Dose-response trial of pregabalin adjunctive therapy in patients with partial seizures

Factors associated with placebo response rate in randomized controlled trials of antiseizure medications for focal epilepsy

OBJECTIVE

Randomized controlled trials (RCTs) are necessary to evaluate the efficacy of novel treatments for epilepsy. However, there have been concerning increases in the placebo responder rate over time. To understand these trends, we evaluated features associated with increased placebo responder rate.

METHODS

Using individual-level data from 20 focal-onset seizure trials provided by seven pharmaceutical companies, we evaluated associations with change in seizure frequency in participants randomized to placebo. We used multivariable logistic regression to evaluate participant and study factors associated with differing rates of 50% reduction in seizure frequency during blinded placebo treatment, as compared to pre-randomization baseline seizure frequency. In addition, we focused on the association of placebo responder rate with pre-randomization baseline seizure frequency and country of recruitment.

RESULTS

In the pooled analysis of 1674 participants randomized to placebo, a higher 50% responder rate (50RR) was associated with a shorter duration of epilepsy (p = .006), lower baseline seizure rate (p = .002), fewer concomitant antiseizure medications (p = .004), absence of adverse events (p < .001), more trial arms (p = .006), and geographic region (p < .001). Mixture modeling indicated a significantly higher 50RR in Bulgaria, Croatia, India, and Canada (42% in the higher group vs 22% in the lower group comprising all 40 other countries, p < 10-15). In addition, there was a significantly higher 50RR in participants with a baseline seizure frequency of six or fewer seizures per 28 days (29% vs 21%, p = .00018).

SIGNIFICANCE

These results can assist future RCTs in estimating the expected placebo responder rate, which may lead to more reliable power estimates. Higher placebo responder rate was associated with markers of less-refractory epilepsy. There were concerning significant differences in placebo responder rate by country and geographic region as well as an elevated placebo responder rate in participants with baseline seizure frequency close to the minimum eligibility criteria.

Efficacy and safety of add-on antiseizure medications for focal epilepsy: A network meta-analysis

OBJECTIVE

Several antiseizure medications (ASMs) have been approved for the treatment of focal epilepsy. However, there is a paucity of evidence on direct comparison of ASMs. We evaluated the comparative efficacy and safety of all approved add-on ASMs for the treatment of focal epilepsy using network meta-analysis.

METHODS

Data through extensive literature search was retrieved from PubMed, Embase, Cochrane, and ClinicalTrial.gov databases using predefined search terms from inception through March 2023. PRISMA reporting guidelines (CRD42023403450) were followed in this study. Efficacy outcomes assessed were ≥50%, ≥75%, and 100% responder rates. Patient retention rate and safety outcomes such as overall treatment-emergent adverse events (TEAEs) and individual TEAEs were assessed. "Gemtc" 4.0.4 package was used to perform Bayesian analysis. Outcomes are reported as relative risks (RRs) and 95% confidence interval (CI).

RESULTS

Literature search retrieved 5807 studies of which, 75 studies were included in the analysis. All ASMs showed significantly higher ≥50% responder rate compared with placebo. Except the ≥75% seizure frequency reduction for zonisamide (2.23; 95% CI: 1.00-5.70) and 100% for rufinamide (2.03; 95% CI: 0.54-11.00), all other interventions showed significantly higher ≥75% and 100% responder rates compared with placebo. Among treatments, significantly higher 100% responder rate was observed with cenobamate compared to eslicarbazepine (10.71; 95% CI: 1.56-323.9) and zonisamide (10.63; 95% CI: 1.37-261.2). All ASMs showed a lower patient retention rate compared to placebo, with the least significant value observed for oxcarbazepine (0.77; 95% CI: 0.7-0.84). Levetiracetam showed a lower risk of incidence (1.0; 95%CI: 0.94-1.1; SUCRA: 0.885067) for overall TEAE compared with other medications.

SIGNIFICANCE

All approved ASMs were effective as add-on treatment for focal epilepsy. Of the ASMs included, cenobamate had the greatest likelihood of allowing patients to attain seizure freedom.

PLAIN LANGUAGE SUMMARY

This article compares the efficacy and safety of antiseizure medications (ASMs) currently available to neurologists in the treatment of epileptic patients. Several newer generation ASMs that have been developed may be as effective or better than the older medications. We included 75 studies in the analysis. In comparison, all drugs improved ≥50%, ≥75% and 100% responder rates compared to control, except for Zonisamide and Rufinamide in the ≥75% and 100% responder rate categories. Retention of patients undergoing treatment was lower in drugs than placebo. All drugs were tolerated, the levetiracetam showed the best tolerability. Cenobamate more likely help completely to reduce seizures.

Antiobesity pharmacotherapy to facilitate living kidney donation

Obesity is a chronic, relapsing disease that increases the risks of living kidney donation; at the same time, transplant centers have liberalized body mass index constraints for donors. With the increasing number of antiobesity medications available, the treatment of obesity with antiobesity medications may increase the pool of potential donors and enhance donor safety. Antiobesity medications are intended for long-term use given the chronic nature of obesity. Cessation of treatment can be expected to lead to weight regain and increase the risk of comorbidity rebound/development. In addition, antiobesity medications are meant to be used in conjunction with-rather than in replacement of-diet and physical activity optimization. Antiobesity medication management includes selecting medications that may ameliorate any coexisting medical conditions, avoiding those that are contraindicated in such conditions, and being sensitive to any out-of-pocket expenses that may be incurred by the potential donor. A number of questions remain regarding who will and should shoulder the costs of long-term obesity treatment for donors. In addition, future studies are needed to quantify the degree of weight loss and duration of weight loss maintenance needed to normalize the risk of adverse kidney outcomes relative to comparable nondonors and lower-weight donors.

Holistic Treatment Response: An International Expert Panel Definition and Criteria for a New Paradigm in the Assessment of Clinical Outcomes of Spinal Cord Stimulation

BACKGROUND

Treatment response to spinal cord stimulation (SCS) is focused on the magnitude of effects on pain intensity. However, chronic pain is a multidimensional condition that may affect individuals in different ways and as such it seems reductionist to evaluate treatment response based solely on a unidimensional measure such as pain intensity.

AIM

The aim of this article is to add to a framework started by IMMPACT for assessing the wider health impact of treatment with SCS for people with chronic pain, a "holistic treatment response".

DISCUSSION

Several aspects need consideration in the assessment of a holistic treatment response. SCS device data and how it relates to patient outcomes, is essential to improve the understanding of the different types of SCS, improve patient selection, long-term clinical outcomes, and reproducibility of findings. The outcomes to include in the evaluation of a holistic treatment response need to consider clinical relevance for patients and clinicians. Assessment of the holistic response combines two key concepts of patient assessment: (1) patients level of baseline (pre-treatment) unmet need across a range of health domains; (2) demonstration of patient-relevant improvements in these health domains with treatment. The minimal clinical important difference (MCID) is an established approach to reflect changes after a clinical intervention that are meaningful for the patient and can be used to identify treatment response to each individual domain. A holistic treatment response needs to account for MCIDs in all domains of importance for which the patient presents dysfunctional scores pre-treatment. The number of domains included in a holistic treatment response may vary and should be considered on an individual basis. Physiologic confirmation of therapy delivery and utilisation should be included as part of the evaluation of a holistic treatment response and is essential to advance the field of SCS and increase transparency and reproducibility of the findings.

Anti-seizure medication exposure and the risk of dementia: A meta-analysis of observational studies

Objective

There is growing evidence of a relationship between anti-seizure medication (ASM) use and the risk of dementia. This study examined this association using a meta-analysis approach.

Methods

PubMed, EMBASE, and Cochrane Library were systematically searched for peer-reviewed observational studies published up to February 2023. Study quality was evaluated using the Newcastle-Ottawa Scale, and an overall odds ratio (OR) was pooled using fixed or random-effects models.

