Efficacy and safety of ezogabine/retigabine as adjunctive therapy to specified single antiepileptic medications in an open-label study of adults with partial-onset seizures.

PURPOSE: To assess efficacy/tolerability of ezogabine (EZG)/retigabine (RTG) in combination with specified monotherapy antiepileptic drug (AED) treatments in adults with uncontrolled partial-onset seizures using a flexible dosing regimen. METHODS: NCT01227902 was an open-label, uncontrolled study of flexibly dosed EZG/RTG. Adults with partial-onset seizures must have been taking either carbamazepine/oxcarbazepine (CBZ/OXC), lamotrigine (LTG), levetiracetam (LEV), or valproic acid (VPA). The study comprised a screening/baseline phase, a 4-week titration phase (initiation on 150mg/day [50mg three times daily (TID)] with weekly increases of 150mg/day [50mg TID] over 4 weeks to 600mg/day), and a flexible dose evaluation (FDE) phase (optional weekly dose changes of 50-150mg/day, to an optimal daily dosage [300-1200mg/day]). The primary efficacy endpoint was percentage of patients experiencing a ≥50% reduction from baseline in partial seizure frequency (responder rate) during the treatment phase (titration and FDE phases). Safety and tolerability were also assessed. RESULTS: Patients (N=203) were enrolled and received ≥1 dose of EZG/RTG. The dose of EZG/RTG prescribed most frequently during the treatment phase was 600mg/day for all AED groups. Responder rates during the treatment phase were: 40.0% (CBZ/OXC), 32.0% (LTG), 50.0% (LEV), and 56.9% (VPA). Treatment-emergent adverse events occurred in 82% (CBZ/OXC), 76% (LTG), 73% (LEV), and 67% (VPA) of patients; most were of mild-to-moderate intensity. CONCLUSIONS: EZG/RTG was effective as adjunctive therapy to CBZ/OXC, LTG, LEV, and VPA, using a flexible dosing regimen, in adults with partial-onset seizures; safety and tolerability were consistent with that previously observed.

A novel design for a dose finding, safety, and drug interaction study of an antiepileptic drug (retigabine) in early clinical development.

OBJECTIVE: To obtain information on the acceptable doses of the antiepileptic drug (AED) retigabine (RTG), the maximum tolerated dose (MTD), drug interactions, safety and tolerability, and preliminary evidence of efficacy when administered as adjunctive therapy and as monotherapy. MATERIALS: Study 202 was an open-label, add-on study in patients with partial or generalized epilepsy treated with valproic acid (VPA), carbamazepine (CBZ), phenytoin (PHT), or topiramate (TPM) as monotherapy. Following baseline assessments, patients entered a dose titration phase of 28 – 56 days. The initial daily RTG dose was 100 or 200 mg (2 or 3 × daily). The RTG dose was increased every 1 - 2 weeks by 50 - 200 mg to a maximum of 1,600 mg/day. Once the RTG MTD had been attained, patients entered a 14-day maintenance period. Following this, the patient's background AED dose could be reduced, with the possibility of achieving RTG monotherapy. The final dosing regimen attained was maintained for an additional 14 days. Patients who completed study 202 could choose to continue treatment with RTG (with or without other AEDs) in study 208, the long-term extension of study 202. Safety assessments included adverse event (AE) monitoring, clinical laboratory evaluations, electrocardiograms, and physical and neurologic examinations. Patients' seizure diaries to assess the frequency and type of seizures, the percentage change in seizure rate, and the responder rate (>= 50% reduction in seizure rate from baseline) were evaluated. RESULTS: 60 patients (mean age 37.2, range 16 - 64 years) were enrolled in study 202, and 47 (78%) continued treatment with RTG in the extension study (208). In study 202, the most commonly reported AEs were: dizziness (53%), asthenia (42%), somnolence (33%), nausea (27%), speech disorder (27%), and tremor (27%). In the extension study, AEs were similar and included dizziness, somnolence, diplopia, feeling "drunk", confusion, fatigue, and dysarthria. The median percent reductions in 28-day seizure rate, relative to baseline in Studies 202 and 208, were ~ 20% and 47%, respectively. RTG did not alter the pharmacokinetics of the four monotherapy AEDs investigated. CBZ and PHT increased RTG clearance by 27% and 36%, respectively, whereas TPM and VPA had no effect on RTG clearance. CONCLUSIONS: Studies 202 and 208 provided critical information on RTG safety and tolerability, and reductions in seizure rates towards the design and conduct of subsequent pivotal clinical trials. Likewise, information regarding the appropriate dosage of RTG with VPA, CBZ, PHT, or TPM was obtained, which permitted the subsequent pivotal trials to be performed appropriately. *Currently at Shire Pharmaceuticals, Behavioral Health Business Unit, Wayne, PA, USA **Currently at University of Pennsylvania, Department of Neurology, Philadelphia, PA, USA.

