Selection of drugs for the treatment of epilepsy

Antiepileptic drug selection is based on efficacy for specific seizure types and epileptic syndromes. For idiopathic generalized epilepsies with absence, tonic-clonic, and myoclonic seizures, the drug of choice is valproate. Secondary generalized epilepsies with tonic, atonic, and other seizure types are difficult to treat with any single drug or combination of drugs. The drugs of choice for absence seizures are ethosuximide and valproate. For control of tonic-clonic seizures, any of the other major antiepileptic drugs can be effective. If valproate cannot be used, carbamazepine, phenobarbital, phenytoin, or primidone is effective, but ethosuximide or a benzodiazepine needs to be added to control associated absence or myoclonic seizures. The drugs of first choice for partial epilepsies with partial and secondarily tonic-clonic seizures are carbamazepine and phenytoin. Increasing evidence suggests that valproate may be a third alternative. Phenobarbital and primidone are second choice selections because of side effects. A combination of two of these five major antiepileptic drugs may be necessary for inadequately controlled patients. Other epilepsy syndromes such as neonatal and infantile epilepsies, febrile epilepsy, and alcoholic epilepsy require specific drug treatment. For all these seizure types and epilepsy syndromes, treatment ultimately must be selected to provide maximal efficacy and minimal adverse effect for each individual patient.     

A multicentre comparative trial of sodium valproate and carbamazepine in adult onset epilepsy. Adult EPITEG Collaborative Group.

The long-term efficacy and safety of sodium valproate and carbamazepine in adult outpatients with newly diagnosed primary generalised or partial and secondarily generalised seizures were compared in a randomised, open, multicentre study at 22 neurology outpatient clinics. Patients were randomised to oral sodium valproate (Epilim EC enteric coated 200 mg tablets twice daily, n = 149) or oral carbamazepine (100 mg twice daily increasing to 200 mg twice daily in week 2, n = 151) and followed up for three years. If clinically necessary, dosages were regularly increased until seizures were controlled or toxicity developed. Sodium valproate and carbamazepine controlled both primary generalised and partial seizures equally effectively overall. Significantly more patients on sodium valproate than carbamazepine (126/140 (90%) v 105/141 (75%), p = 0.001) remained on randomised treatment for at least six months. Skin rashes occurred significantly more often in carbamazepine recipients than in sodium valproate recipients (11.2% v 1.7%, p < 0.05) and carbamazepine was associated with a higher withdrawal rate because of adverse events (15% v 5% on sodium valproate) in the first six months of treatment. There was no difference between the drugs in the rate of withdrawal because of poor seizure control at any stage, regardless of seizure type. At the end of the three year trial period, over 70% of the available patients were still on randomised treatment or had recently stopped treatment after achieving full seizure control. Sodium valproate and carbamazepine were both associated with a high degree of overall seizure control regardless of seizure type and both have good long-term tolerability in adult patients with newly diagnosed epilepsy. Recommendations are made for a higher initial dosage regime for sodium valproate in partial seizures.     

The dynamics of drug treatment in epilepsy: an observational study in an unselected population based cohort with newly diagnosed epilepsy followed up prospectively over 11-14 years

OBJECTIVES: To study prospectively long term dynamics and patterns of treatment in a population based cohort of patients with newly diagnosed epilepsy. METHODS: 564 patients with definite epilepsy entered the UK National General Practice Study of Epilepsy (NGPSE), between 1984 and 1987, and were prospectively followed up for between 11-14 years. RESULTS: Treatment was started in 433 (77%) patients. Only 15% of single seizure patients had medication prescribed initially, although due to high seizure recurrence, more than 70% ultimately received antiepileptic medication. 209/564 patients (37%) were on drug therapy for epilepsy at the time of last follow up. 168/564 patients (30%) have stayed continuously on medication and another 41/564 patients (7%) restarted drug therapy because of seizure recurrence, having withdrawn medication. 98/209 (47%) of those on treatment are known to be in 5 year terminal remission. Phenytoin (29%) and carbamazepine (27%) were the most commonly preferred first line drugs followed by valproate (15%). Less than half of treated patients with partial seizures received carbamazepine as a first line drug and less than a third with generalised seizures were prescribed valproate as first choice drug. Nine out of 31 (29%) patients with one or more seizures a week at last follow up had never tried a second drug and only seven (23%) had tried four or more drugs. 11% of all treatment changes involved a new antiepileptic drug. Treatment changes were associated with low terminal remission rates. CONCLUSIONS: Out of 30 000 patients with newly diagnosed epilepsy every year in the United Kingdom, about 6000 have inadequate seizure control in the long term. About a third of the patients in this group have one or more seizures every month. Only two thirds of these patients with frequent seizures are likely to switch medication to try and achieve better seizure control. There is probably still considerable room for improvement in prescribing practice in the United Kingdom.     