Results

The analysis included 9 publications with 10 studies. The results showed that overall ASM exposure was associated with an increased risk of dementia [OR: 1.09, 95% confidence interval (CI): 1.03-1.15; P = 0.003] in general population. However, this association disappeared (OR: 1.02, 95% CI: 0.97-1.07; P = 0.361) when the study data adjusted for drug indications were pooled. Subgroup analysis based on individual drugs found only a positive association among those exposed to valproate, carbamazepine, and clonazepam. Furthermore, an increased risk was found in patients with bipolar disorder exposed to ASMs (OR: 1.43, 95% CI: 1.07-1.92; P = 0.015).

Conclusions

The statistically significant association between ASM and dementia in general population may be driven by unmeasured confounding or several individual first-generation ASMs. However, a higher risk of dementia was observed among bipolar disorder patients treated with ASMs. Given the few included studies and evidence of high heterogeneity, further larger, prospective studies that control for important confounders are needed to verify our findings.

Flexible realistic simulation of seizure occurrence recapitulating statistical properties of seizure diaries

OBJECTIVE

A realistic seizure diary simulator is currently unavailable for many research needs, including clinical trial analysis and evaluation of seizure detection and seizure-forecasting tools. In recent years, important statistical features of seizure diaries have been characterized. These include (1) heterogeneity of individual seizure frequencies, (2) the relation between average seizure rate and standard deviation, (3) multiple risk cycles, (4) seizure clusters, and (5) limitations on inter-seizure intervals. The present study unifies these features into a single model.

METHODS

Our approach, Cyclic Heterogeneous Overdispersed Clustered Open-source L-relationship Adjustable Temporally limited E-diary Simulator (CHOCOLATES) is based on a hierarchical model centered on a gamma Poisson generator with several modifiers. This model accounts for the aforementioned statistical properties. The model was validated by simulating 10 000 randomized clinical trials (RCTs) of medication to compare with 23 historical RCTs. Metrics of 50% responder rate (RR50) and median percent change (MPC) were evaluated. We also used CHOCOLATES as input to a seizure-forecasting tool to test the flexibility of the model. We examined the area under the receiver-operating characteristic (ROC) curve (AUC) for test data with and without cycles and clusters.

RESULTS

The model recapitulated typical findings in 23 historical RCTs without the necessity of introducing an additional "placebo effect." The model produced the following RR50 values: placebo: 17 ± 4%; drug 38 ± 5%; and the following MPC values: placebo: 13 ± 6%; drug 40 ± 4%. These values are similar to historical data: for RR50: placebo, 21 ± 10%, drug: 43 ± 13%; and for MPC: placebo: 17 ± 10%, drug: 41 ± 11%. The seizure forecasts achieved an AUC of 0.68 with cycles and clusters, whereas without them the AUC was 0.51.

SIGNIFICANCE

CHOCOLATES represents the most realistic seizure occurrence simulator to date, based on observations from thousands of patients in different contexts. This tool is open source and flexible, and can be used for many applications, including clinical trial simulation and testing of seizure-forecasting tools.

Pregabalin Add-On vs. Dose Increase in Levetiracetam Add-On Treatment: A Real-Life Trial in Dogs With Drug-Resistant Epilepsy

Epilepsy is a common neurological disorder affecting 0.6–0.75% of dogs in veterinary practice. Treatment is frequently complicated by the occurrence of drug-resistant epilepsy and cluster seizures in dogs with idiopathic epilepsy. Only few studies are available to guide treatment choices beyond licensed veterinary drugs. The aim of the study was to compare antiseizure efficacy and tolerability of two add-on treatment strategies in dogs with drug-resistant idiopathic epilepsy. The study design was a prospective, open-label, non-blinded, comparative treatment trial. Treatment success was defined as a 3-fold extension of the longest baseline interseizure interval and to a minimum of 3 months. To avoid prolonged adherence to a presumably ineffective treatment strategy, dog owners could leave the study after the third day with generalized seizures if the interseizure interval failed to show a relevant increase. Twenty-six dogs (mean age 5.5 years, mean seizure frequency 4/month) with drug-resistant idiopathic epilepsy and a history of cluster seizures were included. Dogs received either add-on treatment with pregabalin (PGB) 4 mg/kg twice daily (14 dogs) or a dose increase in levetiracetam (LEV) add-on treatment (12 dogs). Thirteen dogs in the PGB group had drug levels within the therapeutic range for humans. Two dogs in the PGB group (14.3%; 2/14) and one dog in the LEV group (8.3%; 1/12) achieved treatment success with long seizure-free intervals from 122 to 219 days but then relapsed to their early seizure frequency 10 months after the study inclusion. The overall low success rates with both treatment strategies likely reflect a real-life situation in canine drug-resistant idiopathic epilepsy in everyday veterinary practice. These results delineate the need for research on better pharmacologic and non-pharmacologic treatment strategies in dogs with drug-resistant epilepsy.

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, levetiracetam 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 levetiracetam (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 levetiracetam (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.

Pregabalin abuse and dependence during insomnia and protocol for short-term withdrawal management with diazepam: examples from case reports

Introduction:

Pregabalin (PGN) is an anxiolytic, analgesic, antiepileptic, and hypnotic medication. There are concerns about its abuse in the community for managing chronic insomnia and other risks when assumed in overdose or combination with other abuse substances. PGN is classified as a controlled medication. While its discontinuation is accompanied by rebound insomnia and other neurological symptoms, cross-tapering PGN with short-term diazepam (DZ) during inpatient admissions has shown promising results in dealing with PGN withdrawal symptoms accompanied by rebound insomnia.

Material and Methods:

We report three cases that began abusing their prescribed PGN. During hospital admission, our teams used a protocol for cross-tapering PGN with DZ to reduce withdrawal symptoms. Other sedative medications are suspended while alcohol is not allowed if patients are on leave from the hospital. Standardized scales for assessment were clinical global impression scale-severity (CGI-S), generalized anxiety disorder scale (GAD-7), and insomnia severity index (ISI).

Results:

The cross-tapering PGN with DZ showed similar clinical outcomes with reduced withdrawal symptoms and rebound insomnia during two weeks of cross-tapering. Eventually, DZ, too, is stopped in the hospital to avoid another dependence syndrome.

Conclusion:

As emerging in the current study, PGN has strong addictive effects in people who have insomnia and is mostly abused for its hypnotic or sleep-inducing properties when other medications have failed. As applied in the current study, DZ can manage PGN withdrawal symptoms with rebound insomnia while cross-tapering. DZ is then discontinued.

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.

Anti-seizure medications and efficacy against focal to bilateral tonic-clonic seizures: A systematic review with relevance for SUDEP prevention

We conducted a systematic review of anti-seizure medications (ASMs) and their efficacy for the control of focal to bilateral tonic-clonic seizures (FBTCS). FBTCS, especially when nocturnal, are recognized as one of the major risk factors for Sudden Unexpected Death in Epilepsy (SUDEP). We searched different online databases for all the randomized, double-blinded, and placebo-controlled clinical trials of ASMs that were FDA-approved after 1990 and that reported specifically on the reduction in FBTCS; when possible, this was compared to reduction in focal impaired awareness (FIA) seizures. The ASMs that yielded the most data (3 or more studies) were topiramate (TPM), followed by tiagabine (TGB), brivaracetam (BRV), and lamotrigine (LTG). TPM trials showed a reduction in FBTCS of 44.8% to 100% (4.5-99% over placebo); TGB 21.8% to 46.7% (21.8-61% over placebo); BRV 33.9% to 82.1% (11.6-57.4% over placebo); and LTG 55.2% (20.3-52% over placebo). Promising results, but with data from only one or two studies, were seen with cenobamate (18-59% efficacy above placebo), lacosamide (45.1-78.7%), levetiracetam (40.1-60.3%), oxcarbazepine (58.5-81.5%), and gabapentin (50-53.8%). Higher responses were often seen at higher doses, including at doses above those currently approved by the FDA. Results specific to nocturnal FBTCS were never reported for any ASM. Moreover, complete freedom from FBTCS specifically was very rarely reported, despite its relevance for SUDEP prevention. In conclusion, there are few data specifically comparing the efficacy of ASMs for prevention of FBTCS despite the known strong association of BTCS with SUDEP. This review was our attempt at filling a gap in the literature and calling for universal reporting of data specific to BTC seizure reduction in all future studies, preferably including specific reporting on nocturnal BTCS. This will help enable rational ASM selection to minimize BTC seizures and thereby decrease the risk of SUDEP.

