This study was designed to assess the efficacy and safety of pregabalin--a novel α₂-δ ligand with analgesic, anxiolytic, and anticonvulsant activity--for treating neuropathic pain in patients with post-herpetic neuralgia (PHN). Two hundred and thirty-eight patients were randomised into this multicentre, double-blind, placebo-controlled trial to receive 150 (n=81), 300 mg/day (n=76) pregabalin, or placebo (n=81) for 8 weeks. Among the exclusion criteria was failure to respond to previous treatment for PHN with gabapentin at doses 5:1200 mg/day. Endpoint mean pain scores were significantly reduced in patients receiving 150 or 300 mg/day pregabalin compared with placebo. Efficacy was observed as early as week 1 and was maintained throughout the study. Significantly more patients in both pregabalin groups (150 mg, 26%; 300 mg, 28%) were responders (>50% decrease in mean pain score from baseline to endpoint) than in the placebo group (10%). Additionally, by week 1 and for the study's duration, 150 and 300 mg/day pregabalin significantly reduced weekly mean sleep interference scores. More pregabalin-treated patients than placebo-treated patients reported that they were 'much improved' or 'very much improved'. Health-related quality-of-life (HRQoL) measurements using the SF-36 Health Survey demonstrated improvement in the mental health domain for both pregabalin dosages, and bodily pain and vitality domains were improved in the 300 mg/day group. The most frequent adverse events were dizziness, somnolence, peripheral oedema, headache, and dry mouth. Pregabalin efficaciously treated the neuropathic pain of PHN. Additionally, pregabalin was associated with decreased sleep interference and significant improvements in HRQoL measures. (PsycInfo Database Record (c) 2021 APA, all rights reserved)
<b>OBJECTIVE: </b>To evaluate the efficacy and safety of pregabalin in the treatment of postherpetic neuralgia (PHN).<b>METHODS: </b>The authors conducted a multicenter, parallel-group, double-blind, placebo-controlled, 8-week, randomized clinical trial in PHN, defined as pain for 3 or more months following herpes zoster rash healing. Patients (n = 173) were randomized to treatment with pregabalin or placebo. Patients randomized to pregabalin received either 600 mg/day (creatinine clearance > 60 mL/min) or 300 mg/day (creatinine clearance 30 to 60 mL/min). The primary efficacy measure was the mean of the last seven daily pain ratings. Secondary endpoints included additional pain ratings, sleep interference, quality of life, mood, and patient and clinician ratings of global improvement.<b>RESULTS: </b>Pregabalin-treated patients had greater decreases in pain than patients treated with placebo (endpoint mean scores 3.60 vs 5.29, p = 0.0001). Pain was significantly reduced in the pregabalin-treated patients after the first full day of treatment and throughout the study, and significant improvement on the McGill Pain Questionnaire total, sensory, and affective pain scores was also found. The proportions of patients with >or=30% and >or=50% decreases in mean pain scores were greater in the pregabalin than in the placebo group (63% vs 25% and 50% vs 20%, p = 0.001). Sleep also improved in patients treated with pregabalin compared to placebo (p = 0.0001). Both patients and clinicians were more likely to report global improvement with pregabalin than placebo (p = 0.001). Given the maximal dosage studied, pregabalin had acceptable tolerability compared to placebo despite a greater incidence of side effects, which were generally mild to moderate in intensity.<b>CONCLUSIONS: </b>Treatment of PHN with pregabalin is safe, efficacious in relieving pain and sleep interference, and associated with greater global improvement than treatment with placebo.