Seizure-inducing effects of antiepileptic drugs: a review

Seizure-inducing effects can be observed in the treatment of epileptic patients with antiepileptic drugs (AED). This may be a paradoxical reaction (for example the increase of complex focal seizures due to carbamazepine, vigabatrin or phenytoin treatment) or a result of AED-induced encephalopathy (commonly induced by valproate in patients with complex focal seizures). A seizure increase during intoxication with AEDs is a rare phenomenon, thus, it is not directly related to this condition. An incorrect choice of drugs in the treatment of an epileptic syndrome or seizure type may provoke seizures (as for example the provocation of absences due to carbamazepine or phenytoin). The possible seizure-inducing effect of AEDs has to be differentiated from seizure occurrence due to the natural course of epilepsy. This may be especially difficult in patients suffering from West syndrome or Lennox-Gastaut syndrome, in whom seizure frequency may vary even without medication. However, especially in these patients, drug-induced worsening of seizure manifestation is often observed. In general, a seizure-inducing effect of antiepileptic drugs has to be considered when a seizure increase is observed soon after the initiation of therapy, when a stepwise increase of the dosage is followed by a further increase of seizures, a decrease of seizures is seen with tapering of the dosage and a renewed increase of seizures can be observed after this therapy has been reestablished. Finally, one knows that the clinical condition of encephalopathy due to valproate or carbamazepine is accompanied by seizure increase. In spite of these clinical aspects, the underlying mechanisms of seizure increase mostly remain unclear. From animal experiments it is obvious that especially carbamazepine and phenytoin may provoke generalized seizures as absences or myoclonic seizures. A seizure increase during vigabatrin therapy has been attributed to the increase of the cerebral amount of gamma-amino-butyric acid, which is known to possibly exhibit inhibitory or excitatory neuronal effects. The occurrence of tonic seizures in patients with Lennox-Gastaut syndrome has been attributed to the sedative effect of the drugs; however, this conclusion is controversial. From a clinical point of view, one should consider young age of the patient, mental retardation, antiepileptic polytherapy, high frequency of seizures or prominent epileptic activity in the electroencephalogram previous to medication as risk factors for a possible seizure-inducing effect of antiepileptic drugs.     

Prognosis of chronic epilepsy with complex partial seizures.

Clinical features associated with a successful or unsuccessful response to high dose antiepileptic drug therapy were evaluated prospectively in 82 patients with chronic complex partial seizures. Complete seizure control was observed during high dose drug therapy in 18 patients at plasma concentrations of either 9-35 micrograms/ml phenytoin, 32 and 40 micrograms/ml phenobarbitone, 8 micrograms/ml carbamazepine, or a combination of 25 micrograms/ml phenobarbitone and 4 micrograms/ml carbamazepine. Patients who became free of seizures had a markedly lower number of three seizures (range: 1-29) in the year before the high dose treatment as compared to 40 seizures (range: 3-328) in patients with an increased or unchanged seizure frequency (p less than 0.0001). Complex partial seizures without automatism were found only in patients with complete seizure control (22%). Patients whose seizures remained uncontrolled more frequently gave a history of severe depression or psychotic episodes, clusters of complex partial seizures, two or more seizures per day, and an aura preceding the attack. The results suggest that taking a careful history will uncover clinical features associated with a successful or unsuccessful response to high dose antiepileptic drug therapy in an epileptic out-patient with chronic complex partial seizures.     

A prospective study between carbamazepine, phenytoin and sodium valproate as monotherapy in previously untreated and recently diagnosed patients with epilepsy.

One hundred and eighty one patients with previously untreated epilepsy were randomised to sodium valproate, phenytoin or carbamazepine as monotherapy and followed up for a median period which ranged from 14 to 24 months. All three drugs were highly effective in the control of generalised seizures but less effective for partial seizures. Excellent or good control was achieved with therapeutic levels of sodium valproate and carbamazepine, but with subtherapeutic levels of phenytoin.     

