Randomized, double-blind, placebo-controlled, phase II trial of gabapentin enacarbil for migraine prophylaxis. Gabapentin in the prophylaxis of migraine: a double-blind randomized placebo-controlled study. Efficacy of gabapentin in migraine prophylaxis. Outcome reporting in industry-sponsored trials of gabapentin for off-label use. [Effectiveness and safety of gabapentin in the preventive treatment of migraine]. Gabapentin: a promising drug for the treatment of uremic pruritus. Efficacy of gabapentin in treating chronic phantom limb and residual limb pain. Prolonged-release oxycodone enhances the effects of existing gabapentin therapy in painful diabetic neuropathy patients. Gabapentin therapy for pruritus in haemodialysis patients: a randomized, placebo-controlled, double-blind trial. Efficacy and tolerability of acetazolamide in migraine prophylaxis: a randomised placebo-controlled trial. Topiramate versus amitriptyline in migraine prevention: a 26-week, multicenter, randomized, double-blind, double-dummy, parallel-group noninferiority trial in adult migraineurs.
The objective of this article is to evaluate the efficacy and safety of gabapentin enacarbil (GEn) for migraine prophylaxis.
                In this randomized, double-blind, parallel-group study, patients with International Headache Society-defined migraine who met criteria suggesting the need for prophylactic therapy were randomized 2:1:2:2:1 to one of the following five groups, designated according to target daily dose of study medication during the 20-week treatment period: placebo, GEn 1200 mg, GEn 1800 mg, GEn 2400 mg, or GEn 3000 mg.
                The intent-to-treat population included 523 patients (n = 128 placebo, n = 66 GEn 1200 mg, n = 134 GEn 1800 mg, n = 133 GEn 2400 mg, n = 62 GEn 3000 mg). No statistically significant difference between active treatment (the average of 1800 mg and 2400 mg treatment groups) and placebo was found for change from baseline in the number of migraine headache days during the last four weeks of treatment prior to taper (the primary endpoint). Results of analyses of the primary endpoint using the per protocol population, analyses using imputation methods different from those of the primary analysis, and nonparametric analyses were consistent with the primary analysis in showing no difference between active treatment and placebo. The pattern of results was similar for the secondary efficacy endpoints. Pharmacokinetic data demonstrate that patients had adequate estimated exposure to GEn. The adverse event profile of GEn was consistent with that in previous studies.
                GEn did not significantly differ from placebo for migraine headache prophylaxis. A high placebo effect should be considered when interpreting these results. Gabapentin is an antiepileptic drug of new generation that increases brain GABA levels. We report the results of a three-month randomised double-blind placebo-controlled study on the effects of gabapentin in the prophylaxis of patients with migraine meeting the IHS criteria.
                We treated 63 patients suffering from migraine with or without aura. Patients treated their attack at home using symptomatic drugs and clinical assessment was recorded on a diary. After a washout of 8 week from any other prophylactic treatment, all patients were treated with 1200 mg/day of gabapentin; this is our therapeutic plan: 400 mg/day from 1st to 3rd day, 800 mg/day from 4th to 6th day and 1200 mg/day from 7th day.
                No patients withdrew, gabapentin was well tolerated; adverse events (somnolence, dizziness, tremor, fatigue and ataxia) generally were transient and mild to moderate in severity and in 13 patients (27%) only occurred. At the end of treatment, in such case, we reported a significative reduction of frequency and intensity of migraine in 30 patients treated with gabapentin.
                Our observations indicate that gabapentin is well tolerated by patients and that reduces headache frequency and use of symptomatic drugs in both groups. Gabapentin shows to have an effective therapeutic action in the prophylactic treatment of migraine. To compare gabapentin with placebo for use as a prophylactic agent in patients with migraine (with or without aura). STUDY DESIGN AND TREATMENT: After screening, a 4-week, single-blind, placebo baseline period was followed by a 12-week, double-blind, treatment period. The 12-week treatment period consisted of a 4-week titration phase and an 8-week stable-dosing phase. During the 4-week titration phase, patients were started on one 300-mg capsule of gabapentin or matching placebo. Patients were titrated weekly from 900 mg/day (end of week 1) to 2400 mg/day (end of week 4) and had to be receiving a stable dose of study medication by the end of the titration period. Study medication was to be given on a three-times-a-day dosing regimen.
