monoaminergic and cholinergic projections. An alteration of the activity of these different ascending inputs may induce a temporary inadequation of the functional state between the cortex and the thalamus and thus promote SWDs. The experimental data are discussed in view of these possible pathophysiological mechanisms.