A meta-analysis: efficacy and safety of anti-epileptic drugs prescribed in Korea as monotherapy and adjunctive treatment for patients with focal epilepsy

Focal epilepsy is the most common type of epilepsy in Korea, and anti-epileptic drugs (AEDs) are the main treatment option for patients. This study aimed to compare the efficacy and safety of AEDs for focal epilepsy through a meta-analysis. The AEDs prescribed in Korea as monotherapy and adjunctive treatment for patients with focal epilepsy were included for analysis. Relevant articles were searched for randomized clinical trials of AEDs and treatment outcomes were analyzed on the basis of the 50% responder rate, seizure-free rate, treatment withdrawal rate, and emergence rates of adverse events (AEs). The odds ratios (ORs) and their 95% confidence intervals (CI) of study outcome were calculated using combined data from multiple studies. A total of 47 studies were included in the meta-analysis. The seizure-free rate, treatment withdrawal rate, and AE rate were not significantly different among the AEDs recommended for monotherapy. Among the AEDs recommended for adjunctive treatment, topiramate and oxcarbazepine yielded the highest OR in comparison with placebo for each efficacy parameter: the 50% responder rate for topiramate = 6.42 (3.76–11.6) and the seizure-free rate for oxcarbazepine = 32.7 (6.05–899). The third-generation AEDs (brivaracetam and perampanel) yielded relatively better safety outcomes than other AEDs. In general, the 50% responder rate and treatment withdrawal rate tended to increase as the dose of the AEDs increased. The results from the current meta-analysis of the efficacy and safety data of various AEDs may provide insight into optimal pharmacotherapy for the treatment of focal epilepsy.

Pregabalin Population Pharmacokinetic and Exposure-Response Analyses for Focal Onset Seizures in Children (4-16 years) and Adults, to Support Dose Recommendations in Children

Pregabalin is approved in multiple countries as adjunctive therapy for adult patients with focal onset seizures (FOS; previously termed partial onset seizures). This study used population pharmacokinetic (PK) and exposure–response (E‐R) analyses from pooled pregabalin concentration and efficacy data to compare pregabalin exposure and E‐R relationships in pediatric and adult patients with FOS, to support pediatric dosage recommendations. A one‐compartment disposition model was used, with first‐order absorption and body surface area‐normalized creatinine clearance on clearance. Individual pregabalin average steady‐state concentrations were predicted and used in an E‐R analysis of efficacy. The E‐R relationship of pregabalin was similar in pediatric (4–16 years) and adult patients with FOS after accounting for differences in baseline natural log‐transformed 28‐day seizure rate and placebo effect. Population PK simulations showed that children aged 4–16 years and weighing ≥ 30 kg required pregabalin 2.5–10 mg/kg/day to achieve similar pregabalin exposure at steady‐state to adult patients receiving the approved doses of 150–600 mg/day. For children 4–16 years weighing < 30 kg, a higher pregabalin dose of 3.5–14 mg/kg/day was required to achieve equivalent exposure at steady‐state. The results support the dosage guidance provided in the pregabalin prescribing label, whereby pediatric patients (4–16 years) weighing < 30 kg should receive a 40% higher pregabalin dose (per kg of body weight) than patients weighing ≥ 30 kg to achieve similar exposure. Our combined modeling approach may provide guidance for future extrapolation assessment from adult to pediatric patients.

Natural variability in seizure frequency: Implications for trials and placebo

BACKGROUND

Changes in patient-reported seizure frequencies are the gold standard used to test efficacy of new treatments in randomized controlled trials (RCTs). Recent analyses of patient seizure diary data suggest that the placebo response may be attributable to natural fluctuations in seizure frequency, though the evidence is incomplete. Here we develop a data-driven statistical model and assess the impact of the model on interpretation of placebo response.

METHODS

A synthetic seizure diary generator matching statistical properties seen across multiple epilepsy diary datasets was constructed. The model was used to simulate the placebo arm of 5000 RCTs. A meta-analysis of 23 historical RCTs was compared to the simulations.

RESULTS

The placebo 50 %-responder rate (RR50) was 27.3 ± 3.6 % (simulated) and 21.1 ± 10.0 % (historical). The placebo median percent change (MPC) was 22.0 ± 6.0 % (simulated) and 16.7 ± 10.3 % (historical).

CONCLUSIONS

A statistical model of daily seizure count generation which incorporates quantities related to the natural fluctuations of seizure count data produces a placebo response comparable to those seen in historical RCTs. This model may be useful in better understanding the seizure count fluctuations seen in patients in other clinical settings.

Pregabalin-associated movement disorders: A literature review

Central nervous system adverse effects are commonly reported with pregabalin (PGB). On the other hand, movement disorders (MDs) associated with this drug were rarely described. However, their occurrence could significantly affect the quality of life of PGB users. This literature review aims to evaluate the clinical epidemiological profile, pathological mechanisms, and management of PGB-associated MDs. Relevant reports in six databases were identified and assessed by two reviewers without language restriction. A total of 46 reports containing 305 cases from 17 countries were assessed. The MDs encountered were as follows: 184 individuals with ataxia, 61 with tremors, 39 with myoclonus, 8 with parkinsonism, 1 with restless legs syndrome, 1 with dystonia, 1 with dyskinesia, and 1 with akathisia. The mean age was 62 years (range: 23-94). The male sex was slightly predominant with 54.34%. The mean PGB dose when the MD occurred was 238 mg, and neuropathic pain was the most common indication of PGB. The time from PGB start to MD was < 1 month at 75%. The time from PGB withdrawal to recovery was < 1 week at 77%. All the individuals where the follow-up was reported had a full recovery. The most common management was PGB withdrawal. In the literature, the majority of the cases did not report information about timeline events, neurological examination details, or electrodiagnostic studies. The best management for all MDs is probably PGB withdrawal. If the patient is on dialysis program, perhaps an increased number of sessions will decrease recovery time. Furthermore, the addition of a benzodiazepine could accelerate recovery.

Pregabalin adjunctive therapy for focal onset seizures in children 1 month to <4 years of age: A double-blind, placebo-controlled, video-electroencephalographic trial

OBJECTIVE

To evaluate the efficacy and safety of pregabalin as adjunctive treatment for children (aged 1 month-<4 years) with focal onset seizures (FOS) using video-electroencephalography (V-EEG).

METHODS

This randomized, placebo-controlled, international study included V-EEG seizure monitoring (48-72 hours) at baseline and over the last 3 days of 14-day (5-day dose escalation; 9-day fixed dose) double-blind pregabalin treatment (7 or 14 mg/kg/d in three divided doses). This was followed by a double-blind 1-week taper. The primary efficacy endpoint was log-transformed seizure rate (log_e [24-hour seizure rate + 1]) for all FOS recorded during the double-blind V-EEG monitoring, evaluated in subjects who took ≥1 dose of study medication, experienced ≥1 baseline seizure(s), and had a treatment phase V-EEG. Safety and tolerability were assessed by adverse events (AEs), clinical laboratory data, physical/neurological examinations, vital signs, and electrocardiograms.

