Postherpetic Neuralgia

September 10, 2012

NeurogesX reported results from a phase II trial of NGX-1998 for the treatment of postherpetic neuralgia (PHN). This multicenter, placebo-controlled, double-blind study enrolled patients who had experienced pain for at least six months following healing of a herpes zoster lesion and had a Mean Numeric Pain Rating Scale (NPRS) score between 4 and 9, inclusive. Subjects were divided into three arms: NGX-1998 capsaicin 20% solution, NGX-1998 capsaicin 10% solution or placebo. Results indicated that with a single, five-minute treatment with NGX-1998, subjects experienced pain relief for as long as three months. NGX-1998 showed a greater magnitude of response on the pain intensity scale correlating with the concentration of the formulation: 20%>10%>placebo. In addition, it was determined that no topical anesthetic pre-treatment was required for treatment with NGX-1998. The drug was well tolerated. Subjects experienced similar adverse events as those in the placebo arm. Based on these data, NeurogesX plans to enable a phase III trial in neuropathic pain.

July 30, 2012

Depomed reported results from a phase III trial of Gralise for the treatment of pain in patients with postherpetic neuralgia (PHN). This multi-center, double-blind, randomized, placebo-controlled study enrolled 452 patients with a pain intensity score of at least four on the 11-point Numerical Rating Scale (NRS) at screening.Subjects received once-daily Gralise (gabapentin 1800mg) or placebo for 11 weeks. Results showed a significant reduction in the intensity of pain (-2.12) in Gralise subjects’ average daily pain intensity compared with placebo patients (-1.63; p=0.013). This difference from placebo was statistically significant after just one week. The drug was well tolerated. The most frequent adverse events were dizziness, headache and nausea. Depomed did not comment on their plans for Gralise.

December 26, 2011

Aestus Therapeutics issued results from a phase II trial of ATx08-001 for the treatment of post-herpetic neuralgia. This randomized, double-blind, placebo-controlled, multi-center study evaluated two doses of ATx08-001 (2.5 and 7.5 mg) over eight days. Both doses of ATx08-001 showed a statistically significant reduction in the Mean Pain Intensity Score (MPIS) after one week of treatment when compared to standard of care. The treatment was well tolerated.

September 28, 2009

XenoPort and GlaxoSmithKline announced top-line results from a phase IIb trial of gabapentin enacarbil for post-herpetic neuralgia. This 14-week, double-blind, placebo-controlled study enrolled 376 subjects with PHN who had been experiencing pain for at least three months following healing of the herpes zoster skin rash. The subjects were randomized to receive placebo, 1200, 2400 or 3600 mg/day of gabapentin enacarbil dosed twice a day. The primary endpoint, the change from baseline to the end of maintenance treatment in the 24-hour average pain intensity score, was reached with statistical significance over placebo in all gabapentin enacarbil dose groups: 1200 mg/day (p&equiv'0.013), 2400 mg/day (p≡0.029) and 3600 mg/day (p≡0.002).Treatment was generally well tolerated at all doses.

September 10, 2007

NeurogesX issued positive top-line results from a phase III trial of Transacin for the treatment of postherpetic neuralgia (PHN). This randomized, double-blind, controlled trial, dubbed C117, enrolled 416 subjects in the US and Canada. The trial was designed to evaluate the effect of a single, 60 minute treatment with Transacin or a low-concentration control patch applied directly to the site of pain. After one hour, the patch was removed and treatment response was evaluated during a 12-week study period. The primary endpoint, reduction in pain from baseline to study weeks 2-8, reached statistical significance over control. Treatment with Transacin showed a 32% reduction in pain from baseline as compared to a 24% reduction in pain for the control patch (p=0.01). The key secondary endpoint, reduction in pain from baseline to study weeks 2-12, also reached significance over control (p<0.02). All other secondary endpoints, including 30% and 50% responder analyses, were met as well. Based on positive phase III results NeurogesX plans to file a MAA in Europe later in 2007 and a NDA with the FDA in the second half of 2008.

July 16, 2007

DepoMed reported negative results from a phase III trial of Gabapentin GR for the treatment of postherpetic neuralgia (PHN). This randomized, double-blind, placebo-controlled trial enrolled 407 subjects who were placed into one of three treatment groups to receive Gabapentin GR once-daily, Gabapentin GR twice-daily (each 1800 mg/day) or placebo for 10 weeks. The primary endpoint was the reduction in average daily pain scores from baseline to endpoint with Gabapentin GR compared to placebo. Statistical significance was not reached for either active treatment group. The average daily reductions were 1.83 (once-daily), 1.72 (twice-daily) and 1.43 (placebo). However, statistical significance was achieved in all the secondary endpoints, including Clinical Global Impression of Change (p less than 0.001) and Patient Global Impression of Change (p=0.009). DepoMed plans to fully evaluate the data in order to determine a future course of action.

October 23, 2006

NeurogesX reported positive results from a phase III trial of Transacin for the treatment of post-herpetic neuralgia. This trial enrolled 402 subjects who were randomized to receive a single, one-hour treatment with Transacin or a matching, low-concentration capsaicin control patch. Pain intensity was recorded daily by the subjects for 12 weeks, using the Numeric Pain Rating Scale. The primary endpoint of the trial was met, with subjects in the treatment group reporting a statistically significant reduction in pain after a one hour infusion with Transacin (p=0.001). This reduction in pain was noted during the first week following treatment (p=0.04) and was maintained throughout the 12-week study period. NeurogesX plans to submit a MAA to the EMEA in early 2007 and a NDA to the FDA in mid-2008.

