Clobazam Has Equivalent Efficacy to Carbamazepine and Phenytoin as Monotherapy for Childhood Epilepsy

Summary: Purpose: To compare the effectiveness of mono-therapy clobazam (CLB) to carbamazepine (CBZ) and phenytoin (PHT) in children with epilepsy.
Methods: Children aged 2–16 years with newly diagnosed epilepsy or previous failure of one drug (for poor efficacy or side effects) were assigned to one of two study arms and then randomized–CLB versus CBZ or CLB versus PHT. Eligible children had partial epilepsies or only generalized tonic-clonic seizures. After a drug initiation protocol, monotherapy treatment mimicked the usual routines used by Canadian child neurologists. Blinding used a "double dummy" technique with blinded medication serum levels (6–point scale). Intention to treat analysis using survival curves assessed the primary end-point–length of retention on the initial medication during the year after randomization.
Results: Fifteen centers entered 235 patients: 159 randomized to CLB versus CBZ and 76 to CLB versus PHT. Altogether, in all study arms, 119 received CLB, 78 CBZ, and 38 PHT. Overall, 56% continued to receive the original medication for l year with no difference between CLB and standard therapy (CBZ and PHT). Seizure control was equivalent for all three medications, as were side effects. PHT and CBZ induced more biologic side effects, such as rash, while CLB induced slightly more behavioral effects. Tolerance developed in 7.5% of patients receiving CLB, 4.2% with CBZ and 6.7% with PHT.
Conclusions: CLB should be considered as "first line" monotherapy along with CBZ and PHT for all partial and selected generalized childhood epilepsies.     

Dose–Response Study of Vigabatrin as Add-On Therapy in Patients with Uncontrolled Complex Partial Seizures

Summary: Purpose: This placebo-controlled, randomized, double-blind, multicenter study examined the efficacy and safety of three daily doses of vigabatrin (VGB; 1, 3, or 6 g) as add-on therapy in 174 patients with previously uncontrolled complex partial seizures with or without secondary generalization.
Methods: A 12-week pretreatment assessment period was followed by drug therapy with a 6-week titration period and a 12-week maintenance phase.
Results: VGB doses of 3 and 6 g/day reduced median monthly frequency of seizures by 4.3 and 4.5 seizures, respectively, compared with 0.2 seizures for placebo (p = 0.0001). The percentages of patients classified as therapeutic successes (≤50% reduction in seizure frequency) were 7% for placebo and 24, 51, and 54% for patients taking daily VGB doses of 1, 3, and 6 g, respectively; the comparison with placebo was significant for all treatment groups. The linear trend for dose response was highly significant (p ≥ 0.0001) for both median monthly seizure frequency and therapeutic success. Vigabatrin was well tolerated, causing no clinically significant changes in laboratory parameters, brain magnetic resonance imaging, evoked potentials, cognitive function, or psychosocial tests. Fatigue, drowsiness, and dizziness were the most common treatment-related adverse events in all treatment groups. Dropouts due to adverse events were higher in the 6-g/day group.
Conclusions: VGB was significantly more effective than placebo as add-on therapy in reducing seizure frequency. VGB at 3 and 6 g/day produced the best efficacy: however, adverse events may limit the use of the 6-g/day dose in some patients.     

Anticonvulsant Action of a 1,5-Benzodiazepine, Clobazam, in Reflex Epilepsy

Clobazam, an anxiolytic 1,5-benzodiazepine, has been evaluated as an anticonvulsant in 2 animal models. In mice showing sound induced seizures, clobazam, 1--4 mg/kg, i.p., blocked seizure responses for 1--2 hr. In Senegalese baboons Papio papio showing photically induced myoclonus or seizures, clobazam, 2--12 mg/kg, i.v., totally prevented such responses for up to 6 hr. In baboons pretreated with allylglycine, 170--185 mg/kg, a similar but briefer protection was induced by clobazam. Neurological toxicity was not prominent (transient, slight nystagmus after clobazam, 2--6 mg/kg; muscular hypotonia after clobazam, 12 mg/kg). The possibility that 1,5-benzodiazepines are superior to 1,4-benzodiazepines in the therapy of epilepsy requires clinical investigation.     