RESULTS

Overall, 175 patients were randomized (mean age = 28.2 months; 59% male, 69% white, 30% Asian) in a 2:1:2 ratio to pregabalin 7 or 14 mg/kg/d (n = 71 or n = 34, respectively), or placebo (n = 70). Pregabalin 14 mg/kg/d (n = 28) resulted in a statistically significant 35% reduction of log_e (24-hour seizure rate + 1) versus placebo (n = 53; P = .022), an effect that was not observed with pregabalin 7 mg/kg/d (n = 59; P = .461). The most frequently reported treatment-emergent AEs for pregabalin 7 mg/kg/d, 14 mg/kg/d, and placebo, respectively, were somnolence (11.3%, 17.6%, and 5.7%) and upper respiratory tract infection (7.0%, 11.8%, and 11.4%). All AEs were mild to moderate in severity.

SIGNIFICANCE

Pregabalin 14 mg/kg/d (but not 7 mg/kg/d) significantly reduced seizure rate in children with FOS, when assessed using V-EEG, compared with placebo. Both pregabalin dosages were generally safe and well tolerated in children 1 month to <4 years of age with FOS. Safety and tolerability were consistent with the known profile of pregabalin in older children with epilepsy.

Development of a Novel Controlled-Release Tablet of Pregabalin: Formulation Variation and Pharmacokinetics in Dogs and Humans

Background

Novel three-layered (TL) tablet systems were compared with both monolithic matrix (MM) formulations and a commercial immediate-release (IR) capsule to develop once-a-day (OAD) pregabalin tablets.

Methods

The physical properties of the TL tablets, including dissolution and swelling rates, were compared with those of the MM tablets and the pharmacokinetic parameters of the TL tablet were compared with those of an IR capsule in beagles and humans.

Results

Our results indicated that the same amount of a hydrophilic polymer in the formulations had similar dissolution profiles at 12 h, regardless of the tablet geometry. However, the degree of tablet swelling differed, with larger amounts of polymer in the tablets showing a greater degree of swelling. In addition, TL tablets swelled more rapidly compared with MM tablets. For the pharmacokinetic study of the TL tablet, the beagles demonstrated absorption results similar to those of an IR capsule, whereas the humans demonstrated low total absorption compared with an IR capsule. The time of the peak plasma concentration at 6 h in the fed state of humans coincided with the results of the study on beagles.

Conclusion

The novel TL tablet system of pregabalin may prove to be helpful in developing improved formulations with better continuous drug absorption for OAD administration.

Immediate and controlled-release pregabalin for the treatment of epilepsy

Introduction: Epilepsy is a common neurological disease requiring complex therapies, which are unable to achieve seizure control in 30% of patients. Poor adherence has been recognized as a possible determinant of drug-resistance. Prolonged-release formulations of antiepileptic drugs might help increase adherence and minimize side effects.Areas covered: Pregabalin (PGB) has peculiar pharmacodynamics and almost ideal pharmacokinetics, except for a short half-life and therefore requiring multiple daily dosing. PGB immediate-release (IR) is effective in focal-onset epilepsy (FOE), neuropathic pain, generalized anxiety disorder, and fibromyalgia, despite some tolerability issues, especially at higher doses. The controlled-release formulation (CR) shares PGB IR advantages and requires slight dose adjustments to guarantee bioavailability. In 2014, PGB CR (165 and 330 mg/day) failed to prove superior to placebo in a randomized placebo-controlled trial on 323 subjects with drug-resistant FOE, although it was just as tolerable. Therefore, PGB CR is not currently licensed for epilepsy.Expert opinion: Considering the disappointing results of the only controlled trial, PGB CR is unlikely to become an established epilepsy treatment anytime soon. Nevertheless, given its peculiar properties and potential advantages, PGB (in either formulation) should be further evaluated in specific populations of patients, especially fragile subjects with several comorbidities and complex polytherapies.

Pregabalin add-on for drug-resistant focal epilepsy

BACKGROUND

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 which have been developed to improve outcomes.This is an updated version of the Cochrane Review published in Issue 3, 2014, and includes three new studies.

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 Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL), on 5 July 2018, MEDLINE (Ovid, 1946 to 5 July 2018), ClinicalTrials.gov (5 July 2018), and the World Health Organization International Clinical Trials Registry Platform (ICTRP, 5 July 2018), and contacted Pfizer Ltd, manufacturer of pregabalin, to identify published, unpublished, and ongoing trials.

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 and assessed trials for eligibility and extracted data. Analyses were by intention-to-treat. We presented results as risk ratios (RR) and odds ratios (OR) with 95% confidence intervals (CIs). Two review authors assessed the included studies for risk of bias using the Cochrane 'Risk of bias' tool.

MAIN RESULTS

We included nine industry-sponsored randomised controlled trials (3327 participants) in the review. Seven 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 2.28, 95% CI 1.52 to 3.42, 7 trials, 2193 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 1.35, 95% CI 1.11 to 1.65, 7 trials, 2193 participants, moderate-certainty evidence) and for adverse effects (RR 2.65, 95% CI 1.88 to 3.74, 7 trials, 2193 participants, moderate-certainty evidence).Three trials compared pregabalin to three active-control drugs: lamotrigine, levetiracetam, 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 levetiracetam (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 (RR 1.39, 95% CI 0.40 to 4.83) for seizure freedom, however, significantly fewer participants achieved seizure freedom with add-on pregabalin compared to levetiracetam (RR 0.50, 95% CI 0.30 to 0.85). No data were reported for this outcome for pregabalin versus gabapentin. We found no significant differences between pregabalin and lamotrigine (RR 1.07, 95% CI 0.75 to 1.52), levetiracetam (RR 1.03, 95% CI 0.71 to 1.49), or gabapentin (RR 0.78, 95% CI 0.57 to 1.07) for treatment withdrawal due to any reason or due to adverse effects (pregabalin versus lamotrigine: RR 0.89, 95% CI 0.53 to 1.48; versus levetiracetam: RR 1.29, 95% CI 0.66 to 2.54; versus gabapentin: RR 1.07, 95% CI 0.54 to 2.11). Ataxia, dizziness, somnolence, weight gain, and fatigue were significantly associated with pregabalin.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 rated the certainty of the evidence as very low to moderate using the GRADE approach.

AUTHORS' CONCLUSIONS

Pregabalin, when used as an add-on drug for treatment-resistant focal epilepsy, is 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, however issues with tolerability were noted at higher doses. The trials included in this review were of short duration, and longer-term trials are needed to inform clinical decision making.

Pregabalin as Adjunctive Treatment for Focal Onset Seizures in Pediatric Patients: A Randomized Controlled Trial

Efficacy and safety of pregabalin as adjunctive treatment for children (aged 4-16 years) with partial-onset seizures, hereafter termed focal onset seizures for this study, was evaluated. This double-blind, randomized, placebo-controlled, international study had 3 phases: 8-week baseline, 12-week double-blind treatment (2-week dose escalation; 10-week fixed dose), and 1-week taper. Selection criteria included experiencing focal onset seizures and receiving a stable regimen of 1 to 3 antiepileptic drugs. Study treatments were pregabalin 2.5 mg/kg/d, 10 mg/kg/d, or placebo; doses were increased to 3.5 or 14 mg/kg/d for subjects weighing <30 kg. The key endpoints were change in log_e(28-day seizure rate), achieving a ≥50% seizure responder rate, safety, and tolerability during double-blind treatment. Subjects (n = 295; mean age 10.2 years, 55% male, 69% white) were randomized to pregabalin 2.5 mg/kg/d (n = 104), 10 mg/kg/d (n = 97), or placebo (n = 94). A statistically significant reduction in log_e(28-day seizure rate) was demonstrated with pregabalin 10 mg/kg/d (a 19.9% improvement over placebo; P = .0185). Seizure frequency was numerically improved (statistically nonsignificant) with pregabalin 2.5 mg/kg/d ( P = .2577). Responder rate significantly favored pregabalin 10 mg/kg/d (40.6%, P = .0068) compared with placebo (22.6%) and was numerically improved with pregabalin 2.5 mg/kg/d (29.1%, P = .2600). Common adverse events (≥10% of any group) in 10 mg/kg/d, 2.5 mg/kg/d, and placebo groups, respectively, included somnolence (25.8%, 17.3%, 13.8%), increased weight (13.4%, 3.8%, 4.3%), and increased appetite (10.3%, 6.7%, 4.3%). Pregabalin 10 mg/kg/d demonstrated efficacy in seizure frequency reduction in children with focal onset seizures compared with placebo, and both pregabalin doses were generally safe and well tolerated. www.clinicialtrials.gov identifier NCT01389596; EudraCT #2010-020852-79.