                The study hypothesis was defined a priori as a lower 4-week migraine rate during the second stabilization period for the gabapentin-treated patients as compared with the placebo-treated patients. The analyses were performed with the 4-week migraine rate at baseline as a covariate and center as a blocking factor.
                At seven participating centers, 143 patients with migraine were randomized in a 2:1 ratio and received either gabapentin (n = 98) or matching placebo (n = 45). Thirty-three patients (24.1%) discontinued prematurely from the study, including 24 (24.5%) of 98 gabapentin-treated patients and 9 (20.0%) of 45 placebo-treated patients; the majority of patients discontinued due to adverse events (16 [16.3%] of 98 gabapentin-treated patients; 4 [8.9%] of 45 placebo-treated patients). Patients included in the analysis were evenly balanced for age, sex, race, weight, and height. The majority of these patients were white (80 [92.0%] of 87) and women (72 [82.8%] of 87), with a mean age of approximately 39.4 years and a history of migraine episodes for a mean of about 21 years. At the end of the 12-week treatment phase, the median 4-week migraine rate was 2.7 for the gabapentin-treated patients maintained on a stable dose of 2400 mg/day and 3.5 for the placebo-treated patients (P =.006), compared with 4.2 and 4.1, respectively, during the baseline period. Additionally, 26 (46.4%) of 56 patients receiving a stable dose of 2400 mg/day gabapentin and 5 (16.1%) of 31 patients receiving placebo showed at least a 50% reduction in the 4-week migraine rate (P =.008). The average number of days per 4 weeks with migraine was also statistically significant and favored gabapentin (P =.006) during stabilization period 2. The median change in 4-week headache rate was statistically significant as well (P =.013). The most frequently reported adverse events for both treatment groups were asthenia, dizziness, somnolence, and infection. Adverse events determined by the investigator to be associated with study drug resulted in patient withdrawal in 13 (13.3%) of 98 gabapentin-treated patients and 3 (6.7%) of 45 placebo-treated patients. Somnolence and dizziness accounted for many of the premature withdrawals among those taking gabapentin.
                Gabapentin is an effective prophylactic agent for patients with migraine. In addition, gabapentin appears generally well tolerated with mild to moderate somnolence and dizziness. There is good evidence of selective outcome reporting in published reports of randomized trials.
                We examined reporting practices for trials of gabapentin funded by Pfizer and Warner-Lambert's subsidiary, Parke-Davis (hereafter referred to as Pfizer and Parke-Davis) for off-label indications (prophylaxis against migraine and treatment of bipolar disorders, neuropathic pain, and nociceptive pain), comparing internal company documents with published reports.
                We identified 20 clinical trials for which internal documents were available from Pfizer and Parke-Davis; of these trials, 12 were reported in publications. For 8 of the 12 reported trials, the primary outcome defined in the published report differed from that described in the protocol. Sources of disagreement included the introduction of a new primary outcome (in the case of 6 trials), failure to distinguish between primary and secondary outcomes (2 trials), relegation of primary outcomes to secondary outcomes (2 trials), and failure to report one or more protocol-defined primary outcomes (5 trials). Trials that presented findings that were not significant (P > or = 0.05) for the protocol-defined primary outcome in the internal documents either were not reported in full or were reported with a changed primary outcome. The primary outcome was changed in the case of 5 of 8 published trials for which statistically significant differences favoring gabapentin were reported. Of the 21 primary outcomes described in the protocols of the published trials, 6 were not reported at all and 4 were reported as secondary outcomes. Of 28 primary outcomes described in the published reports, 12 were newly introduced.
