Gabapentin (Neurontin) as Add-on Therapy in Patients with Partial Seizures: A Double-Blind,Placebo-Controlled Study

Summary: A multicenter, double-blind, randomized, placebo-controlled study evaluated the efficacy and safety of gabapentin (Neurontin, GBP) as add-on therapy in 272 patients with refractory partial seizures who were receiving one to two standard antiepileptic drugs (AEDs). Efficacy assessments compared the frequency of partial seizures during the 12-week treatment phase (T) and the 12-week baseline period (B). The primary analysis compared data for patients receiving GBP 900 mg/day with placebo; the GBP 1,200-mglday group provided doseresponse data. Efficacy criteria were percentage of change in seizure frequency (PCH), responder rate (percentage of patients with ≥50% reduction in seizure frequency), and response ratio, where RRatio = (T B)/(T + B). Median PCH was–21.8% in the 900-mg/day group and ?17.8% in the 1,200-mg/day group as compared with ?0.3% in the placebo group. Responder rate was 22.9% in the 900-mg/day group and 10.1% in the placebo group (p = 0.020, Fisher's exact test). Adjusted mean Rratio was-0.136 in the 900-mg/day group and ?0.025 in the placebo group (p = 0.0046, analysis of variance ANOVA). Results showed slightly greater improvement for the 1,20-mg/day than for the 900-mg/day group (RRatio =?0.157, responder rate 28.0%). Adverse events (AE) occurred in 69% of patients in the 900-mg/day group and in 64% in the 1,200-mg/day group as compared with 52% in patients receiving placebo as add-on therapy. The most frequent AE among patients treated with GBP were somnolence, dizziness, and fatigue. Clinical laboratory evaluations showed no clinically important trends and no evidence of hepatic or hematopoietic effects. GBP is safe and effective in treating some patients with refractory partial seizures.     

Efficacy and Tolerance of Long-Term, High-Dose Gabapentin: Additional Observations

Summary: Gabapentin (GBP) has shown antiepileptic efficacy and good tolerance in clinical trials. Much remains to be learned about its clinical use. As a participating center in the US Gabapentin Study Group, we report observations that have practical implications for patient management. Twenty-three patients with intractable partial-onset seizures initiated open-label treatment after a blinded placebo-controlled add-on dose efficacy study. In the titration phase, GBP and concurrent antiepileptic drugs (AEDs) were adjusted to achieve optimal efficacy on maximally tolerated GBP doses. Nine patients had no significant improvement in seizure control and discontinued GBP. The remaining 14 patients were observed while treated long-term with stable-dose GBP and concurrent AEDs. Improvement was maintained as long as patients were followed: ≤4 years. The protocol-allowed upper dose limit, 2,400 mg/day, was well tolerated by 16 of 23 patients, indicating that higher doses may be tolerated. GBP discontinuation did not cause rebound increases in seizure frequency. The most common adverse events (AEs) (in 14 of 23) were similar to those induced by concurrent AEDs and responded to reduction of concurrent AEDs. Many patients reported positive psychostimulatory effects. These observations extend previous findings indicating that GBP is an effective and well-tolerated drug for treatment of partial-onset seizures.     

Gabapentin as Add-On Therapy in Children with Refractory Partial Seizures: A 12-Week, Multicentre, Double-Blind, Placebo-Controlled Study

PURPOSE: To evaluate the efficacy and safety of gabapentin (Neurontin; GBP) as add-on therapy for refractory partial seizures in paediatric patients aged 3-12 years. METHODS: After a 6-week baseline period, 247 patients (54 centres) entered a 12-week double-blind phase and were randomized to receive either GBP (t.i.d., titrated to 23-35 mg/kg/ day) or placebo. Seizure activity and type were recorded daily. Efficacy variables included Response Ratio (RRatio), responder rate, and percentage change in frequency (PCH) for all partial seizures; PCH and RRatio for individual types of partial seizures; and investigator and parent/guardian global assessments of seizure frequency and patient well-being. RESULTS: RRatio for all partial seizures was significantly lower (better) for GBP-treated patients (p = 0.0407). Responder rate favored GBP, but the difference between treatment groups was not statistically significant. Median PCH for all partial seizures for the GBP treatment group (-17.0%) was better than that for the placebo group (-6.5%). Median PCH for specific seizure types showed GBP to be most effective in controlling complex partial seizures (-35%) and secondarily generalized seizures (-28%) when compared with placebo (-12%, +13%, respectively). A greater percentage of GBP-treated patients exhibited improvement according to investigator and parent/guardian global assessments, with a statistically significant difference observed in the parent/guardian global assessment of seizure-frequency reduction (p = 0.046). Three GBP patients and one placebo patient were seizure free during the double-blind treatment period. GBP was well tolerated. CONCLUSIONS: GBP was effective and well tolerated as an add-on therapy for partial seizures in paediatric patients with previously drug-resistant seizures.     