Efficacy of antiepileptic drugs in the adjunctive treatment of refractory partial-onset seizures: Meta-analysis of pivotal trials

OBJECTIVE

In the absence of randomized clinical trials (RCTs) assessing the relative efficacy of antiepileptic drugs (AEDs), meta-analyses are useful resources for informing treatment choices. This meta-analysis assesses the relative efficacy and tolerability of AEDs for adjunctive treatment of refractory partial onset seizures (POS).

METHODS

A systematic literature review was conducted to identify pivotal AED trials serving as the basis for US Food and Drug Administration (FDA) approval.

INCLUSION CRITERIA

1) double-blind, placebo-controlled, parallel-group design, with 8- to 14-week maintenance period; 2) enrolled patients ≥16years with refractory POS, including complex partial seizures; 3) study was conducted between 1993 and 2013; and; 4) patients received FDA-approved dosage. Outcomes analyzed: 1) 50% responder rate (≥50% reduction from baseline in seizure frequency); 2) seizure freedom (proportion of seizure-free patients); and 3) discontinuation due to adverse events (AEs). DerSimonian and Laird random-effects model was used to derive odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

A total of 29 publications for 11 AEDs (eslicarbazepine, ezogabine, gabapentin, lacosamide, levetiracetam, perampanel, pregabalin, tiagabine, topiramate, vigabatrin, and zonisamide) were included in the meta-analysis. Tiagabine 56mg/day (OR 8.82, 95% CI: 2.77-28.11), pregabalin 600mg/day (OR 8.08, 95% CI: 5.45-11.98), and vigabatrin 3000mg/day (OR 6.23, 95% CI: 1.46-26.20) had the highest OR versus placebo of 50% response. The odds of seizure freedom were ≥7 times greater than placebo for levetiracetam 3000mg/day (OR 11.00, 95% CI: 2.08-58.06), vigabatrin 3000mg/day (OR 7.41, 95% CI: 1.31-41.84), and ezogabine 1200mg/day (OR 7.09, 95% CI: 0.36-58.06). Patients were more likely to discontinue any AED (except low-dose pregabalin) than placebo.

CONCLUSION

In this meta-analysis of >9000 patients, those treated with AEDs were more likely than placebo to achieve seizure response or freedom. Patients receiving pregabalin, tiagabine, and vigabatrin had the highest odds of ≥50% reduction in seizures, and patients receiving ezogabine, levetiracetam, and vigabatrin had the highest odds of seizure freedom.

Pregabalin-associated Discontinuation Symptoms: A Case Report

Pregabalin is used for the treatment of neuropathic pain, partial seizures, generalized anxiety disorder, social anxiety disorder, and insomnia. The discontinuation symptoms of pregabalin are mild to moderate which resolve in about one week after the discontinuation of pregabalin. This case report describes the withdrawal symptoms in a 62-year-old patient despite a slow titration over a period of several weeks. It highlights the importance of cautious monitoring of withdrawal symptoms during the period of taper.

Practice guideline update summary: Efficacy and tolerability of the new antiepileptic drugs II: Treatment-resistant epilepsy: Report of the American Epilepsy Society and the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology

Objective: To update the 2004 American Academy of Neurology (AAN) guideline for managing treatment-resistant (TR) epilepsy with second- and third-generation antiepileptic drugs (AEDs). Methods: 2004 criteria were used to systematically review literature (January 2003 to November 2015), classify pertinent studies according to the therapeutic rating scheme, and link recommendations to evidence strength. Results: Forty-two articles were included. Recommendations: The following are established as effective to reduce seizure frequency (Level A): immediate-release pregabalin and perampanel for TR adult focal epilepsy (TRAFE); vigabatrin for TRAFE (not first-line treatment; rufinamide for Lennox-Gastuat syndrome (LGS) (add-on therapy). The following should be considered to decrease seizure frequency (Level B): lacosamide, eslicarbazepine, and extended-release topiramate for TRAFE (ezogabine production discontinued); immediate- and extended-release lamotrigine for generalized epilepsy with TR generalized tonic-clonic (GTC) seizures in adults; levetiracetam (add-on therapy) for TR childhood focal epilepsy (TRCFE) (1 month to 16 years), TR GTC seizures, and TR juvenile myoclonic epilepsy; clobazam for LGS (add-on therapy); zonisamide for TRCFE (6-17 years); oxcarbazepine for TRCFE (1 month to 4 years). The text presents Level C recommendations. AED selection depends on seizure/syndrome type, patient age, concomitant medications, and AED tolerability, safety, and efficacy. This evidence-based assessment informs AED prescription guidelines for TR epilepsy and indicates seizure types and syndromes needing more evidence. A recent FDA strategy allows extrapolation of efficacy across populations; therefore, for focal epilepsy, eslicarbazepine and lacosamide (oral only for pediatric use) as add-on or monotherapy in persons ≥4 years of age and perampanel as monotherapy received FDA approval.

Practice guideline update summary: Efficacy and tolerability of the new antiepileptic drugs II: Treatment-resistant epilepsy

Objective

To update the 2004 American Academy of Neurology guideline for managing treatment-resistant (TR) epilepsy with second- and third-generation antiepileptic drugs (AEDs).

Methods

2004 criteria were used to systemically review literature (January 2003 to November 2015), classify pertinent studies according to the therapeutic rating scheme, and link recommendations to evidence strength.

Results

Forty-two articles were included.

Recommendations

The following are established as effective to reduce seizure frequency (Level A): immediate-release pregabalin and perampanel for TR adult focal epilepsy (TRAFE); vigabatrin for TRAFE (not first-line treatment); rufinamide for Lennox-Gastaut syndrome (LGS) (add-on therapy). The following should be considered to decrease seizure frequency (Level B): lacosamide, eslicarbazepine, and extended-release topiramate for TRAFE (ezogabine production discontinued); immediate- and extended-release lamotrigine for generalized epilepsy with TR generalized tonic-clonic (GTC) seizures in adults; levetiracetam (add-on therapy) for TR childhood focal epilepsy (TRCFE) (1 month–16 years), TR GTC seizures, and TR juvenile myoclonic epilepsy; clobazam for LGS (add-on therapy); zonisamide for TRCFE (6–17 years); oxcarbazepine for TRCFE (1 month–4 years). The text presents Level C recommendations. AED selection depends on seizure/syndrome type, patient age, concomitant medications, and AED tolerability, safety, and efficacy. This evidence-based assessment informs AED prescription guidelines for TR epilepsy and indicates seizure types and syndromes needing more evidence. A recent Food and Drug Administration (FDA) strategy allows extrapolation of efficacy across populations; therefore, for focal epilepsy, eslicarbazepine and lacosamide (oral only for pediatric use) as add-on or monotherapy in persons ≥4 years of age and perampanel as monotherapy received FDA approval.