The efficacy and safety of sustained-release tramadol compared to placebo in the treatment of post-herpetic neuralgia were evaluated in a multicenter, randomized, double-blind, parallel-group study in 127 outpatients. Treatment was administrated for 6 weeks. The dose of tramadol could be increased from 100 mg/day to 400 mg/day (300 mg/day in patients more than 75 years old). Groups were compared on changes in pain intensity on a Visual Analogue Scale (VAS) between inclusion and the 6th week of treatment (covariance analysis as main analysis and repeated measures analysis as complementary analysis) in the per protocol (PP) population. The randomized population comprised 127 patients aged 35-85 years, mostly females (72.4%). Groups were comparable at inclusion both in the intent to treat (ITT) population (63 patients in the tramadol group and 62 patients in the placebo group) and in the PP population (53 patients in the tramadol group and 55 patients in the placebo group). Mean pain intensity on day 43 adjusted on day 1 (covariance analysis) was significantly lower in the tramadol group than in the placebo group in both the PP (P=0.0499), and the ITT (P=0.031) populations. The two groups significantly differed on change in pain intensity over time (repeated measures analysis) in the ITT population (P=0.012). The percentage of pain relief over the 6th week was significantly higher in the tramadol group than in the placebo group (P=0.017). During the 6th week, patients in the tramadol group required less rescue medication than patients in the placebo group (P=0.022). No significant difference was found between groups either in pain intensity on a 5-point Verbal Scale (VRS) or in quality of life measurements. Tramadol was administered at an average dosage of 275.5 (89.7) mg/day after a 1-week dose-adaptation period. Tramadol was well tolerated. No notable difference appeared between groups either in the percentage of patients with treatment-associated adverse events (TAAE) (29.7% in the tramadol group and 31.8% in the placebo group) or in the total number of TAAE (31 in the tramadol group and 28 in the placebo group).
Although opioids are commonly used to treat chronic neuropathic pain, there are limited data to guide their use. Few controlled trials have been performed, and many types of neuropathic pain remain unstudied. Adults with neuropathic pain that was refractory to treatment were randomly assigned to receive either high-strength or low-strength capsules of the potent μ-opioid agonist levorphanol for eight weeks under double-blind conditions. Intake was titrated by the patient to a maximum of 21 capsules of either strength per day. Outcome measures included the intensity of pain as recorded in a diary, the degree of pain relief, quality of life, psychological and cognitive function, the number of capsules taken daily, and blood levorphanol levels. Among the 81 patients (aged 32-91 yrs) exposed to the study drug, high-strength levorphanol capsules reduced pain by 36%, as compared with a 21% reduction in pain in the low-strength group. Affective distress and interference with functioning were reduced, and sleep was improved, but there were no differences between the high-strength group and the low-strength group in terms of these variables. The reduction in the intensity of neuropathic pain was significantly greater during treatment with higher doses of opioids than with lower doses. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
BACKGROUND: There are few repeated dose-controlled trials of N-methyl-d-aspartate glutamate receptor antagonists in patients with neuropathic pain. The authors sought to evaluate two low-affinity N-methyl-d-aspartate antagonists using a novel two-stage design.
METHODS: The authors studied patients with painful diabetic neuropathy (DN) and postherpetic neuralgia (PHN) in two crossover trials: (1) efficacy trial (dextromethorphan vs. memantine vs. active placebo [lorazepam]) and (2) dose-response trial of the preferred active drug in responders from the first study (0% vs. 25% vs. 50% vs. 100% of each patient's maximally tolerated dose). Pain intensity was measured on a 20-point scale.
RESULTS: Nineteen of 23 DN patients and 17 of 21 PHN patients completed the efficacy trial. Median doses for DN and PHN were 400 and 400 mg/day dextromethorphan, 55 and 35 mg/day memantine, and 1.8 and 1.2 mg/day lorazepam. In the efficacy trial, among patients with DN, dextromethorphan reduced pain intensity by a mean of 33% from baseline, memantine reduced pain intensity by a mean of 17%, and lorazepam reduced pain intensity by a mean of 16%; the proportions of subjects achieving greater than moderate pain relief were 68% with dextromethorphan, 47% with memantine, and 37% with lorazepam. Mean reductions in pain intensity in patients with PHN were 6% with dextromethorphan, 2% with memantine, and 0% with lorazepam. No comparison with placebo reached statistical significance in the efficacy trial. In the 10 DN subjects who responded to dextromethorphan, there was a significant dose-response effect on pain intensity (P = 0.035), with the highest dose significantly better than that of lorazepam (P = 0.03).
CONCLUSIONS: Dextromethorphan is effective in a dose-related fashion in selected patients with DN. This was not true of PHN, suggesting a difference in pain mechanisms. Selective approaches to pain-relevant N-methyl-d-aspartate receptors are warranted.