Gabapentin Toxicity in Children Manifesting as Behavioral Changes

Summary: Pediatric experience with gabapentin (GBP), a new antiepileptic drug (AED), is limited. We describe 3 learning disabled children, 1 aged 7 years and 2 aged 10 years, with intractable partial seizures who developed severe behavioral problems while receiving modest doses of GBP. The children became hyperactive and had explosive outbursts consisting of aggressive and oppositional behavior. The behavioral problems were sufficiently severe to require discontinuation of GBP despite moderately improved seizure control.     

Concerns with Antiepileptic Drug Initiation: Safety, Tolerability, and Efficacy

Summary: A number of commonly used antiepileptic drugs (AEDs) produce severe adverse effects if they are introduced at their usual daily maintenance doses. Gradual slow titration of the dose often avoids these adverse effects almost entirely. Conversely, some AEDs can be started at their effective maintenance dose and perhaps even with a loading dose. Although the mechanisms of these distinctions among antiepileptic compounds are poorly understood, the phenomenon clearly has important implications for the optimal use of the drugs, especially when rapid seizure control is desired. Examples of drugs that require gradual introduction are lamotrigine, carbamazepine, topiramate, tiagabine, and zonisamide. Phenytoin, oxcarbazepine, gabapentin, valproate, and levetiracetam are examples of drugs that can be started at an effective dose.     

A Pilot Trial of Adjunctive Gabapentin in the Treatment of Bipolar Disorder

Several antiepileptic drugs (AEDs) have documented efficacy in the manic phase of bipolar disorder. To investigate the efficacy, tolerability, and safety of the new AED, gabapentin, in mania, we treated nine consecutive outpatients with bipolar I or II disorder by DSM-IV criteria who were experiencing hypomanic, manic, or mixed states inadequately responsive to standard mood stabilizers with open-label, adjunctive gabapentin. Response of manic symptoms was assessed monthly as none, minimal, moderate, or marked. Of the nine patients, seven displayed a moderate or marked reduction in manic symptoms by 1 month after addition of gabapentin, and an additional patient displayed moderate improvement after 3 months. Of these eight patients, six displayed continued antimanic responses for follow-up periods ranging from 1 to 7 months. Side effects were most commonly neurological, mild, and transient. Adjunctive gabapentin may have antimanic and mood-stabilizing effects in some patients with bipolar disorder and is generally well tolerated. Controlled studies of gabapentin in bipolar disorder appear to be warranted.     

Gabapentin versus lamotrigine monotherapy: a double-blind comparison in newly diagnosed epilepsy

PURPOSE: This randomised, double-blind study compared the newer antiepileptic drugs (AEDs) gabapentin (GBP) and lamotrigine (LTG) as monotherapy in newly diagnosed epilepsy. METHODS: Patients with partial seizures with and/or without secondary generalization or primary generalized tonic-clonic seizures were randomized to either GBP or LTG. During 2- and 6-week titration periods, respectively, GBP dosage reached 1,800 mg/day, and LTG, 150 mg/day. In the subsequent 24-week maintenance phase, the dose could be adjusted based on seizure control or adverse events between 1,200 and 3,600 mg/day for GBP and 100 and 300 mg/day for LTG. The primary end point was time to exit, a composite of efficacy and tolerability. Evaluable patients were used for the primary efficacy analysis, whereas tolerability was examined on an intent-to-treat basis. RESULTS: A total of 309 patients was randomized, and 291 (148 GBP, 143 LTG) were included in the evaluable population. Nineteen patients in each group had an exit event. The median time to exit was 69 days for GBP and 48 days for LTG. The hazard ratio was estimated as 1.043 (90% confidence intervals, 0.602-1.809). Overall, 106 (71.6% of the evaluable population) GBP-treated and 96 (67.1%) LTG-treated patients completed the study. Of those, 80 (75.5%) patients taking GBP and 73 (76.0%) taking LTG remained seizure free during the final 12 weeks of treatment. Only 14 (8.9%) GBP-treated patients and 15 (9.9%) LTG-treated patients withdrew because of study drug-related adverse events. CONCLUSIONS: GBP and LTG monotherapy were similarly effective and well tolerated in patients with newly diagnosed epilepsy.     

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。     

Behavioral Side Effects of Gabapentin in Children

Summary: We report 7 children who received gabapentin (GBP) as adjunctive medication and subsequently developed behavioral side effects. These behavioral changes consisted of intensification of baseline behaviors as well as new behavioral problems. Behaviors that parents considered most troublesome were tantrums, aggression directed toward others, hyperactivity, and defiance. All behavioral changes were reversible and were managed by dose reduction or discontinuation of GBP. All children had baseline attention deficit hyperactivity disorder and developmental delays.     