Teratogenicity of antiepileptic drug combinations with special emphasis on epoxidation (of carbamazepine)

A higher rate of congenital anomalies has been found after prenatal exposure to some combinations of antiepileptic drugs than to the separate drugs. In an earlier study a rate of 58% congenital anomalies was found among infants exposed to carbamazepine plus phenobarbitone plus valproate. In this study an attempt was made to determine whether this specific combination of drugs has teratogenic activity due to metabolic interaction. The epidemiological data were analyzed further. The high rate of congenital anomalies after prenatal exposure to this combination could not be explained by the effects of one or two of these drugs only, nor by additional exposure to phenytoin. Assuming that metabolic interaction in the arene oxide pathway resulting in accumulation of epoxide intermediates of antiepileptic drugs could be responsible for teratogenesis, the ratio of carbamazepine to carbamazepine-10, 11-epoxide concentrations in serum was determined in adult patients with epilepsy who were treated with carbamazepine only and with different combinations of phenobarbitone, valproate, and/or phenytoin. For carbamazepine monotherapy the mean ratio was 8.19. For all combinations lower ratios were found, indicating accumulation of carbamazepine-10,11-epoxide. The combination of carbamazepine, phenobarbitone, valproate, and phenytoin showed the lowest ratio (1.94), followed by carbamazepine, valproate, and phenytoin and by carbamazepine, phenobarbitone, and valproate (2.81 and 3.18, respectively). These results give rise to the question of whether the combination of carbamazepine, phenobarbitone, valproate, and/or phenytoin has teratogenic activity by accumulation of carbamazepine-10,11-epoxide or other epoxide intermediates, and stress the need to take metabolic interactions into account when investigating the teratogenic activity of antiepileptic drugs.     

The cognitive effects of oxcarbazepine versus carbamazepine or valproate in newly diagnosed children with partial seizures

OBJECTIVE: To investigate the effect of oxcarbazepine against standard antiepileptic drug therapy (carbamazepine and valproate) on cognitive function in children and adolescents (aged 6 to <17 years) with newly diagnosed partial seizures. METHODS: A multicentre, open-label, randomised, active-control, three-arm, parallel-group, 6-month study. The primary cognitive variable, the Computerized Visual Searching Task (CVST), assessed mental information processing speed and attention. Secondary variables included additional tests assessing psychomotor speed, alertness, memory and learning, and non-verbal intelligence. RESULTS: Of 112 patients randomised, 99 completed the study. The dropout rate was 11.6%; 13 patients discontinued due to adverse events (n=5) or unsatisfactory therapeutic effect (n=8). Mean CVST time decreased in all groups, indicating an improvement of mental processing speed and no cognitive impairment in any treatment group. No statistically significant difference was observed between oxcarbazepine and combined carbamazepine/valproate. Analysis of secondary variables did not show statistically significant differences between oxcarbazepine, carbamazepine and valproate. Analysis of intelligence test results showed that the number of correct answers increased at end point in all groups. The percentage of patients remaining seizure free throughout treatment was comparable across all groups (oxcarbazepine 58%; carbamazepine 46%; valproate 54%; carbamazepine/valproate 50%). The most common adverse events were fatigue and headache for oxcarbazepine, fatigue and rash for carbamazepine, and headache, increased appetite and alopecia for valproate. CONCLUSION: Oxcarbazepine treatment over 6 months does not display any differential effects on cognitive function and intelligence in children and adolescents with newly diagnosed partial seizures relative to standard antiepileptic drug therapy. No impairment in cognitive function was observed in any treatment group over a 6-month period.     

The influence of seizure type on the efficacy of plasma concentrations of phenytoin, phenobarbital, and carbamazepine

Plasma concentrations of phenytoin, phenobarbital, or carbamazepine were monitored prospectively during successful single-drug therapy in 78 patients who had various types of epileptic seizures. Mean plasma concentrations necessary for complete control of tonic-clonic seizures alone were as follows: phenytoin, 14 micrograms/mL (n = 28); phenobarbital, 18 micrograms/mL (n = 10); and carbamazepine, 5.5 micrograms/mL (n = 2). Epilepsy with simple or complex partial seizures alone or together with tonic-clonic seizures was completely controlled at the following plasma concentrations: phenytoin, 23 micrograms/mL (n = 25); phenobarbital, 37 micrograms/mL (n = 5); and carbamazepine, 7 micrograms/mL (n = 7). Higher plasma concentrations of phenytoin, phenobarbital, and carbamazepine are necessary for control in epilepsy with simple or complex partial seizures compared with epilepsy with tonic-clonic seizures alone. The efficacy of plasma concentrations of phenytoin, phenobarbital, and carbamazepine varies with the type of seizure.     