Adjunctive use of ezogabine/retigabine with either traditional sodium channel blocking antiepileptic drugs (AEDs) or AEDs with other mechanisms of action: Evaluation of efficacy and tolerability.

Integrated data from three double-blind, randomized, placebo-controlled trials were analyzed to evaluate the efficacy and tolerability of ezogabine (EZG; US adopted name)/retigabine (RTG; international non-proprietary name) when used in combination with ≥1 sodium channel blocking antiepileptic drug (AED), ≥1 non-sodium channel blocking AED, or ≥1 AED from both the sodium channel and non-sodium channel mechanistic groups. Efficacy and tolerability appeared to be similar across all three groups of patients.

Safety and tolerability of different titration rates of retigabine (ezogabine) in patients with partial-onset seizures.

Retigabine (RTG; international nonproprietary name)/ezogabine (EZG; US adopted name) is an antiepileptic drug (AED) that prolongs neuronal voltage-gated potassium-channel KCNQ2-5 (Kv 7.2-7.5) opening. This double-blind study evaluated different RTG/EZG dose-titration rates. Patients (N=73) with partial-onset seizures receiving concomitant AEDs were randomized to one of three titration groups, all of which were initiated at RTG/EZG 300mg/day divided into three equal doses. Fast-, medium-, and slow-titration groups received dose increments of 150mg/day every 2, 4, and 7 days, respectively, achieving the target dose of 1200mg/day after 13, 25, and 43 days, respectively. Safety assessments were performed throughout. Discontinuation rates due to treatment-emergent adverse events (TEAEs) were numerically higher in the fast- (10/23) and medium- (7/22) titration groups than in the slow-titration group (3/23) but statistical significance was achieved only for the high-titration group compared with the low-titration group (p=0.024). Stratified analysis, with concomitant AEDs divided into enzyme inducers (carbamazepine, phenytoin, oxcarbazepine) or noninducers, showed that the risk of discontinuation due primarily to TEAEs was significantly higher in the fast- (p=0.010) but not in the medium-titration group (p=0.078) when compared with the slow-titration group. Overall, the slow-titration rate appeared to be best tolerated and was used in further efficacy and safety studies with RTG/EZG.

Investigation of the impact of urine handling procedures on interpretation of urinalysis findings and product safety in subjects treated with ezogabine.

BACKGROUND: Ezogabine (also known by the international nonproprietary name of retigabine) is an antiepileptic drug codeveloped and comarketed by Valeant Pharmaceuticals North America and GlaxoSmithKline, which reduces neuronal excitability by enhancing the activity of potassium channels and has the potential to have effects on the urinary system through a pharmacologic action on bladder smooth muscle. In a single post-herpetic neuralgia trial, but not in an extensive epilepsy development program, proteinuria was unexpectedly reported in patients receiving ezogabine. Consequently, investigations were conducted to determine whether the reported proteinuria represented a true or false-positive finding. METHODS: Patients receiving ezogabine 900-1200 mg/day in an open-label extension (Study 303) of a Phase III epilepsy trial voluntarily provided urine samples. Fresh samples were analyzed immediately at the study site, and stabilized aliquots were analyzed 1-3 days after collection at two central laboratories. In an open-label study in healthy volunteers receiving ezogabine 600-900 mg/day (Study RTG114137), urine samples were analyzed fresh (<2 hours after collection) and, using two different stabilizers and storage at room temperature, after 24 and 72 hours. Fluid intake was restricted prior to one sample point. Albumin:creatinine ratios were assessed in both studies. RESULTS: In Study 303, there was notable variation in clarity, color, and proteinuria between fresh and stored urine samples, and between samples analyzed at different laboratories. In RTG114137, reporting rates of proteinuria were elevated following storage using one stabilizer, and the frequency of color change from fresh to stored samples differed between the stabilizers and between 24 and 72 hours with one stabilizer. Following fluid restriction, proteinuria rates were elevated with both stabilizers. Poor tolerability of ezogabine 750-900 mg/day resulted in limited titration beyond 750 mg/day and early termination of RTG114137. CONCLUSION: Hydration status, interval between urine collection and analysis, and the type of stabilizer used are all factors that may lead to false-positive proteinuria findings in patients receiving ezogabine and should be borne in mind if abnormalities are reported.

