Gabapentin add-on treatment for drug-resistant focal epilepsy

Lamotrigine add-on therapy for drug-resistant focal epilepsy

BACKGROUND

This is an updated version of a Cochrane Review last updated in 2020. Epilepsy is a common neurological disorder, affecting 0.5% to 1% of the population. In nearly 30% of cases, epilepsy is resistant to currently available drugs. Pharmacological treatment remains the first choice to control epilepsy. Lamotrigine is a second-generation antiseizure medication. When used as an add-on (in combination with other antiseizure medications), lamotrigine can reduce seizures, but with some adverse effects.

OBJECTIVES

To evaluate the benefits and harms of add-on lamotrigine, compared with add-on placebo or no add-on treatment in people with drug-resistant focal epilepsy.

SEARCH METHODS

For this update, we searched the Cochrane Register of Studies (CRS Web) and MEDLINE (Ovid) on 3 October 2022 with no language restrictions. CRS Web includes randomised and quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialised Registers of Cochrane Review Groups, including Epilepsy.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that investigated add-on lamotrigine versus add-on placebo or no add-on treatment in people of any age with drug-resistant focal epilepsy. We used data from the first period of eligible cross-over trials.

DATA COLLECTION AND ANALYSIS

For this update, two review authors independently selected trials and extracted data. Our primary outcome was 50% or greater reduction in seizure frequency. Our secondary outcomes were treatment withdrawal, adverse effects, cognitive effects, and quality of life. Primary analyses were by intention-to-treat. We performed sensitivity best- and worse-case analyses to account for missing outcome data. We calculated pooled risk ratios (RRs) with 95% confidence intervals (95% Cls) for dichotomous outcomes.

MAIN RESULTS

We identified no new studies for this update, so the results and conclusions of the review are unchanged. We included five parallel-group studies in adults or children, eight cross-over studies in adults or children, and one parallel study with a responder-enriched design in infants. In total, these 14 studies enroled 1806 eligible participants (38 infants, 199 children, 1569 adults). Baseline phases ranged from four to 12 weeks and treatment phases ranged from eight to 36 weeks. We rated 11 studies (1243 participants) at low overall risk of bias and three (697 participants) at unclear overall risk of bias due to lack of information on study design. Four studies (563 participants) reported effective blinding. Lamotrigine compared with placebo probably increases the likelihood of achieving 50% or greater reduction in seizure frequency (RR 1.80, 95% CI 1.45 to 2.23; 12 trials, 1322 participants (adults and children); moderate-certainty evidence). There is probably little or no difference in risk of treatment withdrawal for any reason among people treated with lamotrigine versus people treated with placebo (RR 1.11, 95% CI 0.91 to 1.37; 14 trials; 1806 participants; moderate-certainty evidence). Lamotrigine compared with placebo is probably associated with a greater risk of ataxia (RR 3.34, 99% Cl 2.01 to 5.55; 12 trials; 1525 participants; moderate-certainty evidence), dizziness (RR 1.76, 99% Cl 1.28 to 2.43; 13 trials; 1768 participants; moderate-certainty evidence), nausea (RR 1.81, 99% CI 1.22 to 2.68; 12 studies, 1486 participants; moderate-certainty evidence), and diplopia (RR 3.79, 99% Cl 2.15 to 6.68; 3 trials, 944 participants; moderate-certainty evidence). There is probably little or no difference in the risk of fatigue between lamotrigine and placebo (RR 0.82, 99% CI 0.55 to 1.22; 12 studies, 1552 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Lamotrigine as an add-on treatment for drug-resistant focal seizures is probably effective for reducing seizure frequency. Certain adverse effects (ataxia, dizziness, diplopia, and nausea) are probably more likely to occur with lamotrigine compared with placebo. There is probably little or no difference in the number of people who withdraw from treatment with lamotrigine versus placebo. The trials were of relatively short duration and provided no long-term evidence. In addition, some trials had few participants. Further trials are needed to assess the long-term effects of lamotrigine and to compare lamotrigine with other add-on drugs.

Gabapentinoids: a therapeutic review

The Australian Therapeutic Goods Administration's approved indications for prescription of gabapentinoids are refractory focal epilepsy and neuropathic pain. Use of gabapentinoids outside of the approved indications is common, but evidence for this is limited, especially for chronic nonspecific back pain and nonradicular leg pain. Some effects of gabapentinoids encourage their nonmedical use (e.g. euphoria, sedation, disinhibition). Widespread nonmedical use has increased the incidence of accidental and deliberate poisonings. Dependence may develop with chronic use of gabapentinoids and abrupt cessation may induce withdrawal symptoms. If the indication for continued use is unclear, gradual dose tapering as a means of deprescribing is recommended. Clinicians should consider the indication, patient characteristics and harm-benefit profile when prescribing gabapentinoids. Some people, such as those with kidney disease, have an increased risk of harm when using these drugs.