Use of antiepileptic drugs in the treatment of epilepsy in people with intellectual disability

The main principles of antiepileptic drug treatment of epilepsy in patients with intellectual disability are basically the same as for other patients with epilepsy. However, some specific issues need to be taken into account These are primarily associated with the diagnostic difficulties of epilepsy in this population. In addition, a number of other relevant issues, including the degree and location of brain lesion, the nature of the underlying disease, the higher frequency of difficult-to-treat epilepsies, the additional intellectual impairment caused by inappropriate antiepileptic medication, or by frequent and prolonged seizures, the appropriate use of monotherapy versus rational polytherapy, and the use of broad-spectrum antiepileptic drugs will be discussed in the present paper. Although the goals of treatment are to keep the patient seizure-free and alert while preventing possible mental deterioration, we have to accept compromises between these primary goals in many cases. Some people with epilepsy and intellectual disability are very vulnerable to insidious neurotoxic effects; for example, sedative effects caused by phenobarbital, or cognitive and/or cerebellar dysfunction caused by long-term phenytoin, especially together with other drugs. Because of the adverse effects of phenobarbital and phenytoin, these drugs are no longer recommended as a first-choice drugs when long-term antiepileptic medication is required. In primary generalized tonic-clonic seizures, valproate, oxcarbazepine/carbamazepine and lamotrigine are recommended in this order of preference. The corresponding recommendations are: in typical absences, valproate, ethosuximide and lamotrigine; in atypical absences, valproate and lamotrigine; in juvenile myoclonic epilepsy, valproate, lamotrigine and clobazam; in infantile spasms vigabatrin, ACTH and valproate; in Lennox-Gastaut syndrome, valproate, lamotrigine and vigabatrin; in atonic seizures, valproate and lamotrigine; in simple and complex partial seizures with or without secondary generalization, oxcarbazepine/carbamazepine, valproate/ vigabatrin and lamotrigine; and in status epilepticus lorazepam, diazepam and clonazepam together with phenytoin or fosphenytoin. In cases of poor response to the monotherapy recommended above, the following combinations may be indicated: in primary generalized tonic-clonic epilepsy, valproate and oxcarbazepine/ carbamazepine, or valproate and lamotrigine; in typical absences, valproate and lamotrigine, or valproate and ethosuximide; in juvenile myolonic epilepsy, valproate and lamotrigine, or valproate and clonazepam; and in partial epilepsies, add to the monotherapy one of the following drugs, vigabatrin, lamotrigine, gabapentin, tiagabine, topiramate, zonisamide or clobazam. So far, the order of preference of these new drugs remains undetermined. More data are needed on the efficacy and adverse effects of the new drugs based on controlled studies on patients with intellectual disability and epilepsy.     

Outpatient sleep recording during antiepileptic drug monotherapy

The effects of sleep and sleep deprivation on epilepsy are well known, but the effects of seizures and antiepileptic drugs (AEDs) on sleep have been less well studied. We recorded nocturnal sleep in 17 patients receiving antiepileptic monotherapy with ambulatory cassette EEG devices. Twelve patients had complex partial seizures and five had tonic-clonic convulsions. Two patients' seizures were largely nocturnal, and no seizures occurred during sleep recording. Five patients each were taking phenytoin (PHT), carbamazepine (CBZ), and valproate (VPA), and two were taking clonazepam (CZP), all with therapeutic serum levels and no toxic symptoms. Total sleep time was reduced, wakefulness increased, and sleep latency prolonged in partial seizures as compared with generalized epilepsy. REM sleep was reduced and its latency decreased in partial seizure patients. Both groups had decreased slow wave sleep; that of partial seizure patients was decreased more markedly. PHT increased sleep latency and decreased sleep time, and CBZ increased awakening and diminished slow wave and REM sleep. Patients taking VPA had slight reduction in slow wave sleep; those taking CPZ had decreased sleep and REM latencies. Epilepsy may affect nocturnal sleep, and the effects of partial and generalized seizure disorders may be different. AEDs may also have differential effects on nighttime sleep. These may prove important in the long-term management of epileptic patients.     