                We identified selective outcome reporting for trials of off-label use of gabapentin. This practice threatens the validity of evidence for the effectiveness of off-label interventions.
                2009 Massachusetts Medical Society Migraine is a frequent and disabling pathological condition with important socioeconomic repercussions. Recent studies have explored the use of antiepileptic drugs in the prophylactic treatment of migraine. Preliminary studies have shown that gabapentin is a drug that is effective and well tolerated by patients. AIM. To evaluate the effectiveness and safety of gabapentin in the prophylactic treatment of migraine.
                A prospective, open, multicentre, random clinical study, carried out according to IHS criteria, which compares the effectiveness and safety of gabapentin in 1,200 mg/day and 2,000 mg/day doses as a preventive treatment for migraine over a 16 week period.
                Significant differences were found in patients treated with gabapentin, as compared with their basal state, in the following: a lower number of attacks (reduction in weeks 4, 10 and 16: 2.4 2.8, 2.9 2.9 and 3.1 2.9 attacks/month on a basal rate of 5.3 3.5 attacks/month), lower intensity (on a scale of 0 3 of increasing pain intensity: basal rate: 2.7 0.4, week 4: 1.8 0.9, week 10: 1.7 0.9, week 16: 1.4 1.0) and how long the pain lasts (basal rate 390 hours/month, week 4: 180 hours/month, week 10: 180 hours/month, week 16: 120 hours/month). No statistically significant differences were found between doses of 1,200 or 2,000 mg/day. Mild adverse effects were seen in 62 patients (37.8%): drowsiness (22.6%), asthenia (7.9%), dizziness (4.9%), abdominal pain (3.7%) and dazedness (3.7%). No serious adverse events occurred.
                Gabapentin can be considered an effective and safe drug in the preventive treatment of migraine. Despite advances made in treatment, uremic pruritus remains a common and distressing symptom in patients on hemodialysis (HD). Gabapentin is an effective drug in the management of neuropathic pain. Considering that neuropathic pain and pruritus share similar pathogenic mechanisms, we conducted this study to evaluate the efficacy of gabapentin in controlling uremic itch. In a double blind, placebo-controlled trial, 34 adult patients on maintenance HD were enrolled. The patients were assigned to receive four weeks of treatment with either gabapentin (400 mg) or placebo administered twice weekly after HD sessions. Pruritus scores were measured using a visual analogue scale and compared between the two groups.After four weeks of treatment, the mean decrease in pruritus score in gabapentin and placebo groups was 6.7 +/- 2.6 and 1.5 +/- 1.8, respectively (p< 0.001). None of the patients was forced to drop out of the study due to side effects of the treatment. Our study suggests that gabapentin is a safe and effective treatment for uremic itch. Twenty-four adults with phantom limb pain (PLP) and/or residual limb pain (RLP) participated in a double-blind crossover trial. Participants were randomly assigned to receive gabapentin or placebo and later crossed over to the other treatment, with a 5-week washout interval in which they did not receive medication. Gabapentin was titrated from 300 mg to the maximum dose of 3,600 mg. Measures of pain intensity, pain interference, depression, life satisfaction, and functioning were collected throughout the study. Analyses revealed no significant group differences in pre- to posttreatment change scores on any of the outcome measures. More than half of the participants reported a meaningful decrease in pain during the gabapentin phase compared with about one-fifth who reported a meaningful decrease in pain during the placebo phase. In this trial, gabapentin did not substantially affect pain. More research on the efficacy of gabapentin to treat chronic PLP and RLP is needed. Neuropathic pain remains one of the most challenging pain syndromes; under-diagnosed, poorly managed and associated with significant co-morbidity. With standard therapeutic treatments, responders rarely exceed 50% pain relief and the majority suffer from residual pain. Titration to optimum dose is often limited by dose-related adverse events.