Gabapentin in PTSD: A Retrospective, Clinical Series of Adjunctive Therapy

Posttraumatic stress disorder (PTSD) symptoms may improve significantly with antidepressant medications, however some phenomena often remain refractory to the most commonly used treatments. Frequently, sleep disturbances, such as insomnia and nightmares, are symptoms of PTSD that are refractory to antidepressant treatment. Gabapentin, a novel anticonvulsant agent, has been of interest as a potential anxiolytic agent, but has not been evaluated in PTSD. We reviewed records of 30 consecutive patients who had been diagnosed with PTSD according to structured interviews and had received gabapentin as an adjunctive medication. For each patient, the target symptoms that led to the initiation of gabapentin treatment were identified. Using the most recent clinical data available, the change in target symptom severity following treatment was rated as unimproved, mildly improved, moderately improved, or markedly improved. The gabapentin was often first prescribed to facilitate sleep. The majority (77%) of patients showed moderate or greater improvement in duration of sleep, and most noted a decrease in the frequency of nightmares. The dose range was 300–3600 mg/day. Sedation and mild dizziness were the most commonly reported side effects. This retrospective study suggests that gabapentin may improve in particular sleep difficulties and also other symptoms associated with chronic PTSD. Prospective, controlled studies are needed to further investigate the effects of gabapentin on insomnia, nightmares, and other core PTSD symptoms.     

Safety of Topiramate: Adverse Events and Relationships to Dosing

Summary: To date, 1,809 individuals have been exposed to topiramate (TPM), primarily adults with partial-onset seizures. Of this total, 665 patients have been treated for more than 1 year, 177 for more than 3 years, and 67 for more than 5 years. The profile of treatment-emergent adverse reactions (TEAEs) observed with TPM at various dosages is based primarily on data from five double-blind, placebo-controlled trials in which 360 patients received TPM at target doses of 200–1,000 mg/day. Long-term safety is assessed on the basis of 1,001 patients treated with TPM in controlled and open trials for up to 5.3 years. Most of the commonly reported TEAEs were related to the central nervous system and were observed with greater frequency at dosages above the 200–600-mg/day range found to be optimal in dose ranging trials. Nephro-lithiasis not requiring surgery was seen in 1.5% of patients, and mild, dose-related weight loss was associated with TPM therapy. No clinically significant treatment-related abnormalities were observed in clinical laboratory parameters or in neurologic, electrocardiographic, oph-thalmologic, or audiologic tests.     

Gabapentin in painful HIV-related neuropathy: a report of 19 patients, preliminary observations

The objective of this study was to assess the efficacy and safety of Gabapentin as the sole analgesic in patients with HIV-related painful neuropathy. Nineteen patients with HIV-related painful neuropathy were administered Gabapentin. Efficacy was evaluated with two 100-mm Visual Analogue Scales (VAS) (0: no symptom; 100: worst symptom), rating pain and interference of pain with sleep, performed at baseline and monthly intervals. Main Pain VAS score decreased from a baseline of 55.7 +/- 19.1 mm to a final 14.7 +/- 18.6 mm (ANOVA P = 0.0001) and mean Sleep Interference VAS score decreased from a baseline of 60.4 +/- 31.9 mm to a final 15.5 +/- 27.7 mm (ANOVA P = 0.0001). Gabapentin provided significant pain relief in our patients with HIV-associated painful sensory neuropathy.     

Levetiracetam intravenous infusion as an alternative to oral dosing in patients with partial-onset seizures

PURPOSE: This multicenter, open-label study evaluated the short-term tolerability of intravenously (IV)-infused levetiracetam (LEV; 500-1,500 mg/100 ml, 15 min, b.i.d.) as a substitute for the same oral dose. METHODS: The study consisted of screening, 4-day IV LEV and 1-7 days of follow-up, and was conducted in 25 adults with partial-onset seizures receiving adjunctive oral LEV. RESULTS: During the 4-day IV LEV, 11 (44%) subjects experienced at least one treatment-emergent adverse event (TEAE), with headache and fatigue being the most frequently reported. Five (20%) subjects experienced TEAEs considered to be related to the study drug. The tolerability profile was consistent with that of oral LEV, with all events judged mild or moderate in severity, no discontinuations, and no serious AEs or deaths reported. No AE related to seizure worsening was reported during IV LEV or brief follow-up. CONCLUSIONS: LEV IV appears to be a well-tolerated, practical alternative in patients with partial-onset seizures temporarily unable to take the drug orally.     