Lamotrigine Monotherapy in Newly Diagnosed Untreated Epilepsy: A Double-Blind Comparison with Phenytoin

PURPOSE: Lamotrigine is an effective add-on therapy against a range of epileptic seizure types. Comparative studies with carbamazepine (CBZ) as monotherapy in newly diagnosed epilepsy suggest similar efficacy. In this study, lamotrigine (LTG) and phenytoin (PHT) are compared. METHODS: In a double-blind parallel-groups study, 181 patients with newly diagnosed untreated partial seizures or secondarily or primary generalised tonic-clonic seizures were randomised to two treatment groups. One group (n = 86) received LTG titrated over 6 weeks from a starting dose of 100 mg/day. The other (n = 95) received PHT titrated from 200 mg/day. Treatment continued for < or =48 weeks. RESULTS: The percentages of patients remaining on each treatment and seizure free during the last 24 and 40 weeks of the study, and times to first seizure after the first 6 weeks of treatment (dose-titration period), did not differ significantly between the treatment groups. These were measures of efficacy. Time to discontinuation, a composite index of efficacy and safety, likewise did not distinguish between treatments. Adverse events led to discontinuation of 13 (15%) patients from LTG and 18 (19%) from PHT. The adverse-event profile for LTG was dominated by skin rash [discontinuation of 10 (11.6%) patients compared with five (5.3%) from PHT] rather than central nervous system side effects: asthenia, somnolence, and ataxia were each significantly more frequent in the PHT group. The high rate of rash with LTG was probably due to the high starting dose and may be avoidable. A quality-of-life instrument, the SEALS inventory, favoured LTG. Patients taking PHT showed the biochemical changes expected of an enzyme-inducing drug, whereas those taking LTG did not. CONCLUSIONS: LTG and PHT monotherapy were similarly effective against these seizure types in patients with newly diagnosed epilepsy. LTG was better tolerated, more frequently causing rash, but with a lower incidence of central nervous system side effects.     

Clinical Science

Pregabalin Drug Interaction Studies: Lack of Effect on the Pharmacokinetics of Carbamazepine, Phenytoin, Lamotrigine, and Valproate in Patients with Partial Epilepsy Martin J. Brodie, Elaine A. Wilson, David L. Wesche, Christine W. Alvey, Edward J. Randinitis, Edward L. Posvar, Neil J. Hounslow, Nicola J. Bron, G.L. Gibson, and Howard N. Bockbrader Pregabalin (Lyrica) is a new drug that has been approved in the EU as add‐on treatment for partial seizures, and as treatment of peripheral neuropathic pain, in adults. Because many patients with partial seizures require more than one antiepileptic drug (AED) to achieve the best seizure control they can, it is important to determine whether new drugs for treating partial seizures may interact with commonly used AEDs. This paper reports the results of several drug–drug interaction studies of pregabalin and commonly used AEDs. In these studies, pregabalin was given to patients who were each taking one AED, either valproate, phenytoin, lamotrigine, or carbamazepine, to treat their epilepsy. Adding pregabalin to monotherapy with valproate, phenytoin, lamotrigine, or carbamazepine had no effect on the concentrations in the blood of any of these four drugs. Likewise, when concentrations of pregabalin in the blood were measured in these same patients, the concentrations were similar to those seen in the blood of subjects from earlier studies who had received pregabalin by itself. These findings indicate that pregabalin does not interact with any of these four common AEDs. The combinations of pregabalin with either valproate, phenytoin, lamotrigine, or carbamazepine were generally well tolerated by the patients in these studies, and when side effects did occur, they were typically mild to moderate and resolved quickly. Together, these studies demonstrate that pregabalin may be safely added to therapy with valproate, lamotrigine, phenytoin, or carbamazepine without concern for drug–drug interactions.     