Compared the analgesic and cognitive effects of opioids with those of tricyclic antidepressants (TCA) and placebo in the treatment of postherpetic neuralgia (PHN). 76 32-90 yr olds with PHN were randomized in a double-blind, placebo-controlled, crossover trial. Each subject was scheduled to undergo 3 treatment periods (opioid, TCA, and placebo), approximately 8 wks in duration each. Doses were titrated to maximal relief or intolerable side effects. Outcome measures were pain intensity, pain relief, and cognitive function. Analyses included Ss who provided any pain ratings after having received at least a single dose of a study medication. 50 Ss completed 2 periods, and 44 Ss completed all three. Mean daily maintenance doses were morphine 91 mg or methadone 15 mg and nortriptyline 89 mg or desipramine 63 mg. Opioids and TCA reduced pain more than placebo with no appreciable effect on cognitive measure. The trend favoring opioids over TCA fell short of significance and reduction in pain with opioids did not correlate with that following TCA. Treatment with opioids and TCA resulted in greater pain relief compared with placebo. More patients completing all 3 treatments preferred opioids than TCA. Opioids effectively treat PHN without impairing cognition. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
Background: Nerve injury results in increases in spinal glutamate, which opens the NMDA ionophore channel, causing an influx of calcium. A glycine-binding site must be occupied for the channel to open. GV196771 is a selective antagonist of the glycine-binding site of the NMDA ionophore. Objective: To determine the efficacy of GV196771 in subjects with chronic neuropathic pain in a proof-of-concept study. Methods: With informed consent, 63 subjects (31 placebo, 32 GV196771) with neuropathic pain (diabetic neuropathy, postherpetic neuralgia, complex regional pain syndrome, or peripheral nerve injury), a visual analogue score averaging ≥30 mm during the screening period, and a well-defined primary area of mechanical allodynia were recruited for the study. A multicenter, randomized, double-blind, placebo-controlled, parallel-group study design was utilized. Subjects came to the research center for a total of five visits over a 21-day period, which consisted of a 14-day treatment period followed by a 7-day washout period. Spontaneous and evoked pain scores, mechanical sensory testing, quantitative sensory testing, Short Form McGill Pain Questionnaire, patient global satisfaction, and safety assessments were made during the study. Results: There was no significant effect of GV196771 on spontaneous or evoked pain, quantitative sensory testing, or patient global satisfaction. There was a significant effect of GV196771 on the area of dynamic and static allodynia on days 7 and 14. The overall incidence of adverse events during treatment was similar for GV196771 (56%) and placebo (71%). The incidence of drug-related adverse events during treatment was higher for placebo (42%) than GV196771 (28%). Conclusions: Although the glycine antagonists show anti-hyperalgesic action in animal models of neuropathic pain, GV196771 does not appear to be an effective treatment in subjects with chronic neuropathic pain. This may be due to insufficient penetration of GV196771 to central sites of action, differences between the human and animal glycine receptors, or differences between neuropathic pain in animal models and humans.
A multicentre double blind, randomised, placebo controlled 7-week study evaluated the efficacy and safety of gabapentin 1800 or 2400 mg/day in treating postherpetic neuralgia. Three hundred and thirty-four men and women aged at least 18 years (mean 73) received gabapentin 1800 or 2400 mg daily or placebo in three divided doses with a forced titration schedule. The primary outcome measure was change in average daily pain diary score (baseline week v final week). Secondary outcomes included mean weekly sleep interference score; Short Form-McGill Pain Questionnaire (SF-MPQ); Clinician and Patient Global Impression of Change (CGIC/PGIC); Short Form-36 Health Survey (SF-36). From week 1, pain scores showed a significantly greater improvement with gabapentin: the final difference v baseline was -34.5% for the 1800 mg dose, -34.4% for the 2400 mg dose compared with -15.7% for the placebo group. The difference vs. placebo was 18.8% for the 1800 mg dose (95% confidence interval 10.9-26.8%; P<0.01) and 18.7% for the 2400 mg dose (10.7-26.7%; P<0.01). Sleep interference diaries showed a similar pattern. There were significant differences in favour of gabapentin for number of patients reporting >50% reduction in their pain intensity, in the CGIC and PGIC, in the sensory and total scores of the SF-MPQ (both doses), in the visual analogue scale of pain of the SF-MPQ (2400 mg only) and in the vitality, bodily pain and mental health domains of the SF-36. Overall gabapentin was well tolerated. The most common adverse events were dizziness and somnolence, particularly during the titration phase. Thus, this study confirms the role of gabapentin as an efficacious and well-tolerated treatment for postherpetic neuralgia.
BACKGROUND: There is no effective treatment for intractable postherpetic neuralgia. Because there is evidence that postherpetic neuralgia has an inflammatory component, we assessed treatment with intrathecally administered methylprednisolone to reduce pain in patients with this disorder.