Lamotrigine High-Dose Tolerability and Safety in Patients with Epilepsy: A Double-Blind, Placebo-Controlled, Eleven-Week Study

Summary: Purpose: This study was undertaken to evaluate the dose tolerability and safety of a chronic ascending twice-daily (b.i.d.) dosage regimen of 700 mg/day larnotrigine (LTG) and to include determination of the LTG pharmacokinetic profile at doses 500 mg/day in patients receiving concomitant enzyme-inducing antiepileptic drugs (AEDs). Methods: Twelve adult male epileptic patients treated with enzyme-inducing AEDs received 700 mg/day (b.i.d.) oral LTG (n = 8) or placebo (controls, n = 4). For 3 weeks, as outpatients they had their LTG dosage increased from 100 to 400 mg/day. Then, in a clinical research study unit, patients received regimens of 500, 600, and 700 mg/day for 1 week each. Controls received matching placebo in the same sequence. At study end, dosages were tapered in 2 weeks. Follow-up evaluations were made 7 days later. Results: Five LTG patients tolerated 700 mg/day for 1 week. LTG was reduced to 600 mg/day in a patient with mild diplopia and to 500 mg/day in a patient with mild oscillopsia and diplopia. One patient discontinued 300-mg/day therapy with a moderately intense diffuse papular skin rash, attributed to LTG. Headache, drowsiness, faintness, and diplopia, the common adverse events (AEs), were mild to moderate in intensity and occurred in 50–75% of patients in both groups (except for diplopia, occurring only with LTG). Concomitant AED plasma concentrations were not markedly changed by LTG. LTG pharmacokinetics were linear over the range of 500–700 mg/day. Conclusions: LTG doses 700 mg/day can be tolerated in patients receiving concomitant enzyme-inducing AEDs.     

Gabapentin versus vigabatrin as first add-on for patients with partial seizures that failed to respond to monotherapy: a randomized, double-blind, dose titration study. GREAT Study Investigators Group. Gabapentin in Refractory Epilepsy Add-on Treatment

PURPOSE: Our objective was to compare the efficacy and safety of gabapentin and vigabatrin as first-line add-on treatment in patients with partial epilepsy. METHODS: This was a multicenter, double-blind, randomized dose titration study. After baseline assessment and randomization, the dose could be increased if seizures persisted and reduced if side effects occurred. Health-related quality of life was assessed at baseline and at the end of the study. By a protocol amendment post hoc, all randomized patients were offered a standardized perimetry examination at the end of the study. Improvement rate was the proportion of patients with a reduction of seizure frequency of at least 50% during an 8-week period without any adverse events causing withdrawal. RESULTS: One hundred two patients were randomized and analyzed on an intent-to-treat basis. The improvement rate was 48% in the gabapentin group and 56% in the vigabatrin group. The improvement rate, when per protocol criteria were fulfilled, was 57% in the gabapentin group and 59% in the vigabatrin group. The proportion of seizure-free patients was 31% in the gabapentin group and 39% in the vigabatrin group. There was no difference in quality-of-life scores between the groups. Perimetry after termination of the study on 64 patients showed abnormal results in 3 of 32 patients in the vigabatrin group. CONCLUSION: Approximately one third of the patients in both groups became seizure-free. Although no major differences were seen in terms of the improvement rate between the groups, equivalence between the two drugs was not found.     

Sustained efficacy and long-term safety of oxcarbazepine: one-year open-label extension of a study in refractory partial epilepsy

PURPOSE: To evaluate the long-term efficacy, tolerability, and safety of oxcarbazepine (OXC) in medically refractory partial epilepsy. METHODS: This study is the open-label extension phase that followed a multicenter, randomized, double-blind, dose-response clinical study of OXC monotherapy in patients with medically refractory partial epilepsy. We analyzed the efficacy, tolerability, and safety of OXC during the first 48 weeks of open-label therapy. To evaluate efficacy, we compared the change in seizure frequency throughout the 48 weeks of treatment with OXC with the baseline seizure frequency that preceded the double-blind phase of the core study by an intent-to-treat and completer analysis. Safety and tolerability were evaluated by using an intent-to-treat analysis. RESULTS: Of the 87 patients enrolled in the double-blind study, 76 patients participated in the open-label extension phase. Fifty-five (72%) patients completed 48 weeks of open-label treatment on a median OXC dose of 2,400 mg/day. Based on an intent-to-treat analysis, the median reduction in seizure frequency was 47%(p = 0.0054); the 50 and 75% responder rates were 46.1 and 25.0%, respectively, with 6.6% of patients remaining seizure free. The completer analysis yielded comparable efficacy results. OXC was well tolerated, with 13% of patients exiting because of adverse events. The six most common adverse events, irrespective of their causal relation to OXC, were dizziness, headache, fatigue, diplopia, nausea, and rash. For the most part, these adverse events tended to be transient. CONCLUSIONS: The efficacy of OXC is sustained with good safety and tolerability profiles during long-term treatment of patients with medically refractory partial epilepsy.