Neurologix announced positive one year results from a phase I trial of NLX-P101, a gene therapy treatment for Parkinson's disease. This open label, dose escalating, unilateral trial enrolled 12 subjects who were placed into one of three dose-escalating cohorts. Treatment was well tolerated, with no serious adverse events reported. Efficacy results revealed that all subjects demonstrated at least a 25% improvement in the Unified Parkinson's Disease Rating Scale (UPDRS) compared to baseline (p < 0.005). Of the 12, nine had a 37% improvement and five had a 40-65% improvement. Based on the results Neurologix plans to infuse both sides of the brain in upcoming phase II trials.

July 3, 2006

Depomed has issued positive results of a pair of trials of gabapentin GR for the treatment of post-herpetic neuralgia (PHN). These open-label studies enrolled 33 healthy male volunteers in a pharmacokinetic study and a dose proportionality study. In the pharmacokinetic study, 15 subjects received 600 mg of either gabapentin GR or an immediate release formulation of the drug with a standardized meal, and trial data indicated similar single-dose bioavailability. In the dose-proportionality study, 19 subjects received escalating single doses of gabapentin GR (600 mg, 1200 mg, 1800 mg or 2400 mg). Trial data indicated a nearly-linear 24 hour absorption profile for the four doses (35,698 ng*hr/ml, 63,209 ng*hr/ml, 90,893 ng*hr/ml, and 108,572 ng*hr/ml, respectively). At that time, Depomed's phase III trial of the drug for the treatment of PHN was ongoing.

April 11, 2005

XenoPort has reported positive results of a phase IIa trial of their transported gabapentin prodrug XP13512, for the treatment of post-herpetic neuralgia (PHN). Study data indicated that the drug produced a statistically significant reduction in pain severity over the final 7 days of treatment vs. placebo (p=0.032), the primary endpoint. The drug also produced significant improvement in secondary endpoints, including symptom severity score on the Short-Form McGill Pain Questionnaire, sleep interference, total pain score at the end of treatment, and Patient and Investigator Global Impression of Change. Pharmacokinetic analysis indicated that the prodrug produced a higher absolute steady-state plasma concentration than gabapentin alone, despite a 33% reduction in total equivalent gabapentin dose. This double-blind, placebo-controlled, multicenter study enrolled 101 PHN patients across 18 US sites, who all received 7 days of treatment with 600 mg. thrice daily gabapentin, followed by randomization to either 1,200 mg twice daily XP13512 or placebo for 14 days.

March 14, 2005

Renovis announced the results of a phase II study of REN-1654, their investigational TNF-alpha release inhibitor for the treatment of post-herpetic neuralgia (PHN). Study data failed to meet their primary efficacy endpoint, with mean reduction in daily spontaneous pain severity ratings at three weeks of -0.60 points for the low dose drug group, -0.57 for the high dose drug group, and -0.90 for the placebo group (no significant difference between values). The drug was generally well tolerated, and incidence of serious adverse events was similar between the drug and placebo. This double-blinded, placebo-controlled, multi-center study enrolled 94 patients with a history of herpes zoster (shingles) followed by persistent pain due to PHN. Following a 1-week washout/baseline period, subjects were randomized to receive one of two doses of REN-1654 (30 mg or 100 mg) or placebo once daily for 21 days. Renovis announced plans to discontinue development of the drug for PHN, but stated that these data would not affect an ongoing phase II trial of the drug for the treatment of sciatica.

January 19, 2004

XenoPort reported positive results from a phase I trial investigating XP13512, a transported prodrug of gabapentin. Results demonstrated that XP13512 was rapidly absorbed and was converted to gabapentin. Reported adverse effects were mild and consistent with those previously reported for the drug Neurontin. At the highest dose tested, mean gabapentin exposure after treatment was approximately 2.5 times higher than that of Neurontin. In addition, data showed that XP13512 provided substantially higher gabapentin exposure than equimolar Neurontin in all subjects. The randomized, placebo-controlled, double-blind study was designed to test the safety, tolerability and pharmacokinetics of XP13512 in healthy adults. Subjects were given five ascending single doses of an immediate-release formulation.

March 24, 2003

Endo Pharmaceuticals reported positive results from a series of phase IV trials investigating Lidoderm (lidocaine patch 5%) for the treatment of pain. The first study a randomized, open-label, multicenter, two-week pilot study designed to assess the impact of Lidoderm in subjects with postherpetic neuralgia (PHN), diabetic neuropathy (DN), or low back pain. Results showed that addition of Lidoderm reduced most pain interference in the PHN group and all interference in the DN and back pain groups. In the second study, an open-label, two-week pilot study of low back pain, subjects were treated with the patch for two weeks. Results showed that Lidoderm produced significant improvements in pain intensity in all groups and the treatment was well tolerated. Positive results were also reported in trials for the treatment of osteoarthritis knee pain and diabetic neuropathy.

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