                This randomized, double-blind, placebo-controlled study assessed the potential benefit of adding oxycodone (OxyContin tablets) to gabapentin. The primary endpoint was to evaluate the analgesic efficacy of co-administration of gabapentin and prolonged-release oxycodone, whilst also evaluating the use of escape medication, sleep quality and global assessment of pain.
                Three hundred and thirty eight patients with moderate to severe painful diabetic neuropathy despite receiving their maximum tolerated dose of gabapentin, had oral prolonged-release oxycodone or placebo tablets added to their therapy for up to 12 weeks.
                Oxycodone-gabapentin reduced pain score by 33% from baseline to end of treatment. The overall treatment effect was greater with oxycodone-gabapentin than with placebo-gabapentin (P = 0.007). Oxycodone-gabapentin also significantly improved pain relief vs gabapentin alone (P = 0.003). Oxycodone-gabapentin co-administration was associated with less escape medication use (P = 0.03) and fewer nights of disturbed sleep (P < 0.05). Discontinuations due to lack of therapeutic effect were much lower (14% vs 54%) with oxycodone-gabapentin. The commonly seen opiate-induced adverse events were not exacerbated by the combination of oxycodone and gabapentin.
                This study provides the first evidence that co-administration of prolonged-release oxycodone and existing gabapentin therapy has a clinically meaningful effect in painful diabetic neuropathy. Uraemic pruritus is a common and distressing symptom in patients on haemodialysis for chronic renal failure. Gabapentin is an anticonvulsant that alleviates neuropathic pain. We conducted a double-blind, placebo-controlled, crossover study to assess its effectiveness against renal itch.
                We enrolled in the trial 25 adult patients on haemodialysis who were asked to daily record the severity of their pruritus on a visual analogue scale. The patients were randomly assigned to receive gabapentin for 4 weeks followed by placebo for 4 weeks or the reverse sequence. Gabapentin or placebo were administered thrice weekly, at the end of haemodialysis sessions.
                The mean pruritus score of the cohort before the study was 8.4 +/- 0.94. After placebo intake, it decreased to 7.6 +/- 2.6 (P = 0.098). The score of four patients decreased by >50% following placebo. After gabapentin administration, the mean score decreased significantly, to 1.2 +/- 1.8 (P = 0.0001), although one patient's symptoms did not improve significantly. No patient dropped out of the study due to adverse effects from gabapentin.
                Our study shows that gabapentin is safe and effective for treating uraemic pruritus in haemodialysis patients. Our results also support the neuropathic hypothesis of uraemic pruritus. Familial hemiplegic migraine and episodic ataxia type 2 (EA2) are allelic disorders with distinct types of mutations in the CACNA1A gene. EA2 attacks are remarkably sensitive to acetazolamide, a carbonic anhydrase inhibitor. The effectiveness of acetazolamide in migraine prophylaxis is unknown.
                To evaluate the efficacy and the tolerability of acetazolamide in migraine prophylaxis.
                We compared daily oral 500 mg acetazolamide and placebo in patients with migraine in a multicentre, double-blind, randomised trial of 12 weeks duration after a run-in period of 4 weeks without treatment. Frequency of attacks at the last trial period of 4 weeks was the primary efficacy criterion. Secondary efficacy criteria were the frequency of attacks per 4 weeks, the severity and duration of attacks, the number of hours with migraine as well as the number of responders with more than 50% reduction in attack frequency.
                53 patients had been enrolled when the study was prematurely stopped because of a high number of withdrawals (34%), primarily linked to acetazolamide related side effects. Considering the primary and secondary efficacy criteria, among the 53 included patients (27 in the placebo group and 26 in the acetazolamide group), no difference between the 2 study groups could be demonstrated. The most frequent adverse events related to acetazolamide were paresthesias and asthenia.
                In this trial, migraine sufferers poorly tolerated acetazolamide given in an oral dose of 500 mg daily. No obvious prophylactic beneficial effect of acetazolamide appeared on migraine attacks. The primary objective of this study was to compare the efficacy and tolerability of topiramate and amitriptyline in the prophylaxis of episodic migraine headache.