Challenges of the pharmacological management of benzodiazepine withdrawal, dependence, and discontinuation

BACKGROUND

Benzodiazepines (BZDs) are among the most prescribed sedative hypnotics and among the most misused and abused medications by patients, in parallel with opioids. It is estimated that more than 100 million Benzodiazepine (BZD) prescriptions were written in the United States in 2009. While medically useful, BZDs are potentially dangerous. The co-occurring abuse of opioids and BZD, as well as increases in BZD abuse, tolerance, dependence, and short- and long-term side effects, have prompted a worldwide discussion about the challenging aspects of medically managing the discontinuation of BZDs. Abrupt cessation can cause death. This paper addresses the challenges of medications suggested for the management of BZD discontinuation, their efficacy, the risks of abuse and associated medical complications. The focus of this review is on the challenges of several medications suggested for the management of BZD discontinuation, their efficacy, the risks of abuse, and associated medical complications.

METHODS

An electronic search was performed of Medline, Worldwide Science, Directory of Open Access Journals, Embase, Cochrane Library, Google Scholar, PubMed Central, and PubMed from 1990 to 2017. The review includes double-blind, placebo-controlled studies for the most part, open-label pilot studies, and animal studies, in addition to observational research. We expand the search to review articles, naturalistic studies, and to a lesser extent, letters to the editor/case reports. We exclude abstract and poster presentations, books, and book chapters.

RESULTS

The efficacy of these medications is not robust. While some of these medicines are relatively safe to use, some of them have a narrow therapeutic index, with severe, life-threatening side effects. Randomized studies have been limited. There is a paucity of comparative research. The review has several limitations. The quality of the documents varies according to whether they are randomized studies, nonrandomized studies, naturalistic studies, pilot studies, letters to the editors, or case reports.

CONCLUSIONS

The use of medications for the discontinuation of BZDs seems appropriate. It is a challenge that requires further investigation through randomized clinical trials to maximize efficacy and to minimize additional risks and side effects.

Protein complexes as psychiatric and neurological drug targets

The need for improved medications for psychiatric and neurological disorders is clear. Difficulties in finding such drugs demands that all strategic means be utilized for their invention. The discovery of forebrain specific AMPA receptor antagonists, which selectively block the specific combinations of principal and auxiliary subunits present in forebrain regions but spare targets in the cerebellum, was recently disclosed. This discovery raised the possibility that other auxiliary protein systems could be utilized to help identify new medicines. Discussion of the TARP-dependent AMPA receptor antagonists has been presented elsewhere. Here we review the diversity of protein complexes of neurotransmitter receptors in the nervous system to highlight the broad range of protein/protein drug targets. We briefly outline the structural basis of protein complexes as drug targets for G-protein-coupled receptors, voltage-gated ion channels, and ligand-gated ion channels. This review highlights heterodimers, subunit-specific receptor constructions, multiple signaling pathways, and auxiliary proteins with an emphasis on the later. We conclude that the use of auxiliary proteins in chemical compound screening could enhance the detection of specific, targeted drug searches and lead to novel and improved medicines for psychiatric and neurological disorders.

Glial source of nitric oxide in epileptogenesis: A target for disease modification in epilepsy

Epileptogenesis is the process of developing an epileptic condition and/or its progression once it is established. The molecules that initiate, promote, and propagate remarkable changes in the brain during epileptogenesis are emerging as targets for prevention/treatment of epilepsy. Epileptogenesis is a continuous process that follows immediately after status epilepticus (SE) in animal models of acquired temporal lobe epilepsy (TLE). Both SE and epileptogenesis are potential therapeutic targets for the discovery of anticonvulsants and antiepileptogenic or disease-modifying agents. For translational studies, SE targets are appropriate for screening anticonvulsive drugs prior to their advancement as therapeutic agents, while targets of epileptogenesis are relevant for identification and development of therapeutic agents that can either prevent or modify the disease or its onset. The acute seizure models do not reveal antiepileptogenic properties of anticonvulsive drugs. This review highlights the important components of epileptogenesis and the long-term impact of intervening one of these components, nitric oxide (NO), in rat and mouse kainate models of TLE. NO is a putative pleotropic gaseous neurotransmitter and an important contributor of nitro-oxidative stress that coexists with neuroinflammation and epileptogenesis. The long-term impact of inhibiting the glial source of NO during early epileptogenesis in the rat model of TLE is reviewed. The importance of sex as a biological variable in disease modification strategies in epilepsy is also briefly discussed.

The Effect of Preoperative Pregabalin on Postoperative Nausea and Vomiting: A Meta-analysis

BACKGROUND

Nonopioid adjuvant medications are increasingly included among perioperative Enhanced Recovery After Surgery protocols. Preoperative pregabalin has been shown to improve postoperative pain and limit reliance on opioid analgesia. Our group investigated the ability of preoperative pregabalin to also prevent postoperative nausea and vomiting (PONV).

METHODS

Our group performed a meta-analysis of randomized trials that report outcomes on the effect of preoperative pregabalin on PONV endpoints in patients undergoing general anesthesia.

RESULTS

Among all included trials (23 trials; n = 1693), preoperative pregabalin was associated with a significant reduction in PONV (risk ratio [RR] = 0.53; 95% confidence interval [CI], 0.39-0.73; P = 0.0001), nausea (RR = 0.62; 95% CI, 0.46-0.83; P = 0.002), and vomiting (RR = 0.68; 95% CI, 0.52-0.88; P = 0.003) at 24 hours. Subgroup analysis designed to account for major PONV confounders, including the exclusion trials with repeat dosing, thiopental induction, nitrous oxide maintenance, and prophylactic antiemetics and including high-risk surgery, resulted in similar antiemetic efficacy. Preoperative pregabalin is also associated with significantly increased rates of postoperative visual disturbance (RR = 3.11; 95% CI, 1.34-7.21; P = 0.008) compared with a control.

CONCLUSIONS

Preoperative pregabalin is associated with significant reduction of PONV and should not only be considered as part of a multimodal approach to postoperative analgesia but also for prevention of PONV.

Seizure induced by sudden cessation of pregabalin in a patient with chronic kidney disease

A middle-aged woman with diabetic nephropathy on pregabalin for neuropathic pain presented with a diarrhoeal illness. She was found to have acute on chronic renal impairment with an estimated glomerular filtration rate (eGFR) of 10 mL/min, and her usual 150 mg/day of pregabalin was abruptly ceased. Although renal recovery to her baseline of eGFR 15 mL/min was achieved within 3 days, her pregabalin was not restarted. She suffered a tonic-clonic seizure 4 days later, thought to be due to pregabalin withdrawal as there were no other likely causes identified. She suffered no further seizures on recommencement of pregabalin at a renally adjusted dose of 75 mg/day.

Association between antiepileptic drug dose and long-term response in patients with refractory epilepsy

Seizures in patients with medically refractory epilepsy remain a substantial clinical challenge, not least because of the dearth of evidence-based guidelines as to which antiepileptic drug (AED) regimens are the most effective, and what doses of these drugs to employ. We sought to determine whether there were regions in the dosage range of commonly used AEDs that were associated with superior efficacy in patients with refractory epilepsy. We retrospectively analyzed treatment records from 164 institutionalized, developmentally disabled patients with refractory epilepsy, averaging 17years of followup per patient. We determined the change in seizure frequency in within-patient comparisons during treatment with the most commonly used combinations of 12 AEDs, and then analyzed the response to treatment by quartile of the dose range for monotherapy with carbamazepine (CBZ), lamotrigine (LTG), valproate (VPA), or phenytoin (PHT), and the combination LTG/VPA. We found that of the 26 most frequently used AED regimens, only LTG/VPA yielded superior efficacy, similar to an earlier study. For the monotherapies, patients who were treated in the lowest quartile of the dose range had significantly better long-term reduction in seizure frequency compared to those treated in the 2nd and 3rd quartiles of the dose range. Patients with paired exposures to CBZ in both the lowest quartile and a higher quartile of dose range experienced an increase in seizure frequency at higher doses, while patients treated with LTG/VPA showed improved response with escalation of LTG dosage. We conclude that in this population of patients with refractory epilepsy, LTG/VPA was the most effective AED combination. The best response to AEDs used in monotherapy was observed at low dosage. This suggests that routine exposure to maximally tolerated AED doses may not be necessary to identify those patients with drug-resistant seizures who will have a beneficial response to therapy. Rather, responders to a given AED regimen may be identified with exposure to low AED doses, with careful evaluation of the response to subsequent titration to identify non-responders or those with exacerbation of seizure frequency at higher doses.