Results of a Nationwide Veterans Administration Cooperative Study Comparing the Efficacy and Toxicity of Carbamazepine,Phenobarbital, Phenytoin,and Primidone

Summary: : In 1985 a 5-year multicenter Veterans Administration Cooperative Study was completed that compared the efficacy and toxicity of phenobarbital, carbamazepine, phenytoin, and primidone in a double-blind prospective study design. A total of 622 patients, either previously untreated or undertreated, were entered into the study. Strict exclusion criteria limited confounding factors such as drug or alcohol abuse. Results showed that each of the four drugs used as monotherapy were similarly effective in the treatment of generalized tonic-clonic seizures, but carbamazepine was significantly more effective in the treatment of complex partial seizures as measured by 100% control. When the results for all four drugs were combined, the data showed that approximately 80% of the patients were adequately managed on monotherapy. Differences in toxicity were the most significant factor that discriminated between these four drugs. Both carbamazepine and phenytoin were associated with significantly lower incidences of intolerable side effects than were primidone or phenobarbital. A behavioral toxicity battery was performed whenever possible prior to administration of any antiepileptic drug and at 1, 3, 6, and 12 months after initiation of monotherapy. Significant differences in performance on all subtests of the battery were found between patients with epilepsy and a control group matched by age, sex, and education. When the differential effects of all four drugs on behavioral toxicity were compared, few statistically significant differences emerged. However, carbamazepine consistently produced fewer adverse effects on tests of attention/concentration and motor performance than did the other three antiepileptic drugs.     

Amantadine hydrochloride for refractory generalized epilepsy in adults

Amantadine hydrochloride has been shown in several open studies to benefit children with refractory generalized epilepsy. We used amantadine as adjunctive therapy in 10 adolescents and adults with generalized tonic-clonic, myoclonic, or absence seizures refractory to therapeutic levels of valproate, carbamazepine, phenytoin, and benzodiazepines. Seven patients were men and 3 were women aged 18-29 years, and 8 of 10 patients were mentally retarded. All patients had generalized epileptiform paroxysms on EEG, with generalized or absence seizure recorded in 9. Five patients had both absence and tonic-clonic seizures, and 2 had all three seizure types. Amantadine was added to the existing regimens in weekly increments to 400 mg/day. Two patients had greater than 90 per cent seizure reduction, both with vomiting and somnolence. Two patients had seizure reduction between 50 and 90 per cent, 1 with anorexia and sleepiness. Three patients had no change in seizures, and 3 had worse tonic-clonic seizures. Amantadine may have some antiepileptic efficacy of unknown mechanism, but it may worsen generalized tonic-clonic seizures and is likely to be of limited value in adults.     

Randomised controlled monotherapy trials: which comparators to use?

As approximately 50% of patients with newly diagnosed epilepsy achieve seizure remission after initial monotherapy, the selection of the first-choice drug to be used as the gold standard in randomised clinical trials is critical. Several first and second generation drugs have been used in regulatory and pragmatic monotherapy trials with similar efficacy but differing pharmacokinetic, tolerability, and safety profiles. None of the available compounds has an ideal profile and second generation drugs do not appear to present unequivocal advantages in this regard. Compared to first generation drugs, some newer generation antiepileptic drugs may be preferred as they have similar efficacy but lower potential for idiosyncratic reactions and drug interactions. However, more recent antiepileptic drugs also have limitations, which include lack of superiority and, in some cases, unbearable adverse effects. In this light, there are no standard criteria as a reference for the selection of the best comparator for new monotherapy trials. However, according to the recommendations of evidence-based guidelines, carbamazepine still represents the first-choice drug for patients with partial epilepsy. Ethosuximide may be an option for absence epilepsy. In contrast, for the treatment of patients with other generalised epilepsies, there is no clear indication of preferred drug, as valproate, which has been found to prevail over other compounds, should be withheld in women of childbearing age due to its teratogenic potential, and there is insufficient evidence to choose an alternative drug.     

Seizure type, antiepileptic drugs, and reproductive endocrine dysfunction in Indian women with epilepsy: a cross-sectional study