METHODS: We enrolled 277 patients who had had intractable postherpetic neuralgia for at least one year, 270 of whom were followed for two years. The patients were randomly assigned to receive intrathecal methylprednisolone and lidocaine (3 ml of 3 percent lidocaine with 60 mg of methylprednisolone acetate, 89 patients), lidocaine alone (3 ml of 3 percent lidocaine, 91 patients), or no treatment (90 patients) once per week for up to four weeks. Each weekly dose was injected into the lumbar intrathecal space. Pain was evaluated before randomization, at the end of the treatment period, and then four weeks, one year, and two years later. Samples of cerebrospinal fluid were obtained for measurement of interleukin-8 before and at the end of the treatment period.
RESULTS: There was minimal change in the degree of pain in the lidocaine-only and control groups during and after the treatment period. In the methylprednisolone-lidocaine group, the intensity and area of pain decreased, and the use of the nonsteroidal antiinflammatory drug diclofenac declined by more than 70 percent four weeks after the end of treatment. No complications related to intrathecal methylprednisolone were observed. Before treatment, the concentrations of interleukin-8 in the cerebrospinal fluid were inversely related to the duration of neuralgia in all the patients (r=-0.49, P<0.001). In the patients who received methylprednisolone, interleukin-8 concentrations decreased by 50 percent, and this decrease correlated with the duration of neuralgia and with the extent of global pain relief (P<0.001 for both comparisons).
CONCLUSIONS: The results of this trial indicate that the intrathecal administration of methylprednisolone is an effective treatment for postherpetic neuralgia.
BACKGROUND: Postherpetic neuralgia (PHN) is a vexing problem occurring in 10 to 20 percent of people with from herpes zoster (shingles). Anecdotal reports show that fluphenazine enhances the effects of amitriptyline for the treatment of PHN. The aim of this study was to determine, in a controlled manner, whether this was the case. METHODS: In a double-blind placebo-controlled study, 49 patients with PHN were randomly assigned to four treatment groups: Group 1, amitriptyline; Group 2, amitriptyline and fluphenazine; Group 3, fluphenazine; Group 4, a placebo. An active placebo was used to mimic the anticholinergic side effects of dry mouth. The study lasted 8 weeks, with weekly progress evaluations with use of visual analog scales (VAS), the McGill Pain Questionnaire (MPQ), and a side-effects scale. RESULTS: A statistically significant decrease was seen in pain in Groups 1 and 2, and no significant changes were seen in Groups 3 and 4. There was no significant difference when fluphenazine was added to amitriptyline. CONCLUSION: These data support the effectiveness of amitriptyline in treatment of PHN, but do not support the addition of fluphenazine.
This study was designed to assess the efficacy and safety of pregabalin--a novel α₂-δ ligand with analgesic, anxiolytic, and anticonvulsant activity--for treating neuropathic pain in patients with post-herpetic neuralgia (PHN). Two hundred and thirty-eight patients were randomised into this multicentre, double-blind, placebo-controlled trial to receive 150 (n=81), 300 mg/day (n=76) pregabalin, or placebo (n=81) for 8 weeks. Among the exclusion criteria was failure to respond to previous treatment for PHN with gabapentin at doses 5:1200 mg/day. Endpoint mean pain scores were significantly reduced in patients receiving 150 or 300 mg/day pregabalin compared with placebo. Efficacy was observed as early as week 1 and was maintained throughout the study. Significantly more patients in both pregabalin groups (150 mg, 26%; 300 mg, 28%) were responders (>50% decrease in mean pain score from baseline to endpoint) than in the placebo group (10%). Additionally, by week 1 and for the study's duration, 150 and 300 mg/day pregabalin significantly reduced weekly mean sleep interference scores. More pregabalin-treated patients than placebo-treated patients reported that they were 'much improved' or 'very much improved'. Health-related quality-of-life (HRQoL) measurements using the SF-36 Health Survey demonstrated improvement in the mental health domain for both pregabalin dosages, and bodily pain and vitality domains were improved in the 300 mg/day group. The most frequent adverse events were dizziness, somnolence, peripheral oedema, headache, and dry mouth. Pregabalin efficaciously treated the neuropathic pain of PHN. Additionally, pregabalin was associated with decreased sleep interference and significant improvements in HRQoL measures. (PsycInfo Database Record (c) 2021 APA, all rights reserved)