Retigabine as adjunctive therapy in adults with partial-onset seizures: integrated analysis of three pivotal controlled trials.

We assessed the efficacy and tolerability of retigabine (RTG; international non-proprietary name)/ezogabine (EZG; US adopted name) as adjunctive therapy in adults with partial-onset seizures in an integrated analysis of three trials. Studies 205, 301 (NCT00232596), and 302 (NCT00235755) were randomized, double-blind, placebo-controlled studies in adults having ≥4 partial-onset seizures per 28 days and receiving 1-3 antiepileptic drugs with/without vagus nerve stimulator. Patients underwent titration to RTG/EZG 600, 900, or 1200 mg/day or to placebo followed by 8 or 12 weeks maintenance. For efficacy analyses, placebo was compared with RTG/EZG 600 and 900 mg/day in Studies 205 and 302, and RTG/EZG 1200 mg/day in Studies 205 and 301. Responder rates (≥50% reduction in baseline seizure frequency) were 35% and 45% for RTG/EZG 600 and 900 mg/day, respectively (placebo=21%; p<0.001), and 50% for RTG/EZG 1200 mg/day (placebo=24%, p<0.001). Reductions in 28-day total partial-seizure frequency (medians: placebo=14%; 600 mg/day=26%, p=0.003; 900 mg/day=37%, p<0.001; placebo=15%; 1200 mg/day=39%, p<0.001) were significantly greater with all RTG/EZG doses vs. placebo from baseline to the double-blind phase, and similarly during the maintenance phase. The most commonly reported (>10%) treatment-emergent adverse events were dizziness, somnolence, headache, and fatigue. RTG/EZG demonstrated efficacy and was generally tolerated as adjunctive therapy in adults with partial-onset seizures in this integrated analysis.

The urinary safety profile and secondary renal effects of retigabine (ezogabine): a first-in-class antiepileptic drug that targets KCNQ (K(v)7) potassium channels.

Retigabine (RTG; international nonproprietary name)/ezogabine (EZG; North American adopted name), a first-in-class antiepileptic drug (AED) that reduces neuronal excitability primarily by enhancing the activity of KCNQ2/3 (K(v)7.2/7.3) potassium channels, has recently been approved by the European Medicines Agency and the U.S. Food and Drug Administration as adjunctive therapy in adults with partial-onset seizures. Much of the RTG/EZG safety profile will be familiar to health care professionals who are experienced with the clinical use of AEDs. RTG/EZG, as a potassium channel opener, also has a pharmacologic effect on smooth muscle of the urinary bladder. Consequently, the adverse event (AE) profile of RTG/EZG includes a potential risk of effects on the urinary system. This review summarizes the urinary safety profile and any secondary renal effects of RTG/EZG using data from patients in the pivotal controlled trials and the overall phase 2/3 clinical development program. Urinary AEs were reported more frequently in patients receiving RTG/EZG compared with placebo, although most patients were able to continue with treatment. Specifically, there is an increased risk of urinary retention with RTG/EZG, with urinary hesitation representing the most frequently reported urinary retention-related AE. Potential secondary renal effects, which may be caused by an inability to empty the bladder, were evaluated. Crystals with a bilirubin-like appearance were detected in the urine of patients receiving RTG/EZG. Although investigations indicated that these crystals were not bilirubin, their composition remains undetermined. There was no causal association with urinary tract infections, and nephrolithiasis was uncommon. The reported clinical effects of RTG/EZG are consistent with its documented effects on bladder smooth muscle in preclinical studies. RTG/EZG should be used with caution in patients at risk of urinary retention.

Randomized polysomnography study of gabapentin enacarbil in subjects with restless legs syndrome.