                This was a 26-week, multicenter, randomized, double-blind, double-dummy, parallel-group noninferiority study. Adults with 3 to 12 migraines per month were randomized in a 1:1 ratio to receive an initial dose of 25 mg/d of either topiramate or amitriptyline, subsequently titrated to a maximum of 100 mg/d (or the maximum tolerated dose). The primary efficacy outcome was the change from prospective baseline in the mean monthly number of migraine episodes. Secondary efficacy variables included changes from the prospective baseline phase to the end of the double-blind phase in the mean monthly (28-day) rate of days with migraine, mean monthly rate of days with headache (migraine and nonmigraine), mean monthly rate of acute abortive medication use, mean monthly migraine duration, and mean monthly migraine severity. Additional secondary efficacy variables included changes in the mean monthly severity of migraine-associated symptoms (photophobia, phonophobia, and nausea), change in the mean monthly frequency f migraine-associated vomiting, and response rates (based on monthly migraine days and total headache days). The Migraine-Specific Quality of Life Questionnaire (MSQ) and the Weight Satisfaction Scale Questionnaire, which measures subjective satisfaction with current weight, were administered. Treatment-emergent adverse events (TEAEs) were monitored through the end of double-blind treatment.
                The intent-to-treat population included 331 subjects (172 topiramate, 159 amitriptyline; 84.9% female; 84.6% white; mean [SD] age, 38.8 [11.0] years; mean weight, 77.1 [20.1] kg) who provided at least 1 efficacy assessment. The least squares mean (LSM) change from baseline in the mean monthly number of migraine episodes was not significantly different between the topiramate and amitriptyline groups (-2.6 and -2.7, respectively; 95% CI, -0.6 to 0.7). There were no significant differences between treatment groups in any of the prespecified secondary outcome measures. Subjects receiving topiramate had a significantly greater improvement in mean functional disability scores during migraine attacks compared with amitriptyline (LSM change: -0.33 vs -0.19; 95% CI, -0.3 to 0.0; P = 0.040) and in the role function-restrictive, role function-preventive, and emotional function domains of the MSQ (P = 0.012, P = 0.014, and P = 0.029, respectively). Subjects receiving topiramate had a mean weight loss of 2.4 kg, compared with a mean weight gain of 2.4 kg in subjects receiving amitriptyline. Subjects in the topiramate group reported an overall improvement from baseline in weight satisfaction, whereas the amitriptyline group reported an overall deterioration in weight satisfaction (P < 0.001, topiramate vs amitriptyline). TEAEs of mild or moderate severity were reported in 118 subjects (66.7%) in the topiramate group and 112 subjects (66.3%) in the amitriptyline group. Among the most common TEAEs (reported in +/-5% of subjects during the double-blind phase) in the topiramate group were paresthesia (29.9%), fatigue (16.9%), somnolence (11.9%), hypoesthesia (10.7%), and nausea (10.2%). The most commonly reported TEAEs in the amitriptyline group were dry mouth (35.5%), fatigue (24.3%), somnolence (17.8%), weight increase (13.6%), dizziness (10.7%), and sinusitis (10.7%).
                In this noninferiority study, topiramate was at least as effective as amitriptyline in terms of reducing the rate of mean monthly migraine episodes and all prespecified secondary efficacy end points. Topiramate was associated with improvement in some quality-of-life indicators compared with amitriptyline and was associated with weight loss and improved weight satisfaction.
The pooled evidence derived from trials of gabapentin suggests that it is not efficacious for the prophylaxis of episodic migraine in adults. Since adverse events were common among the gabapentin-treated patients, it is advocated that gabapentin should not be used in routine clinical practice. Gabapentin enacarbil is not efficacious for the prophylaxis of episodic migraine in adults. There is no published evidence from controlled trials of pregabalin for the prophylaxis of episodic migraine in adults.