A randomized, placebo-controlled trial of oxycodone and of gabapentin for acute pain in herpes zoster.

Although acute pain in patients with herpes zoster can be severe and has a substantial impact on health-related quality of life, there have been no randomized clinical trials of oral medications specifically for its ongoing treatment. A randomized clinical trial was conducted in which 87 subjects >or=50 years of age with herpes zoster within 6 calendar days of rash onset and with worst pain in the past 24h >or=3 on a 0-10 rating scale initiated 7 days of treatment with famciclovir in combination with 28 days of treatment with either controlled-release (CR) oxycodone, gabapentin, or placebo. Subjects were evaluated for adverse effects of treatment, acute pain, and health-related quality of life. The results showed that CR-oxycodone and gabapentin were generally safe and were associated with adverse events that reflect well-known effects of these medications. Discontinuing participation in the trial, primarily associated with constipation, occurred more frequently in subjects randomized to CR-oxycodone (27.6%) compared with placebo (6.9%). Treatment with CR-oxycodone reduced the mean worst pain over days 1-8 (p=0.01) and days 1-14 (p=0.02) relative to placebo but not throughout the entire 28-day treatment period as pain resolved in most subjects. Gabapentin did not provide significantly greater pain relief than placebo, although the data for the first week were consistent with a modest benefit. By demonstrating that CR-oxycodone is safe, generally adequately tolerated, and appears to have efficacy for relieving acute pain, the results of this clinical trial provide a foundation for evidence-based treatment for acute pain in herpes zoster.

Skin biopsy and quantitative sensory testing do not predict response to lidocaine patch in painful neuropathies.

Predictors of response to neuropathic pain treatment in patients with painful distal sensory neuropathies are lacking. The 5% lidocaine patch is believed to exert its effects on neuropathic pain via a local stabilizing effect on cutaneous sensory afferents. As such, it provides a model to assess whether the status of epidermal innervation as determined by skin biopsy or quantitative sensory testing (QST) of small- and large-diameter sensory afferents might serve as predictors of response to topical, locally active treatment. In this study we assessed associations between epidermal nerve fiber (ENF) densities, sensory nerve conduction studies (NCS), QST, and response to a 5% lidocaine patch in patients with painful distal sensory neuropathies. We observed no association between distal leg epidermal and subepidermal innervation and response to the lidocaine patch. Several patients with complete loss of distal leg ENF showed a response to the lidocaine patch. Similarly we observed no consistent association between treatment response and QST for vibration, cooling, warm, heat-pain, and cold-pain thresholds, or distal sensory NCS. Thus, distal-leg skin biopsy, QST, and sensory NCS cannot be used to identify patients with painful polyneuropathy likely to respond to a lidocaine patch in clinical practice. Further studies are required to clarify precisely the mechanism and site of action of the lidocaine patch in patients with peripheral neuropathic pain.

An open-label study of the lidocaine patch 5% in painful idiopathic sensory polyneuropathy.

OBJECTIVE: Painful idiopathic distal sensory polyneuropathy is common, but has been largely ignored as a model for the evaluation of neuropathic pain therapies. We have therefore conducted a safety, tolerability, and effectiveness study of the lidocaine patch 5% in painful idiopathic distal sensory polyneuropathy. DESIGN: A prospective open-label, flexible dosing, 3-week study period with a 5-week extension. SETTING: Peripheral Neuropathy clinics and Anesthesiology Clinical Research Center at a tertiary care facility. PATIENTS: Twenty subjects with a diagnosis of idiopathic distal sensory polyneuropathy (with or without associated impaired glucose tolerance), with a baseline mean pain daily rating of > or =4 on a visual analog scale. Intervention. Lidocaine patch 5%, maximum of four patches daily for 18 hours. MAIN OUTCOME MEASURE: Change from baseline week to week 3 mean daily diary pain ratings. Secondary endpoints included assessments of safety and tolerability as well as quality of life measures. RESULTS: Subjects with idiopathic distal sensory polyneuropathy, both with and without impaired glucose tolerance, showed significant improvements in pain and quality of life outcome measures over a 3-week treatment period. These improvements were maintained in a subgroup of patients treated for an additional 5 weeks and permitted a taper of concomitant analgesics in 25% of subjects. The lidocaine patch 5% was well tolerated. CONCLUSIONS: The lidocaine patch 5% appeared well tolerated and potentially effective in the management of painful idiopathic distal sensory polyneuropathy. Idiopathic distal sensory polyneuropathy is an appropriate patient population for the conduct of clinical trials of neuropathic pain therapies.