Simulating Clinical Trials With and Without Intracranial EEG Data

OBJECTIVE

It is currently unknown if knowledge of clinically silent (electrographic) seizures improves the statistical efficiency of clinical trials.

METHODS

Using data obtained from 10 patients with chronically implanted subdural electrodes over an average of 1 year, a Monte Carlo bootstrapping simulation study was performed to estimate the statistical power of running a clinical trial based on A) patient reported seizures with intracranial EEG (icEEG) confirmation, B) all patient reported events, or C) all icEEG confirmed seizures. A "drug" was modeled as having 10%, 20%, 30%, 40% and 50% efficacy in 1000 simulated trials each. Outcomes were represented as percentage of trials that achieved p<0.05 using Fisher Exact test for 50%-responder rates (RR50), and Wilcoxon Rank Sum test for median percentage change (MPC).

RESULTS

At each simulated drug strength, the MPC method showed higher power than RR50. As drug strength increased, statistical power increased. For all cases except RR50 with drug of 10% efficacy, using patient reported events (with or without icEEG confirmation) was not as statistically powerful as using all available intracranially confirmed seizures (p<0.001).

SIGNIFICANCE

This study demonstrated using simulation that additional accuracy in seizure detection using chronically implanted icEEG improves statistical power of clinical trials. Newer invasive and noninvasive seizure detection devices may have the potential to provide greater statistical efficiency, accelerate drug discovery and lower trial costs.

Pregabalin for essential tremor

BACKGROUND

Essential tremor is one of the most common movement disorders. Treatment primarily consists of pharmacological agents. While primidone and propranolol are well-established treatments in clinical practice, they may be ineffective in 25% to 55% of patients and can produce serious adverse events in a large percentage of them. For these reasons, it is worth evaluating the treatment alternatives for essential tremor. Some specialists have suggested that pregabalin could be a potentially useful agent, but there is uncertainty about its efficacy and safety.

OBJECTIVES

To assess the effects of pregabalin versus placebo or other treatment for essential tremor in adults.

SEARCH METHODS

We performed a systematic search without language restrictions to identify all relevant trials up to December 2015. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, NICE, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform (ICTRP). We handsearched grey literature and examined the reference lists of identified studies and reviews.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) of pregabalin versus placebo or any other treatments. We included studies in which the diagnosis of ET was made according to accepted and validated diagnostic criteria. We excluded studies conducted in patients presenting secondary forms of tremor or reporting only neurophysiological parameters to assess outcomes.

DATA COLLECTION AND ANALYSIS

Two reviewers independently collected and extracted data using a data collection form. We assessed the risk of bias of the body of evidence, and we used inverse variance methods to analyse continuous outcomes and measurement scales. We compared the mean difference between treatment groups, and we combined results for dichotomous outcomes using Mantel-Haenszel methods and risk differences We used Review Manager software for data management and analysis.

MAIN RESULTS

We only found one study eligible for this review (22 participants). We assessed the risk of bias for most domains as unclear. We graded the overall quality of evidence as very low. Compared to placebo, patients treated with pregabalin showed no significant improvement of motor tasks on the 36-point subscale of the Fahn-Tolosa-Marin Tremor Rating Scale (TRS) (MD -2.15 points; 95% CI -9.16 to 4.86) or on the 32-point functional abilities subscale of the TRS (MD -0.66 points; 95% CI -2.90 to 1.58).The limited evidence showed no difference in study withdrawal (Mantel-Haenszel RD -0.09; 95% CI -0.48 to 0.30) and presentation of adverse events between pregabalin and placebo (Mantel-Haenszel RD 0.18; 95% CI -0.13 to 0.50).

AUTHORS' CONCLUSIONS

The effects of pregabalin for treating essential tremor are uncertain because the quality of the evidence is very low. One small study did not highlight any effect of this treatment; however, the high risk of bias and the lack of other studies on this topic limit further conclusion.

The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential

Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development. Current therapeutic agents include drugs targeting L-type Ca(V)1.2 calcium channels, particularly 1,4-dihydropyridines, which are widely used in the treatment of hypertension. T-type (Ca(V)3) channels are a target of ethosuximide, widely used in absence epilepsy. The auxiliary subunit α2δ-1 is the therapeutic target of the gabapentinoid drugs, which are of value in certain epilepsies and chronic neuropathic pain. The limited use of intrathecal ziconotide, a peptide blocker of N-type (Ca(V)2.2) calcium channels, as a treatment of intractable pain, gives an indication that these channels represent excellent drug targets for various pain conditions. We describe how selectivity for different subtypes of calcium channels (e.g., Ca(V)1.2 and Ca(V)1.3 L-type channels) may be achieved in the future by exploiting differences between channel isoforms in terms of sequence and biophysical properties, variation in splicing in different target tissues, and differences in the properties of the target tissues themselves in terms of membrane potential or firing frequency. Thus, use-dependent blockers of the different isoforms could selectively block calcium channels in particular pathologies, such as nociceptive neurons in pain states or in epileptic brain circuits. Of important future potential are selective Ca(V)1.3 blockers for neuropsychiatric diseases, neuroprotection in Parkinson's disease, and resistant hypertension. In addition, selective or nonselective T-type channel blockers are considered potential therapeutic targets in epilepsy, pain, obesity, sleep, and anxiety. Use-dependent N-type calcium channel blockers are likely to be of therapeutic use in chronic pain conditions. Thus, more selective calcium channel blockers hold promise for therapeutic intervention.

The effects of antiepileptic drugs on cognitive functional magnetic resonance imaging

The cognitive dysfunction caused by antiepileptic drugs (AEDs) has been extensively described, although the mechanisms underlying such collateral effects are still poorly understood. The combination of functional magnetic resonance imaging (fMRI) studies with pharmacological intervention (pharmaco-MRI or ph-MRI) offers the opportunity to investigate the effect of drugs such as AEDs on brain activity, including cognitive tasks. Here we review the studies that investigated the effects of AEDs [topiramate (TPM), lamotrigine (LMT), carbamazepine (CBZ), pregabalin (PGB), valproate (VPA) and levetiracetam (LEV)] on cognitive fMRI tasks. Despite the scarcity of fMRI studies focusing on the impact of AEDs on cognitive task, the results of recent work have provided important information about specific drug-related changes of brain function.

Antiepileptic Drug Treatment in Children with Epilepsy

Most children with new-onset epilepsy achieve seizure freedom with appropriate antiepileptic drugs (AEDs). However, nearly 20 % will continue to have seizures despite AEDs, as either monotherapy or in combination. Despite the growing market of new molecules over the last 20 years, the proportion of drug-resistant epilepsies has not changed. In this review, we report the evidence of efficacy and safety based on phase III randomized controlled clinical trials (RCTs) of AEDs currently used in the paediatric population. We conducted a literature search using the PubMed database and the Cochrane Database of Systematic Reviews. We also analysed the RCTs of newer AEDs whose efficacy in adolescents and adults might suggest possible use in children. Most of the phase III trials on AEDs in children have major methodological limitations that considerably limit meaningful conclusions about comparative efficacy between old and new molecules. Since the efficacy of new drugs has only been reported versus placebo, the commonly held opinion that new and newer AEDs have a better safety profile than old ones does not appear to be supported by evidence. Despite limited solid evidence, pharmacological management has improved over the years as a consequence of increased awareness of some degree of specificity of treatment in relation to different epilepsy syndromes and attention to adverse events. Future research should be directed taking these factors, as well as the diversity of epilepsy, into consideration.

