Tiagabine add-on for drug-resistant partial epilepsy

Tiagabine add-on therapy for drug-resistant focal epilepsy

BACKGROUND

Epilepsy is a common neurological condition that affects up to 1% of the population. Nearly 30% of people with epilepsy are resistant to currently available antiepileptic drugs (AEDs) and require treatment with multiple antiepileptic drugs in combination. Tiagabine is one of the newer AEDs that can be used as an adjunct (add-on) to standard AEDs.

OBJECTIVES

To evaluate the efficacy and tolerability of tiagabine when used as an add-on treatment for people with drug-resistant focal seizures.

SEARCH METHODS

This is an updated Cochrane review, last published in 2014. For the latest update, we searched the following databases on 22 January 2019: Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group's Specialized Register and the Cochrane Central Register of Controlled Trials, MEDLINE (Ovid, 1946 to January 21, 2019), ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform. We imposed no language restrictions. We also contacted the manufacturers of tiagabine and experts in the field to identify any ongoing or unpublished studies.

SELECTION CRITERIA

We included randomised placebo-controlled add-on trials conducted in people of any age with focal epilepsy. The studies could be double-, single-, or unblinded and of parallel or cross-over design. They had to have a minimum treatment period of eight weeks. We also included trials using an active drug control group.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and extracted data according to the standard methodological procedures expected by the Cochrane Collaboration for this review update. We resolved disagreements by discussion. Outcomes investigated included 50% or greater reduction in seizure frequency, treatment withdrawal, adverse effects, effects on cognition and quality of life. The primary analyses were performed by intention-to-treat. We calculated worst-case and best-case analyses for seizure outcomes. We evaluated dose response using regression models. Two review authors assessed risk of bias in each study using the Cochrane 'Risk of bias' tool.

MAIN RESULTS

No further studies were added since the previous update in 2014. The review included six trials (four parallel-group and two cross-over group trials) consisting of 948 participants. For the main comparison, tiagabine versus placebo, all participants were aged between 12 and 77 years and the study treatment periods ranged from 12 to 22 weeks. The overall risk ratio (RR) with 95% confidence intervals (CIs) for a 50% or greater reduction in seizure frequency (tiagabine versus placebo) was 3.16 (95% CI 1.97 to 5.07; 3 trials; 769 participants; high-certainty evidence). Because of differences in response rates among trials, regression models were unable to provide reliable estimates of response to individual doses. The RR for treatment withdrawal (tiagabine versus placebo) was 1.81 (95% CI 1.25 to 2.62; 3 trials, 769 participants; moderate-certainty evidence). Dizziness and tremor were significantly associated with tiagabine therapy. For cognitive and quality-of-life outcomes, the limited available data suggested no significant effects on cognition, mood, or adjustment. One trial comparing tiagabine with an active drug control group (tiagabine versus topiramate) found no significant differences between the two add-on drugs for a 50% or greater reduction in seizure frequency (RR 0.54, 95% CI 0.19 to 1.58; 1 trial; 41 participants) or for treatment withdrawal (RR 1.43, 95% CI 0.74 to 2.74; one trial; 41 participants). We judged two of the six included studies to have low risk of bias, three studies to have an unclear risk of bias, and one study to have a high risk of bias. Methods for randomisation sequence generation were the least reported trial design factor and generated the most concerns regarding risk of bias. We rated the overall certainty of the evidence as largely moderate to high using the GRADE approach. We rated the evidence for two of the adverse effect outcomes, nausea and tremor, as low certainty.

AUTHORS' CONCLUSIONS

Tiagabine reduced seizure frequency but was associated with some adverse effects when used as an add-on treatment in people with drug-resistant focal epilepsy. The findings of the current review are mainly applicable to adults and adolescents, and may not necessarily be applicable to children as none of the trials included participants aged under 12 years. We found no significant differences between tiagabine and topiramate as add-on drugs; however, evidence was provided by a single trial and was therefore limited.