A randomized, placebo-controlled trial of bupropion sustained release in chronic low back pain.

UNLABELLED: Clinical trials of the efficacy of antidepressant drugs in patients with chronic low back pain have had mixed results, possibly because of the different mechanisms of action of the drugs that have been studied. Because bupropion has a mechanism of action that differs from other antidepressants and has shown efficacy in neuropathic pain, a randomized, placebo-controlled, 2-period crossover trial was conducted to evaluate its efficacy in subjects with chronic low back pain. The primary efficacy variable was mean daily diary pain intensity ratings, and secondary pain intensity and relief outcomes included weekly pain intensity ratings, the McGill Pain Questionnaire (MPQ) Present Pain Intensity scale, pain relief ratings, and satisfaction with pain relief ratings. Adverse events were also assessed throughout the trial. Analyses were performed of an intention-to-treat sample of 44 patients, only 3 of whom met criteria for neuropathic low back pain. Daily and weekly pain intensity ratings, the MPQ Present Pain Intensity scale, and pain relief ratings were not significantly different following treatment with bupropion sustained release (SR) vs. placebo. These results suggest that bupropion SR was not significantly better than placebo in the treatment of patients with non-neuropathic chronic low back pain. PERSPECTIVE: Antidepressant medications that have both noradrenergic and serotonergic effects appear to have greater efficacy in patients with chronic low back pain than those with only serotonergic activity. We studied bupropion because it inhibits the reuptake of both norepinephrine and dopamine, but found no evidence of efficacy in patients with non-neuropathic chronic low back pain.

Effectiveness, tolerability, and impact on quality of life of the 5% lidocaine patch in diabetic polyneuropathy.

BACKGROUND: The treatment of painful diabetic polyneuropathy (DPN) is often inadequate and frequently limited by the systemic adverse effects of medications, necessitating the evaluation of novel treatments. OBJECTIVE: To evaluate the effectiveness, tolerability, and impact on quality of life of the 5% lidocaine patch in painful diabetic polyneuropathy. DESIGN: Open-label, flexible-dosing, 3-week study with a 5-week extension. SETTING: Outpatient clinics and clinical research centers.Patients Volunteer sample of 56 patients with clinically defined painful diabetic polyneuropathy of longer than 3 months' duration. Intervention The 5% lidocaine patch, with a maximum of 4 patches daily for 18 hours. MAIN OUTCOME MEASURES: Change in mean daily pain diary ratings from baseline to week 3. Secondary end points included assessments of safety, tolerability, and quality of life. RESULTS: Patients with painful diabetic polyneuropathy showed significant improvements in pain and quality-of-life outcome measures during a 3-week treatment period. These benefits were maintained in a subgroup of patients treated for an additional 5 weeks, during which taper of concomitant analgesic therapy was permitted. Adverse events were minimal, and systemic accumulation of lidocaine did not occur. CONCLUSIONS: Up to four 5% lidocaine patches for up to 18 h/d are well tolerated in patients with painful diabetic polyneuropathy, significantly improve pain and quality-of-life ratings, and may allow tapering of concomitant analgesic therapy. Given the open-label design of this trial, a randomized controlled trial is necessary to confirm these results.

Pharmacotherapy of painful diabetic neuropathy.

The scope of this review is to describe the epidemiology, physiology, symptomatology, and treatment of diabetic painful neuropathy, which is a common complication of diabetes with significant morbidity. This article focuses on treatment options. Various clinical trials of several classes of medications (eg, antidepressants, anticonvulsants, and topical medications) and alternative treatments (eg, acupuncture, electrostimulation, magnets) are reviewed. Physicians have a large panel of medications that can be used effectively solely or in combination at their disposal. However, a number of these treatments have significant side effects, which are noted, that limit their use. As the understanding of the pathophysiologic mechanisms of diabetic neuropathy improves, new medications are under investigation, which are reviewed in this article. There is great hope that the future may hold treatments that would prevent nerve damage.