Background: There is paucity of data regarding occurrence of reproductive endocrine disorders in Asian women with epilepsy (WWE) on antiepileptic drug (AED) therapy. Purpose: To determine the occurrence of reproductive endocrine disorders in Indian WWE, by seizure type and the AED use. Methods: Consecutive 427 reproductive age WWE receiving various AEDs were screened for the occurrence of menstrual abnormalities, weight change, and hirsutism. Of these, 53 WWE with menstrual disturbances and/or hirsutism were further evaluated for ovarian morphology and reproductive hormonal profile. Results: Menstrual abnormalities and/or hirsutism were observed in 83 of 427 (19.4%) WWE irrespective of epileptic seizure type; of these, 50 (60.2%) received valproate, 21 (25.3%) received carbamazepine, 11 (13.3%) received phenytoin, and one (1.2%) received phenobarbitone as the primary AED. Almost half of valproate‐treated women had significant weight gain and obesity. Among 53 of 83 women evaluated further, 23.5% and 63.6% of valproate‐treated women, 25% and 58.3% of carbamazepine‐treated women, and none and 20% of phenytoin‐treated women had polycystic ovaries (PCO) and hyperandrogenemia (HA), respectively. Valproate‐treated women had significantly higher frequency of polycystic ovarian syndrome (PCOS) (11.8% vs. 2.5%, p < 0.0001) and mean serum testrosterone levels (1.78 vs. 1.36 ng/ml, p = 0.03), compared with women treated with other AEDs. Limitations: Limitations include small number of women in antiepileptic subgroups and a high drop out rate in women who underwent ultrasound and endocrinological investigations. Conclusion: Menstrual abnormalities, weight gain, obesity, and PCOS are frequent and significantly higher in WWE receiving valproate, independent of seizure type.     

Anticonvulsant drug actions on neurons in cell culture

Summary Two actions of clinically used antiepileptic drugs have been studied using mouse neurons in primary dissociated cell culture. The antiepileptic drugs phenytoin, carbamazepine and valproic acid were demonstrated to limit sustained high frequency repetitive firing of action potentials at free serum concentratons that are achieved in patients being treated for epilepsy. Furthermore, an active metabolite of carbamazepine also limited sustained high frequency repetitive firing while inactive metabolites of phenytoin and carbamazepine did not limit sustained high frequency repetitive firing. Phenobarbital and clinically used benzodiazepines limited sustained high frequency repetitive firing of action potentials, but only at concentrations achieved during the treatment of generalized tonic-clonic status epilepticus. Ethosuximide did not limit sustained high frequency repetitive firing even at concentrations four times those achieved in the serum of patients treated for generalized absence seizures. Phenobarbital and clinically used benzodiazepines enhanced postsynaptic GABA responses at concentrations achieved free in the serum during treatment of generalized tonic-clonic or generalized absence seizures. However, phenytoin, carbamazepine, valproic acid and ethosuximide did not modify postsynaptic GABA responses at therapeutic free serum concentrations. These results suggest that the ability of antiepileptic drugs to block generalized tonicclonic seizures and generalized tonic-clonic status epilepticus may be related to their ability to block high frequency repetitive firing of neurons. The mechanism underlying blockade of myoclonic seizures may be related to the ability of antiepileptic drugs to enhance GABAergic synaptic transmission. The mechanism underlying management of generalized absence seizures remains unclear.     

Rufinamide: a double-blind, placebo-controlled proof of principle trial in patients with epilepsy

OBJECTIVE: This was the first proof of principle clinical trial assessing the efficacy and safety of rufinamide as adjunctive therapy in epileptic patients. The pharmacokinetic (PK) profile of rufinamide was also determined. METHODS: Fifty patients with diagnoses of partial or primary generalized tonic-clonic seizures were enrolled in this 28-day double-blind, placebo-controlled, weekly rising dose (400-1600 mg/day) trial. PK profiles were obtained after administration of single-dose rufinamide prior to and after the Double-blind phase. RESULTS: In the evaluable patient population, seizure frequency decreased by 41% in the rufinamide group and increased by 52% in the placebo group (P=0.040). Thirty-nine percent (39%) of rufinamide-treated and 16% of placebo-treated patients experienced reduction in seizure frequency of at least 50% relative to baseline (P=0.096). SAFETY: Treatment-emergent adverse events (AEs) consisted mainly of neurologic signs and symptoms commonly associated with antiepileptic drugs (AEDs). PHARMACOKINETICS: At steady state, rufinamide reached a peak plasma concentration with a mean time (Tmax) of 3.4 h and a mean half-life (t1/2) of 7.3 h. No autoinduction of rufinamide metabolism occurred. Rufinamide did not influence the plasma concentration of carbamazepine, phenytoin or valproate when added to these single AED regimens. CONCLUSION: Rufinamide has been shown, in this proof of principle trial, to be safe and effective in reducing seizure frequency in epileptic patients with no relevant influence on the metabolism of other AEDs.