Pharmacotherapy for Seizures in Neonates with Hypoxic Ischemic Encephalopathy

Seizures are common in neonates with moderate and severe hypoxic ischemic encephalopathy (HIE) and are associated with worse outcomes, independent of HIE severity. In contrast to adults and older children, no new drugs have been licensed for treatment of neonatal seizures over the last 50 years, because of a lack of controlled clinical trials. Hence, many antiseizure medications licensed in older children and adults are used off-label for neonatal seizure, which is associated with potential risks of adverse effects during a period when the brain is particularly vulnerable. Phenobarbital is worldwide the first-line drug and is considered standard of care, although there is a limited evidence base for its efficacy. Second-line agents include phenytoin, benzodiazepines, levetiracetam, and lidocaine. These drugs are discussed in more detail along with two emerging drugs (bumetanide and topiramate). More safety, pharmacokinetic, and efficacy data are needed from well-designed clinical trials to develop safe and effective antiseizure regimes for the treatment of neonatal seizures in HIE.

Network meta-analyses of antiepileptic drug efficacy and tolerability in drug-resistant focal epilepsies: a clinical perspective

PURPOSE

Network meta-analysis (NMA) is a new technique that allows multiple treatment comparisons and provides estimates of effect sizes for all possible pair-wise comparisons. Several NMAs of antiepileptic drug (AED) efficacy and tolerability in individuals with refractory focal epilepsy, however, came to non-specific and, in some cases, divergent conclusions. We review some clinical factors that may be responsible for these inconsistent findings.

RESULTS

A major issue is the small number of individuals included in the meta-analyses with consequent wide confidence intervals and lack of ability to achieve significant results. Further issues are lack of robustness of the measured efficacy outcome-the responder ratio (the percentage of individuals with a >50 % improvement in seizure frequency); the selection of randomized studies (RCTs) included, i.e., the inclusion of studies with heterogeneous populations (children and adults); and inclusion of people treated with different doses of the experimental drug. Some methods of analysing data from RCTs, such as the last observation carried forward (LOCF) analysis, the choice of different phases of the study to compare to baseline, and the year in which the trial was conducted, selectively affect measurement of efficacy outcomes. Titration speed and other methodological aspects selectively affect tolerability.

CONCLUSION

Several factors restrict the analysis of clinically useful estimates of the comparative efficacy of AEDs, while analysis of tolerability may be easier to accomplish.

Tiagabine add-on for drug-resistant partial epilepsy

BACKGROUND

Epilepsy is a common neurological condition that affects almost 0.5% to 1% of the population. Nearly 30% of people with epilepsy are resistant to currently available drugs. Tiagabine is one of the newer antiepileptic drugs; its effects as an adjunct (add-on) to standard drugs are assessed in this review.

OBJECTIVES

To evaluate the effects of add-on treatment with tiagabine on seizures, adverse effects, cognition and quality of life for people with drug-resistant localisation-related seizures.

SEARCH METHODS

This is an updated version of the original Cochrane review published in 2012 (Issue 5). We searched the Cochrane Epilepsy Group Specialised Register (November 2013), the Cochrane Central Register of Controlled Trials (CENTRAL, 2013, Issue 10) and MEDLINE (1946 to November 2013). No language restrictions were imposed. We also contacted the manufacturers of tiagabine and experts in the field to seek any ongoing or unpublished studies.

SELECTION CRITERIA

Randomised placebo-controlled add-on trials of people of any age with localisation-related seizures in which an adequate method of concealment of randomisation was used were included. The studies could be double-blind, single-blind or unblinded and of parallel or cross-over design. They had to have a minimum treatment period of eight weeks. Trials using an active drug control group were also included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and extracted data. Disagreements were resolved by discussion. Outcomes investigated included 50% or greater reduction in seizure frequency, treatment withdrawal, adverse effects, effects on cognition and quality of life. The primary analyses were performed by intention-to-treat. Worst-case and best-case analyses were calculated for seizure outcomes. Dose response was evaluated in regression models. Risk of bias in each study was assessed by two review authors using the Cochrane 'Risk of bias' tool.

