Pregabalin add-on for drug-resistant focal epilepsy

Brivaracetam to Treat Partial Onset Seizures in Adults

Purpose of Review

Seizures are a hyperexcitable, and hypersynchronous imbalance between excitatory and inhibitory factors (E/I imbalance) in neurotransmission, and epilepsy is the recurrent manifestation of seizures within a reasonable time frame and without being attributable to a reversible cause. Brivaracetam is a derivative of the antiepileptic agent, levetiracetam, that is used as adjuvant therapy for focal onset seizures. It was approved by the FDA in 2016 and has shown promising results with minimal adverse effect reactions in clinical trials.

Recent Findings

Brivaracetam has been used in multiple clinical trials at various dosages in adults that have partial-onset seizures refractory to conventional treatment. A meta-analysis in 2016 showed that brivaracetam as adjunctive therapy was statically significant in its reduction of adults with drug-refractory seizure frequency.¹ The most commonly reported adverse effects that patients who were taking brivaracetam experienced were somnolence, headache, and dizziness. Further studies are necessary to conclude long term efficacy and safety profile of brivaracetam.

Conclusion

The treatment of epilepsy with pharmacologic agents is a difficult task due to balancing the efficacy of the drug with the side effect profile that will allow for the best quality of life for the patient. There are approximately 30 antiepileptic agents for clinicians to choose from. Brivaracetam is a novel antiepileptic agent that was approved for use by the FDA in 2016 and is showing promising results as monotherapy and adjunctive therapy in individuals with drug-refractory focal seizures while minimizing adverse drug reactions.

Genetic Knockout of TRPM2 Increases Neuronal Excitability of Hippocampal Neurons by Inhibiting Kv7 Channel in Epilepsy

Epilepsy is a chronic brain disease that makes serious cognitive and motor retardation. Ion channels affect the occurrence of epilepsy in various ways, but the mechanisms have not yet been fully elucidated. Transient receptor potential melastain2 (TRPM2) ion channel is a non-selective cationic channel that can permeate Ca²⁺ and critical for epilepsy. Here, TRPM2 gene knockout mice were used to generate a chronic kindling epilepsy model by PTZ administration in mice. We found that TRPM2 knockout mice were more susceptible to epilepsy than WT mice. Furthermore, the neuronal excitability in the hippocampal CA1 region of TRPM2 knockout mice was significantly increased. Compared with WT group, there were no significant differences in the input resistance and after hyperpolarization of CA1 neurons in TRPM2 knockout mice. Firing adaptation rate of hippocampal CA1 pyramidal neurons of TRPM2 knockout mice was lower than that of WT mice. We also found that activation of Kv7 channel by retigabine reduced the firing frequency of action potential in the hippocampal pyramidal neurons of TRPM2 knockout mice. However, inhibiting Kv7 channel increased the firing frequency of action potential in hippocampal pyramidal neurons of WT mice. The data suggest that activation of Kv7 channel can effectively reduce epileptic seizures in TRPM2 knockout mice. We conclude that genetic knockout of TRPM2 in hippocampal CA1 pyramidal neurons may increase neuronal excitability by inhibiting Kv7 channel, affecting the susceptibility to epilepsy. These findings may provide a potential therapeutic target for epilepsy.

Pregabalin for Recurrent Seizures in Critical Illness: A Promising Adjunctive Therapy, Especially for cyclic Seizures

BACKGROUND

Pregabalin (PGB) is an effective adjunctive treatment for focal epilepsy and acts by binding to the alpha2-delta subunit of voltage-gated calcium channels to reduce excitatory neurotransmitter release. Limited data exist on its use in the neurocritical care setting, including cyclic seizures-a pattern of recurrent seizures occurring at nearly regular intervals. Although the mechanism underpinning cyclic seizures remains elusive, spreading excitation linked to spreading depolarizations may play a role in seizure recurrence and periodicity. PGB has been shown to increase spreading depolarization threshold; hence, we hypothesized that the magnitude of antiseizure effect from PGB is more pronounced in patients with cyclic versus noncyclic seizures in a critically ill cohort with recurrent seizures.

METHODS

We conducted a retrospective case series of adults admitted to two academic neurointensive care units between January 2017 and March 2019 who received PGB for treatment of seizures. Data collected included demographics, etiology of brain injury, antiseizure medications, and outcome. Continuous electroencephalogram recordings 48 hours before and after PGB administration were reviewed by electroencephalographers blinded to the administration of antiseizure medications to obtain granular data on electrographic seizure burden. Cyclic seizures were determined quantitatively (i.e., < 50% variation of interseizure intervals for at least 50% of consecutive seizures). Coprimary outcomes were decrease in hourly seizure burden in minutes and decrease in seizure frequency in the 48 hours after PGB initiation. We used nonparametric tests for comparison of seizure frequency and burden and segmented linear regression to assess PGB effect.