Clobazam in Therapy-Resistant Patients with Partial Epilepsy: A Double-Blind Placebo-Controlled Crossover Study

Clobazam was compared with placebo as antiepileptic adjunct medication in 129 therapy-resistant epileptic patients who were mainly suffering from complex partial seizures. The study was performed in five European countries according to a double-blind crossover design lasting 7 months. Two treatment periods of 3 months (1 month adjustment and 2 months maintenance medication) were separated by one medication switch-over month. The difference in seizure reduction between clobazam and placebo was significant (p less than 0.05). Nineteen percent of patients receiving clobazam became seizure-free during the maintenance dose period. In contrast, freedom from seizures was not observed in any placebo patient. Electroencephalogram (EEG) signs, mood ratings, and global impressions also indicated therapeutic effects of clobazam in epilepsy. The most frequent adverse reactions to clobazam were drowsiness and dizziness. However, the sedative effects of clobazam seemed to be less pronounced in comparison with other benzodiazepines. The study gives evidence of the therapeutic value of clobazam as adjunct medication in therapy-resistant partial seizures. The use of clobazam as monotherapy and long-term treatment, as well as the particular seizure response pattern to clobazam, has to be further investigated.     

Tiagabine: Efficacy and Safety in Adjunctive Treatment of Partial Seizures

PURPOSE: To assess the efficacy and safety of tiagabine (TGB), a new antiepileptic drug (AED), as add-on therapy in patients with refractory partial seizures. METHODS: This response-dependent study used an open-label screening phase (in which patients were titrated to their optimal TGB dose, < or =64 mg/day) followed by a double-blind, placebo-controlled, crossover phase. Initial eligibility criteria included (a) seizures inadequately controlled by existing AEDs, and (b) six or more partial seizures during an 8-week baseline period. Patients showing benefit from TGB (> or =25% reduction in total seizure rate relative to baseline) were eligible for randomization into the double-blind phase, which comprised two 7-week assessment periods separated by a 3-week crossover period. RESULTS: Forty-four (50%) of the 88 enrolled patients entered the double-blind phase of the study during which there were significant reductions compared with placebo in all partial (p < 0.01), complex partial (p < 0.001), and secondarily generalized tonic-clonic seizure rates (p < 0.05). Thirty-three percent of patients experienced a reduction of > or =50% in the all partial seizure rate. Eight (22%) patients receiving TGB during the double-blind phase reported adverse events, of which dizziness and incoordination were the most frequent. Three patients withdrew from treatment during the double-blind phase because of adverse events; two during treatment with TGB and one during treatment with placebo. TGB did not affect plasma concentrations of other coadministered AEDs. CONCLUSIONS: TGB was significantly better than placebo in terms of seizure rate reduction and was generally well-tolerated in patients with difficult to control seizures.     

Clinical Efficacy of Topiramate as Add-On Therapy in Refractory Partial Epilepsy: The European Experience

Summary: In three randomized, double-blind, placebo-controlled add-on European trials, target daily topiramate (TPM) dosages of 400, 600, and 800 mg/day (200, 300, and 400 mg bid) were evaluated in adults with refractory partial seizures with or without becoming secondarily generalized. Median reductions from baseline in monthly seizure rate were 41% with TPM 400 mg/day vs. 1% with placebo ( n = 0.065), 46% with TPM 600 mg/day compared to -12% (a 12% increase) with placebo ( p ≤ 0.005), and 36% with TPM 800 mg/day versus –18% (an 18% increase) with placebo ( p ≤ 0.001). Differences between TPM and placebo with respect to percent responders (percent of patients demonstrating a 50% or greater reduction in seizures) significantly favored TPM ( p ≤ 0.05) at all three target dosages. Significant reductions in secondarily generalized tonic-clonic seizures compared to placebo were also observed with 400 mg/day ( p = 0.002) and 800 mg/day ( p < 0.05) of TPM. TPM appears to be a promising new antiepileptic drug for use as adjunctive therapy in adults with refractory partial epilepsy.     

Sudden Unexplained Death Among Subjects with Refractory Epilepsy

Summary: Purpose : To address concerns about possible increases in rates of sudden unexplained death (SUD) after use of new anticonvulsants, more information on the rate of SUD among subjects with refractory epilepsy is needed to provide a comparison.
Methods : We conducted a study to estimate the incidence of SUD among subjects younger than 50 years with refractory epilepsy, by using information from the General Practice Research Database (GPRD) in the United Kingdom. For the purposes of this study, subjects receiving two or more anticonvulsant drugs concurrently were considered to have refractory epilepsy. Potential cases of SUD were identified from the computer records, and clinical records for these subjects were reviewed by two specialists in SUD in epilepsy.
Results : Fifteen subjects (eight male, seven female) of the 4,150 subjects with refractory epilepsy were considered to have definite/probable or possible SUD.
Conclusions : The overall incidence rate of SUD in the population was 2.2 per 1,000 person-years (95% CI, 1.3–3.6). The rate for subjects with highly probable SUD was 1.5 per 1,000 person-years (95% CI, 0.8–2.7).     