MAIN RESULTS

Four parallel-group and two cross-over group trials were included. The overall risk ratio (RR) with 95% confidence intervals (CIs) for a 50% or greater reduction in seizure frequency (tiagabine vs placebo) was 3.16 (95% CI 1.97 to 5.07). Because of differences in response rates among trials, regression models were unable to provide reliable estimates of response to individual doses. The RR for treatment withdrawal was 1.81 (95% CI 1.25 to 2.62). The 99% CIs for the adverse effects of dizziness, fatigue, nervousness and tremor did not include unity, indicating that they are significantly associated with tiagabine. For cognitive and quality of life outcomes, the limited available data suggested no significant effects on cognition and mood and adjustment. Two of the five studies were judged as having low risk of bias, three studies unclear risk of bias and one study high risk of bias. Overall study quality was rated as high using the GRADE approach.

AUTHORS' CONCLUSIONS

Tiagabine reduces seizure frequency but is associated with some adverse effects when used as an add-on treatment for people with drug-resistant localisation-related seizures.

Perampanel: What is its Place in the Management of Partial Onset Epilepsy?

Introduction

Current pathways for treatment of partial onset epilepsy are diverse and include 14 new antiepileptic drugs (AEDs) licensed for use as either monotherapy or adjunctive therapy. However, the impact of these new AEDs on the treatment of partial epilepsy has so far been disappointing and there persists a need for additional drugs. Recently, perampanel, a first-in-class AED was licensed as an adjunct for the management of refractory partial onset seizures with or without secondary generalization in patients 12 years and older. This review highlights the current management of partial epilepsy and analyses the published clinical and preclinical data of perampanel to consider its potential role in the treatment of partial epilepsy.

Methods

A literature review of Embase, Medline and PubMed was conducted in April 2013 using the search terms ‘perampanel’ and ‘AMPA receptor antagonist/blocker’. Publications were included if they discussed perampanel in the context of preclinical or clinical epilepsy.

Results

Perampanel acts on the glutamate pathway. It is a novel highly selective non-competitive alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist. This is a previously untargeted post-synaptic glutamate receptor. It is responsible for mediating rapid trans-synaptic signal transduction and hence believed to play a major role in seizure propagation. The three pivotal placebo-controlled trials of adjunctive perampanel demonstrated that the effective dosing range is 4–12 mg/day. The drug can be prescribed once daily, and its adverse effect profile is minimal with dizziness, fatigue, headache, and somnolence being the most commonly reported.

Conclusions

Perampanel is a welcome addition as it represents an alternative approach in the management of epilepsy with potential to have a significant impact on the prognosis of intractable epilepsy. However, it has only recently been licensed for clinical use in Europe, the USA, and Canada, and there are no data directly comparing it with other AEDs; hence, it remains far too early to ascertain its place in the treatment of patients with partial epilepsy.

Tiagabine in clinical practice: effects on seizure control and behavior

OBJECTIVE

Preapproval randomized controlled trials of antiepileptic drugs provide data in limited patient groups. We assessed the side effect and seizure reduction profile of tiagabine (TGB) in typical clinical practice.

METHODS

Investigators recorded adverse effect (AE), seizure, and assessment-of-benefit data prospectively in sequential patients treated open label with TGB.

RESULTS

Two hundred ninety-two patients (39 children) were enrolled to be treated long term with TGB. Seizure types were focal-onset (86%), generalized-onset (12%), both focal- and generalized-onset (0.3%), and multiple associated with Lennox-Gastaut Syndrome (2%). Two hundred thirty-one received at least one dose of TGB (median = 28 mg/day) and had follow-up seizure or AE data reported. Common AEs were fatigue, dizziness, psychomotor slowing, ataxia, gastrointestinal upset, weight change, insomnia, and "others" (mostly behavioral). Serious AEs occurred in 19 patients: behavioral effects (n = 12), status epilepticus (n = 3), others (n = 3), and sudden unexplained death (n = 1). No patients experienced suicidal ideation/behavior, rash, nephrolithiasis, or organ failure. Seizure outcomes were seizure freedom (5%), ≥75% reduction (12%), ≥50% reduction (23%), and increased number of seizures (17%), or new seizure type (1%).

CONCLUSIONS

Behavioral AEs occurred in a larger proportion of patients compared to those reported in TGB preapproval randomized controlled trials. A moderate percentage of patients had a meaningful reduction in seizure frequency. In clinical practice, TGB remains a useful antiepileptic drug.