Gabapentin monotherapy for epilepsy: A review

BACKGROUND

Epilepsy is one of the most common chronic neurological disorders, affecting more than 50 million people globally. In this review we summarised the evidence from randomised controlled trials of gabapentin used as monotherapy for the treatment of focal epilepsy, both newly diagnosed and drug-resistant, with or without secondary generalisation.

OBJECTIVE

To assess the effects of gabapentin monotherapy for people with epileptic focal seizures with and without secondary generalisation.

METHODS

We searched the Cochrane Register of Studies (CRS Web) and MEDLINE (Ovid, 1946 to 24 February 2020) on 25 February 2020. CRS Web includes randomised or quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, the Cochrane Central Register of Controlled Trials (CENTRA), and the specialised registers of Cochrane Review Groups including the Cochrane Epilepsy Group. We also searched several Russian databases, reference lists of relevant studies, ongoing trials registers, conference proceedings, and we contacted trial authors.

RESULTS

We found five randomised controlled trials (3167 participants) comparing gabapentin to other antiepileptic drugs (AEDs) and differing doses of gabapentin as monotherapy for newly diagnosed focal epilepsy and drug- resistant focal epilepsy with or without secondary generalisation. Two review authors independently applied the inclusion criteria, assessed trial quality, risk of bias, and extracted data. We used the GRADE approach to assess the certainty of evidence and present seven patient-important outcomes in the "Summary of findings" tables. The quality of evidence was very low to moderate due to poor reporting quality, poor trial design, and other risks of bias, such as selective presentation of findings and potential heavy industry input. Better quality research may change our certainty in the effect estimates. None of the included trials reported on the number of people with 50% or greater reduction in seizures and time to withdrawal (retention time) in an extractable way. Gabapentin-treated participants were more likely to withdraw from treatment for any cause (285/539) than those treated with lamotrigine, oxcarbazepine, or topiramate pooled together (695/1317) (RR 1.13, 95% CI 1.02 to 1.25; 3 studies, 1856 participants; moderate-certainty evidence), but not carbamazepine. Fewer people treated with gabapentin withdrew from treatment owing to adverse events (190/525) than those treated with carbamazepine, oxcarbazepine, or topiramate (479/1238), (RR 0.79, 95% CI 0.69 to 0.91; 1763 participants, 3 studies; moderate-certainty evidence), but not lamotrigine.

CONCLUSION

Gabapentin as monotherapy probably controlled seizures no better and no worse than comparator AEDs (lamotrigine, carbamazepine, oxcarbazepine, and topiramate). Compared to carbamazepine, gabapentin was probably better in retaining people in studies and preventing withdrawals due to adverse events. The most common side effects associated with gabapentin were ataxia (poor co-ordination and unsteady gait), dizziness, fatigue, and drowsiness.

Drug repositioning for idiopathic epilepsy using gene expression signature data

Epilepsy is one of the most common neurological disorders, affecting millions of patients with a substantial economic and human burden. About 30-40% of epileptic patients remain un-treated after the therapeutic option. Genetic or idiopathic epilepsy count about 40% of total epilepsy patients, showing a maximum percentage for drug-resistant epilepsy. Since the last century basic approach to understanding disease progression and drug discovery has been through the prism, exploring all possible causes and treatment options. Here we report about the gene expression-based drug repositioning study for epilepsy. Epilepsy gene expression data was retrieved from the Gene Expression Omnibus database, while drugs-associated gene expression data was retrieved from the Connectivity map (CMAP). The study predicted309 drug compounds which can alter genetic epilepsy-mediated gene signature using an in-house developed R-script. These compounds were docked against identified epilepsy targets- Voltage-gated sodium channel subunit α2 (Nav1.2); GABA receptor α1-β1; and Voltage-gated calcium channel α1G (Cav3.1)using Carbamazepine, Clonazepam, and Pregabalin as standard drugs, respectively. Twenty-one predicted drug compounds showed better binding affinity than respective standards against the selected epileptic receptors. Among these drug compounds, Ergocalciferol, Oxaprozin, Flunarizine, Triprolidine and Cyproheptadine have been previously reported for anti-epileptic activities and can be potential hits to target idiopathic epilepsy.