We assessed the efficacy and tolerability of gabapentin enacarbil in the treatment of moderate to severe primary restless legs syndrome and associated sleep disturbance. This was a multicenter, randomized, double-blind, placebo-controlled, 2-period crossover polysomnography study of gabapentin enacarbil 1200 mg or placebo taken once daily. Subjects were randomized 1:1 to a sequence of gabapentin enacarbil:placebo or placebo:gabapentin enacarbil, receiving each treatment for 4 weeks. The primary end point was the mean change from baseline at weeks 4 and 10 (4/10) last observation carried forward in wake time during sleep. The key secondary end point was the mean change from baseline at weeks 4/10 last observation carried forward in periodic limb movements associated with arousal per hour of sleep. Tolerability assessments included adverse events. One hundred thirty-six subjects were randomized (gabapentin enacarbil:placebo, 67; placebo:gabapentin enacarbil, 69), and 114 (gabapentin enacarbil:placebo, 53; placebo:gabapentin enacarbil, 61) completed the study. Gabapentin enacarbil 1200 mg significantly reduced wake time during sleep (mean change from baseline [adjusted mean treatment difference]: -26.0 minutes; P < .0001) and periodic limb movements associated with arousal per hour of sleep (adjusted mean treatment difference: -3.1 periodic limb movements with arousal/hour; P = .002) compared with placebo at weeks 4/10 last observation carried forward. The most commonly reported adverse events were dizziness (gabapentin enacarbil 20%, placebo 2%) and somnolence (gabapentin enacarbil 13%, placebo 2%). Gabapentin enacarbil 1200 mg once daily significantly reduces restless legs syndrome-associated sleep disturbance and periodic limb movements associated with arousal per hour of sleep and is generally well tolerated in adults with moderate to severe primary restless legs syndrome.

Two double-blind, multicenter, randomized, placebo-controlled, single-dose studies of sumatriptan/naproxen sodium in the acute treatment of migraine: function, productivity, and satisfaction outcomes.

OBJECTIVE: To describe return to normal function, productivity, and satisfaction of patients with moderate or severe migraine attacks treated with combined sumatriptan/naproxen sodium, sumatriptan alone, naproxen sodium alone, or placebo. PATIENTS, DESIGN, AND SETTING: Patients in 2 identical, US, phase 3, randomized, double-blind, parallel-group, placebo-controlled, single-dose, multicenter studies treated a single moderate or severe migraine attack with sumatriptan/naproxen sodium (85 mg sumatriptan formulated with RT Technology and 500 mg naproxen sodium in a single-tablet formulation), sumatriptan, naproxen sodium, or placebo. MAIN OUTCOME MEASURES: Ability to function (not impaired, mildly impaired, severely impaired, or required bed rest) was collected in diary cards completed immediately prior to treatment, every 30 minutes for the first 2 hours, and hourly from 2 to 24 hours while awake. Patients completed the Productivity Assessment Questionnaire (PAQ) 24 hours after study drug administration. The Patient Perception of Migraine Questionnaire (PPMQ) was administered at screening and 24 hours post treatment to capture patient satisfaction. RESULTS: Compared with the other groups, the sumatriptan/naproxen sodium group reported significantly higher levels of normal or mildly impaired functioning as early as 2 and 4 hours after dosing. They also demonstrated greater reductions in workplace productivity loss compared with placebo in both studies, and were consistently more satisfied with their treatment compared with patients in other treatment groups and compared with their usual medications. CONCLUSIONS: Treatment with sumatriptan/naproxen sodium allowed significantly more subjects to return to normal or mildly impaired functioning more quickly, and sumatriptan/naproxen sodium patients were significantly more satisfied with their treatment compared with other treatment groups. Overall productivity loss was significantly reduced following use of sumatriptan/naproxen sodium.

The experiences of midlife women with migraines.

PURPOSE: To describe the experiences of midlife women with migraines. DESIGN AND METHODS: Qualitative data were collected in two consecutive studies, using open-ended interviews, focus groups, and online discussion boards. Interpretive methods were used for analysis. FINDINGS: Three patterns were identified: Changing Headache Patterns; Predicting, Preventing, and Controlling Headaches; and Keeping on the Move. These patterns indicated how women's headaches changed over time, how headaches were envisioned within the context of their lives, what strategies were used to meet work and home responsibilities, and how women controlled their headaches while maintaining a sense of perspective. CONCLUSIONS: Many midlife women with migraines receive inadequate or inappropriate treatment, and better dissemination of current diagnostic and treatment guidelines is necessary. Ongoing research is needed to increase understanding of how this problem affects midlife women's lives and of what interventions might prevent or alleviate migraine discomfort.