RESULTS

We included 16 patients; the median age was 69 years, 11 (68.7%) were women, three (18.8%) had undergone a neurosurgical procedure, and five (31%) had underlying epilepsy. All seizures had focal onset; ten patients (62.5%) had cyclic seizures. The median hourly seizure burden over the 48 hours prior to PGB initiation was 1.87 min/hour (interquartile range 1.49-8.53), and the median seizure frequency was 1.96 seizures/hour (interquartile range 1.06-3.41). In the 48 hours following PGB (median daily dose 300 mg, range 75-300 mg), the median number of seizures per hour was reduced by 0.80 seizures/hour (95% confidence interval 0.19-1.40), whereas the median hourly seizure burden decreased by 1.71 min/hour (95% confidence interval 0.38-3.04). When we compared patients with cyclic versus noncyclic seizures, there was a relative decrease in hourly seizure frequency (- 86.7% versus - 2%, p = 0.04) and hourly seizure burden (- 89% versus - 7.8%, p = 0.03) at 48 hours.

CONCLUSIONS

PGB was associated with a relative reduction in seizure burden in neurocritically ill patients with recurrent seizures, especially those with cyclic seizures, and may be considered in the therapeutic arsenal for refractory seizures. Whether this effect is mediated via modulation of spreading depolarization requires further study.

Pregabalin add-on for drug-resistant focal epilepsy

BACKGROUND

This is an updated version of the Cochrane Review last published in Issue 7, 2019; it includes two additional studies. Epilepsy is a common neurological disease that affects approximately 1% of the UK population. Approximately one-third of these people continue to have seizures despite drug treatment. Pregabalin is one of the newer antiepileptic drugs that has been developed to improve outcomes. In this review we summarised the current evidence regarding pregabalin when used as an add-on treatment for drug-resistant focal epilepsy.

OBJECTIVES

To assess the efficacy and tolerability of pregabalin when used as an add-on treatment for drug-resistant focal epilepsy.

SEARCH METHODS

For the latest update we searched the following databases on 16 November 2020: Cochrane Register of Studies (CRS Web), and MEDLINE (Ovid, 1946 to 16 November 2020). CRS Web includes randomised or quasi-randomised, controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organisation International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialised Registers of Cochrane Review Groups, including Epilepsy. We imposed no language restrictions. We contacted the manufacturers of pregabalin and authors in the field to identify any relevant unpublished studies.

SELECTION CRITERIA

We included randomised controlled trials comparing pregabalin with placebo or an alternative antiepileptic drug as an add-on for people of any age with drug-resistant focal epilepsy. Double-blind and single-blind trials were eligible for inclusion. The primary outcome was 50% or greater reduction in seizure frequency; secondary outcomes were seizure freedom, treatment withdrawal for any reason, treatment withdrawal due to adverse effects, and proportion of individuals experiencing adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and extracted the relevant data. Primary analyses were intention-to-treat (ITT). We presented summary risk ratios (RRs) and odds ratios (ORs) with 95% confidence intervals (CIs). We evaluated dose response in regression models. We carried out a risk of bias assessment for each included study using the Cochrane risk of bias tool and assessed the overall certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 11 randomised controlled trials (3949 participants). Nine trials compared pregabalin to placebo. For the primary outcome, participants randomised to pregabalin were significantly more likely to attain a 50% or greater reduction in seizure frequency compared to placebo (RR 1.95, 95% CI 1.40 to 2.72, 9 trials, 2663 participants, low-certainty evidence). The odds of response doubled with an increase in dose from 300 mg/day to 600 mg/day (OR 1.99, 95% CI 1.74 to 2.28), indicating a dose-response relationship. Pregabalin was significantly associated with seizure freedom (RR 3.94, 95% CI 1.50 to 10.37, 4 trials, 1125 participants, moderate-certainty evidence). Participants were significantly more likely to withdraw from pregabalin treatment than placebo for any reason (RR 1.33, 95% CI 1.10 to 1.60; 9 trials, 2663 participants; moderate-certainty evidence) and for adverse effects (RR 2.60, 95% CI 1.86 to 3.64; 9 trials, 2663 participants; moderate-certainty evidence). Three trials compared pregabalin to three active-control drugs: lamotrigine, eventrate and gabapentin. Participants allocated to pregabalin were significantly more likely to achieve a 50% or greater reduction in seizure frequency than those allocated to lamotrigine (RR 1.47, 95% CI 1.03 to 2.12; 1 trial, 293 participants) but not those allocated to eventrate (RR 0.94, 95% CI 0.80 to 1.11; 1 trial, 509 participants) or gabapentin (RR 0.96, 95% CI 0.82 to 1.12; 1 trial, 484 participants). We found no significant differences between pregabalin and lamotrigine for seizure freedom (RR 1.39, 95% CI 0.40 to 4.83). However, significantly fewer participants achieved seizure freedom with add-on pregabalin compared to eventrate (RR 0.50, 95% CI 0.30 to 0.85). No data were reported for this outcome for pregabalin versus gabapentin. We detected no significant differences in treatment withdrawal rate for any reason or due to adverse effects, specifically, during either pooled analysis or subgroup analysis. Ataxia, dizziness, somnolence, weight gain, headache and fatigue were significantly associated with pregabalin than in active control. We rated the overall risk of bias in the included studies as low or unclear due to the possibility of publication bias and lack of methodological details provided. We assessed all the studies to be at a high risk of funding bias as they were all sponsored by Pfizer. We rated the certainty of the evidence as very low to moderate using the GRADE approach.