Altered Expression of Synaptotagmin I In Temporal Lobe Tissue of Patients With Refractory Epilepsy

Synaptotagmin I is a key synaptic protein involved in both exocytosis and endocytosis. We aimed to investigate Synaptotagmin I expression in the anterior temporal neocortex of epilepsy patients, and to explore the possible role of Synaptotagmin I in refractory epilepsy. In the present study, 30 epilepsy patients were divided into refractory epilepsy and non-refractory epilepsy groups, another 15 histologically normal anterior temporal lobes from head trauma patients were used as control group. The results were compared among different groups. The findings were consistently observed using immunohistochemistry, immunofluorescence, and Western blotting technique. Synaptotagmin I was mainly expressed in the cytoplasm and cytomembrane of neurons. The expression of Synaptotagmin I in refractory epilepsy group was significantly higher than that in the control and non-refractory epilepsy groups. These findings provide new information in the epileptogenesis of refractory epilepsy, and suggest that Synaptotagmin I might be involved in human refractory epilepsy. Further studies will be required to elucidate the mechanism by which Synaptotagmin I plays role in refractory epilepsy. Zheng Xiao and Yun Gong contributed equally to this work.     

Myoclonus in Epilepsy Patients with Anticonvulsive Add-On Therapy with Pregabalin

PURPOSE: To report on the occurrence of myoclonus in patients receiving pregabalin (PGB) for the treatment of focal epilepsy. METHODS: Clinic records of 19 patients who were consecutively enrolled at a tertial referral epilepsy center in a randomized, double-blind and/or open add-on study with PGB were reviewed. RESULTS: In four patients treated with PGB, focal myoclonus newly developed. The side effect appeared with PGB doses of 50-600 mg/day; the intensity showed some dose dependency. All patients had medically refractory focal epilepsy and received other antiepileptic drugs (AEDs) besides the study medication. One patient showed focal myoclonic jerks of the left arm, whereas the other patients developed multifocal myoclonus. Polygraphic studies including electromyogram (EMG)-triggered back-averaging of the EEG in the patient with the highest frequency of myoclonic jerks showed no visible correlate of the myoclonus. In this patient, frequency and intensity of myoclonic jerks significantly decreased after dose reduction of PGB. In the other cases, myoclonus was only subtle and did not significantly interfere with daily activities, so that a dose reduction of PGB was not considered necessary. CONCLUSIONS: These data indicate a relatively high incidence (four of 19) of myoclonus associated with PGB therapy. The rate seems to be at least as high as reported in patients receiving the structurally similar anticonvulsant gabapentin.     

High-Dose Phenytoin in the Treatment of Refractory Epilepsy

Refractory, long-standing, high-frequency epilepsy was successfully managed with high-dose phenytoin treatment. Side effects were observed in only three patients and were easily corrected. Most of the patients had partial seizures, but many also had a myoclonic component. Emphasis was placed on monotherapy whenever possible. Results, interpretation of serum levels, and toxic reactions to phenytoin are discussed.     

Adjunctive Therapy in Resistant Epilepsy

Summary: : It is now established that the overall prognosis for epilepsy is good and that remission will occur in at least 75% of patients following adequate treatment with monotherapy. Patients who fail to respond to monotherapy, who are not suitable for surgery, and who continue to have frequent seizures may have to be considered for an alternative drug regimen. A review of the literature indicates that complete seizure control with adjunctive treatment is rare, but improved seizure control can be obtained in up to 40% of patients. In a study of clobazam as adjunctive treatment, 60% (N = 20) of our patients responded to treatment initially and 33% maintained an improvement over an 18-month period. In 31 patients who failed to respond to carbamazepine as monotherapy, primidone (N = 16) or valproate (N = 15) were prescribed as adjunctive treatment. One patient obtained complete freedom from seizures and 14 (45%) had a > 50% reduction in seizure frequency. Suggested indications for the use of additive treatment in epilepsy are discussed.     