Cosmetic side effects of antiepileptic drugs in adults with epilepsy

OBJECTIVE

Cosmetic side effects (CSEs) such as weight gain and alopecia are common, undesirable effects associated with several AEDs. The objective of the study was to compare the CSE profiles in a large specialty practice-based sample of patients taking both older and newer AEDs.

METHODS

As part of the Columbia and Yale AED Database Project, we reviewed patient records including demographics, medical history, AED use, and side effects for 1903 adult patients (≥16years of age) newly started on an AED. Cosmetic side effects were determined by patient or physician report in the medical record and included acne, gingival hyperplasia, hair loss, hirsutism, and weight gain. We compared the overall rate of CSEs and intolerable CSEs (ICSEs-CSEs that led to dosage reduction or discontinuation) between different AEDs in both monotherapy and polytherapy.

RESULTS

Overall, CSEs occurred in 110/1903 (5.8%) patients and led to intolerability in 70/1903 (3.7%) patients. Weight gain was the most commonly reported CSE (68/1903, 3.6%) and led to intolerability in 63 (3.3%) patients. Alopecia was the second most common patient-reported CSE (36/1903, 1.9%) and was intolerable in 33/1903 (1.7%) patients. Risk factors for CSEs included female sex (7.0% vs. 4.3% in males; p<0.05) and any prior CSE (37% vs. 2.9% in patients without prior CSE; p<0.001). Significantly more CSEs were attributed to valproic acid (59/270; 21.9%; p<0.001) and pregabalin (14/143; 9.8%; p<0.001) than to all other AEDs. Significantly less CSEs were attributed to levetiracetam (7/524; 1.3%; p=0.002). Weight gain was most frequently associated with valproic acid (35/270; 13.0%; p<0.001) and pregabalin (12/143; 8.4%; p<0.001). Hair loss was most commonly reported among patients taking valproic acid (24/270; 8.9%; p<0.001). Finally, gingival hyperplasia was most commonly reported in patients taking phenytoin (10/404; 2.5%; p<0.001). Cosmetic side effects leading to dosage change or discontinuation occurred most frequently with pregabalin and valproic acid compared with all other AEDs (13.3 and 5.6% vs. 2.3%; p<0.001). For patients who had been on an AED in monotherapy (n=677), CSEs and ICSEs were still more likely to be attributed to valproic acid (30.2% and 17.1%, respectively) than to any other AED (both p<0.001).

SIGNIFICANCE

Weight gain and alopecia were the most common patient-reported CSEs in this study, and weight gain was the most likely cosmetic side effect to result in dosage adjustment or medication discontinuation. Particular attention should be paid to pregabalin, phenytoin, and valproic acid when considering cosmetic side effects. Female patients and patients who have had prior CSE(s) to AED(s) were more likely to report CSEs. Knowledge of specific CSE rates for each AED found in this study may be useful in clinical practice.

Drug-induced cerebellar ataxia: a systematic review

BACKGROUND AND OBJECTIVES

Cerebellar ataxia can be induced by a large number of drugs. We here conducted a systemic review of the drugs that can lead to cerebellar ataxia as an adverse drug reaction (ADR).

METHODS

We performed a systematic literature search in Pubmed (1966 to January 2014) and EMBASE (1988 to January 2014) to identify all of the drugs that can have ataxia as an ADR and to assess the frequency of drug-induced ataxia for individual drugs. Furthermore, we collected reports of drug-induced ataxia over the past 20 years in the Netherlands by querying a national register of ADRs.

RESULTS

Drug-induced ataxia was reported in association with 93 individual drugs (57 from the literature, 36 from the Dutch registry). The most common groups were antiepileptic drugs, benzodiazepines, and antineoplastics. For some, the number needed to harm was below 10. Ataxia was commonly reversible, but persistent symptoms were described with lithium and certain antineoplastics.

CONCLUSIONS

It is important to be aware of the possibility that ataxia might be drug-induced, and for some drugs the relative frequency of this particular ADR is high. In most patients, symptoms occur within days or weeks after the introduction of a new drug or an increase in dose. In general, ataxia tends to disappear after discontinuation of the drug, but chronic ataxia has been described for some drugs.

New generation antiepileptic drugs: what do they offer in terms of improved tolerability and safety?

Over the last two decades a total of 11 antiepileptic drugs (AEDs) have been introduced to the US market. Randomized, placebo-controlled trials have yielded information about each drug's efficacy, tolerability, and safety profile; however, few studies have compared the newer generation AEDs directly with the older generation. Comparative studies are not always straightforward in their interpretation, as many characteristics of drugs, both favorable and unfavorable, may not be highlighted by such studies. In general, findings from the literature suggest that the newer generation AEDs (including vigabatrin, felbamate, gabapentin, lamotrigine, tiagabine, topiramate, levetiracetam, oxcarbazepine, zonisamide, pregabalin, rufinamide, and lacosamide) enjoy both improved tolerability and safety compared with older agents such as phenobarbital, phenytoin, carbamazepine, and valproate. This is partially supported by some of the findings of the QSS and the TTA Committee of the American Academy of Neurology (AAN), whose review of four AEDs (gabapentin, lamotrigine, topiramate, and tiagabine) is discussed. Briefly, when compared with carbamazepine, lamotrigine was better tolerated; topiramate adverse events (AEs) were fairly comparable to carbamazepine and valproate; and tiagabine compared with placebo was associated with a higher discontinuation rate due to AEs. The findings of the SANAD trial are also presented; when administered to patients with partial epilepsy, carbamazepine was most likely to fail due to AEs, and lamotrigine and gabapentin were least likely to fail due to AEs. When administered to patients with idiopathic generalized epilepsy, topiramate was most frequently associated with AE-related discontinuation, followed by valproate; and while valproate was the most efficacious drug in this arm of the study, lamotrigine was more tolerable. What makes the SANAD study valuable and somewhat unique is its head-to-head comparison of one drug with another. Such comparative trials are overall lacking for new AEDs, although some conclusions can be drawn from the available data. In the end, however, AED selection must be based on individual patient and drug characteristics.

Pharmacotherapy for tonic-clonic seizures

INTRODUCTION

Occurrence of generalized tonic-clonic seizures (GTCS) is one of the most important risk factors of seizure-related complications and comorbidities in patients with epilepsy. Their prevention is therefore an important aspect of therapeutic management both in idiopathic generalized epilepsies and in focal epilepsies.

AREAS COVERED

It has been shown that the efficacy of antiepileptic drugs (AEDs) varies across epilepsy syndromes, with some AEDs efficacious against focal seizures with secondary GTCS (sGTCS) but aggravating primary GTCS (pGTCS). In patients with pGTCS, evidence-based data support the preferential use of valproic acid, lamotrigine, levetiracetam and topiramate. In patients with sGTCS, all AEDs approved in the treatment of focal epilepsies might be used.

EXPERT OPINION

Both in pGTCS and sGTCS, additional data are required, specifically to inform about the relative efficacy of AEDs in relation to each other. Although valproic acid might be the most efficacious drug in idiopathic generalized epilepsies, it should be avoided in women of childbearing age due to its safety profile. In patients with sGTCS, AEDs for which the impact on this seizure type has been formally evaluated and which have demonstrated greater efficacy than placebo might preferentially be used, such as lacosamide, perampanel and topiramate.

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.