Pain
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Randomized Controlled Trial
A randomized, double-blind, placebo-controlled trial of a chemokine receptor 2 (CCR2) antagonist in posttraumatic neuralgia.
We evaluated the analgesic efficacy, safety and tolerability of a novel chemokine receptor 2 (CCR2) antagonist, AZD2423, in posttraumatic neuralgia. This was a double-blind, randomized, parallel-group, multicentre study. One hundred thirty-three patients with posttraumatic neuralgia were equally randomized to 28days' oral administration of 20mg AZD2423, 150mg AZD2423 or placebo. ⋯ The CCR2 antagonist AZD2423 demonstrated no efficacy on NRS average pain scores and most of the secondary pain variables. The NPSI data suggested possible effects on certain sensory components of pain. There were no major safety or tolerability concerns.
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This study investigated the effect on observer responses of the presence/absence of information about medical evidence for pain and psychosocial influences on the patient's pain experience. Additionally, the moderating role of the patient's pain expressions and the mediating role of the observer's belief in deception and evaluation of the patient was examined. Sixty-two participants were presented with videos of 4 patients, each accompanied by a vignette describing the presence or absence of both medical evidence for the pain and psychosocial influences on the patient's pain. ⋯ The results indicate that discounting pain in the absence of medical evidence may involve negative evaluation of the patient. Further, the patient's pain expression is a moderating variable, and psychosocial influences negatively impact the degree to which patients' self-reports are taken into account. The results indicate that contextual information impacts observer responses to pain.
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Calcitonin gene-related peptide (CGRP) is known to play a major role in the pathogenesis of pain syndromes, in particular migraine pain. Here we focus on its implication in a rat pain model of inflammation, induced by injection of complete Freund adjuvant (CFA). The nonpeptide CGRP receptor antagonist BIBN4096BS reduces migraine pain and trigeminal neuronal activity. ⋯ The same amount of reduction occurred after topical administration onto the paw, with resulting systemic plasma concentrations in the low nanomolar range. However, spinal administration of BIBN4096BS did not modify the neuronal activity in the CFA model. Peripheral blockade of CGRP receptors by BIBN4096BS significantly alleviates inflammatory pain.
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Best current estimates of neuropathic pain prevalence come from studies using screening tools detecting pain with probable neuropathic features; the proportion experiencing significant, long-term neuropathic pain, and the proportion not responding to standard treatment are unknown. These "refractory" cases are the most clinically important to detect, being the most severe, requiring specialist treatment. The aim of this study was to estimate the proportion of neuropathic pain in the population that is "refractory," and to quantify associated clinical and demographic features. ⋯ Graded categories of chronic pain with and without neuropathic characteristics were generated, incorporating the refractory criteria. Completed questionnaires were returned by 4451 individuals (response rate 47%); 399 had "chronic pain with neuropathic characteristics" (S-LANSS positive, 8.9% of the study sample); 215 (53.9%) also reported a positive relevant history ("Possible neuropathic pain"); and 98 (4.5% of all Chronic Pain) also reported an "adequate" trial of at least one neuropathic pain drug ("Treated possible neuropathic pain"). The most refractory cases were associated with dramatically poorer physical and mental health, lower pain self-efficacy, higher pain intensity and pain-related disability, and greater health care service use.