AUTHORS' CONCLUSIONS

For people with drug-resistant focal epilepsy, pregabalin when used as an add-on treatment was significantly more effective than placebo at producing a 50% or greater seizure reduction and seizure freedom. Results demonstrated efficacy for doses from 150 mg/day to 600 mg/day, with increasing effectiveness at 600 mg doses, although there were issues with tolerability at higher doses. However, the trials included in this review were of short duration, and longer-term trials are needed to inform clinical decision-making. This review focused on the use of pregabalin in drug-resistant focal epilepsy, and the results cannot be generalised to add-on treatment for generalised epilepsies. Likewise, no inference can be made about the effects of pregabalin when used as monotherapy.

Antiepileptic medicines in men and women with stroke in Sweden, a registry-based study

BACKGROUND AND AIM

To describe the utilization of the first antiepileptic drug (AED) in men and women with previous stroke in a nationwide population.

METHODS

Prescription data, patient's age, and sex were collected from the Swedish Drug Register and cross-linked to diagnosis data from the National Patient Register and data from Statistics Sweden. Patients with a first dispensation of an AED after stroke between 1 January 2007 and 31 December 2014 were included.

RESULTS

A total of 10 958 patients with stroke were initiated on AED treatment (51% women, mean age 75 years). Gabapentin (n = 3073, 28%), pregabalin (n = 2476, 22%), carbamazepine (n = 2330, 21%), levetiracetam (n = 1158, 10%), and valproic acid (n = 833, 7%) were the most dispensed AEDs. After stratification by the presence of a neuropathic pain diagnosis, gabapentin, and pregabalin were the most used AEDs. In contrast, after stratification for epilepsy/convulsions diagnosis, carbamazepine and levetiracetam were the most initiated AEDs.

CONCLUSION

This study suggests that AED is mainly used for neuropathic/poststroke pain and the study shows gabapentin and pregabalin to be the most used AEDs. For epilepsy, carbamazepine and levetiracetam were the most used AEDs in patients with previous stroke.

Pregabalin as adjunctive therapy in adult and pediatric patients with generalized tonic-clonic seizures: A randomized, placebo-controlled trial

OBJECTIVE

Generalized tonic-clonic (GTC) seizures are the most common type of generalized seizure and more common in children than adults. This phase 3 study evaluated the efficacy and safety of pregabalin for GTC seizures in adults and children with epilepsy.

METHODS

This randomized, double-blind, multicenter study evaluated pregabalin (5 mg/kg/day or 10 mg/kg/day) vs placebo as adjunctive therapy for 10 weeks (following a 2-week dose escalation), in pediatric and adult patients (aged 5-65 years) with GTC seizures. Primary endpoint was change in log-transformed 28-day seizure rate during active treatment. Secondary endpoints included responder rates, defined as proportion of patients with ≥50% reduction in 28-day GTC seizure rate from baseline. Safety was monitored throughout.

RESULTS

Of 219 patients, 75, 72, and 72 were randomized to adjunctive pregabalin 5 mg/kg/day, 10 mg/kg/day, and placebo, respectively. Fifteen, 11, and 6 patients discontinued from the 5 mg/kg/day, 10 mg/kg/day, and placebo arms, respectively, most commonly due to adverse events (AEs; 10.7%, 6.9%, and 5.6%, respectively). A nonsignificant change in log-transformed mean 28-day seizure rate was seen with pregabalin 10 mg/kg/day vs placebo (least-squares [LS] mean difference -0.01 [95% confidence interval (CI) -0.19 to 0.16]; P = .8889) and with pregabalin 5 mg/kg/day vs placebo (LS mean difference 0.02 [CI -0.15 to 0.19]; P = .8121). Similar observations were noted for adults and children. No significant differences were seen for secondary endpoints with pregabalin vs placebo, including responder rate. The most common AEs (≥10%) were dizziness, headache, and somnolence. Most were of mild/moderate intensity. Seven patients had serious AEs, with one death in the placebo arm (sudden unexpected death in epilepsy).

SIGNIFICANCE

Adjunctive pregabalin treatment did not change GTC seizure rate in adults or children. The safety profile of pregabalin was similar to that known; treatment was well tolerated with few discontinuations due to AEs.