International Experience with Tiagabine Add-On Therapy

Summary: Tiagabine (TGB) hydrochloride is a novel antiepileptic drug (AED) that is a potent and specific inhibitor of γ-aminobutyric acid (GABA) uptake into glial and neuronal elements. In accordance with medical and regulatory standards, the clinical development program for TGB as an AED has assessed the value of TGB in add-on treatment, focusing mainly on partial seizures, including secondarily generalized seizures. Five add-on, placebo-controlled trials and six non-comparative, open-label, long-term multicenter trials have been or are being conducted in Australia, Europe, and the U.S.A. The results of these trials, involving 2,261 patients, indicate that TGB has efficacy as add-on therapy in patients with epilepsy difficult to control with existing AEDs. Efficacy of TGB is also sustained with long-term treatment. A clear dose-response has been demonstrated, and the minimal effective dose level is 30 mg. TGB is also tolerated, and with long-term therapy no new or more severe types of adverse events develop. These studies have included a wide age range of patients, including adolescents and the elderly.     

Refractory Childhood Epilepsy and Factors Related to Refractoriness

Summary: To clarify the characteristics of refractory childhood epilepsy, we compared recent refractory cases and those of approximately 15 years ago, all of which were seen at the Okayama University Hospital. We also analyzed predictive factors related to refractoriness in the recent refractory cases. Among the recent refractory cases, the proportion of localization-related epilepsies increased, and the proportion of generalized epilepsies decreased compared to historical cases. In generalized epilepsies, the proportion of cases with Lennox-Gastaut syndrome decreased to less than half. In localization-related epilepsies, the proportion of cases with frontal lobe epilepsy increased. The proportion of cases with unknown causes decreased to less than half. Of the cases with known causes, postencephalitis/postencephalopathy and focal cortical malformation, including tuberous sclerosis, accounted for most of the cases. More of the recent refractory cases were treated with high-dose AED monotherapy, compared to more poly-therapy in the cases of 15 years earlier. The following factors were related to future refractoriness: less than 1 year of age at onset of seizures, the presence of underlying pathology, status epilepticus, changes in type of epilepsy during the clinical course, and neonatal seizures. Regarding EEG findings of cases that had localization-related epilepsies at the end of follow-up, focal spike-waves associated with diffuse spike-waves on the first EEGs indicated future refractoriness.     

左乙拉西坦添加治疗难治性癫癎的疗效和安全性分析

目的:探讨左乙拉西坦添加治疗难治性癫痫的疗效和安全性。方法:回顾性分析了35例左乙拉西坦添加治疗的难治性癫痫患者,随访3～18个月,观察其疗效及不良反应。结果:左乙拉西坦添加治疗难治性癫痫总有效率为48.6%,对部分性发作和全面性发作的疗效无显著差异。不良反应发生率为31.5%,无严重不良反应。结论:左乙拉西坦是一种安全有效的难治性癫痫治疗药物,可以用于难治性癫痫的添加治疗。     

The Use of Clobazam, Midazolam, and Nitrazepam in Epilepsy

Summary: The benzodiazepines clobazam (CLB), midazolam (MDL), and nitrazepam (NZP) all have proven efficacy in epilepsy management, but their differences in physical properties, pharmacokinetic characteristics, side-effect profiles, and intrinsic antiepileptic activity lead to different indications for use. CLB is a 1,5-benzodiazepine that causes less sedation than 1,4-benzodiazepines but offers improved antiepileptic action. It has been extensively studied in both open and controlled trials as antiepileptic therapy for a variety of seizure types. It is now widely used in European countries as adjunctive therapy for partial and secondarily generalized seizures. Clinical trial experience, however, indicates that more than 50% of patients develop tolerance to the antiepileptic effects of CLB. Therefore, CLB has had a relatively limited role as a routine antiepileptic drug. It has further use as an intermittent or occasional therapy, in which tolerance is of less concern. MDL is a water-soluble 1,4-benzodiazepine. It is the only drug in this class that is useful when given by i.m. injection, although MDL can also be administered rectally or by i.v. bolus or infusion. MDL has a very short elimination half-life and is used for emergency treatment of status epilepticus or acute seizures. NZP has reported efficacy in acute epilepsy, although it is not routinely used for this situation. Although there have been no controlled studies of NZP for chronic epilepsy treatment, this drug appears to be moderately effective in a wide range of seizure types. NZP is predominantly used in children with severe epilepsy intractable to conventional medications.