Pain
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Randomized Controlled Trial Multicenter Study
A phase 3, multi-center, randomized, double-blind, placebo-controlled, safety, tolerability, and efficacy study of Xtampza ERTM in patients with moderate-to-severe chronic low back pain.
Opioid analgesics are commonly used for the treatment of chronic low back pain (CLBP); however, abuse potential is a major concern. This study used a randomized, double-blind, placebo-controlled, enriched-enrollment randomized-withdrawal study design to evaluate the safety, tolerability, and analgesic efficacy of an abuse-deterrent formulation of extended-release oxycodone, Xtampza ER, in opioid-naive and opioid-experienced adults with moderate-to-severe CLBP. Patients entered an open-label titration phase (N = 740); those who were successfully titrated on Xtampza ER (≥40 to ≤160 mg oxycodone hydrochloride equivalent per day) were randomized to active drug (N = 193) or placebo (N = 196) for 12 weeks. ⋯ There was less rescue medication (acetaminophen) use in the Xtampza ER treatment group than in the placebo group. Xtampza ER had an adverse event profile consistent with other opioids and was well tolerated; no new safety concerns were identified. In conclusion, Xtampza ER resulted in clinically and statistically significant efficacy in patients with CLBP.
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We have recently shown that subjects can learn to use cognitive-emotional strategies to suppress their spinal nociceptive flexor reflex (RIII reflex) under visual RIII feedback and proposed that this reflects learned activation of descending pain inhibition. Here, we investigated whether learned RIII suppression also affects supraspinal nociception and whether previous relaxation training increases success. Subjects were trained over 3 sessions to reduce their RIII size by self-selected cognitive-emotional strategies. ⋯ The present results show that learned RIII suppression also affects supraspinal nociception as quantified by SEPs, although effects on pain ratings were less clear. Lower motor neuron excitability as quantified by F-waves was not affected. Previous relaxation training did not significantly improve RIII feedback training success.
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Complex regional pain syndrome (CRPS) type I is characterized by somatosensory and motor deficits, and abnormalities have been reported for primary somatosensory (S1) and motor cortex (M1) excitability. For the latter, reduced short-latency intracortical inhibition (SICI) has been demonstrated in the somatotopic representation of the affected side. Recently, an intervention of applying anesthetic cream to the forearm has been shown to modulate both somatosensory deficits (eg, spatial tactile resolution [STR]) and SICI measured in hand muscles. ⋯ Pain intensity was not modulated after intervention. At both hemispheres, SICI was decreased compared with reference values but selectively increased at the intervention side only after analgesic cream and not after placebo. Temporary deafferentation of an area neighbouring the CRPS-affected region can modulate neuropathological characteristics of CRPS and might be a promising strategy for therapeutic interventions.
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The pathophysiology and underlying pain mechanisms of temporomandibular disorders (TMD) are poorly understood. The aims were to assess somatosensory function at the temporomandibular joints (TMJs) and to examine whether conditioned pain modulation (CPM) differs between TMD pain patients (n = 34) and healthy controls (n = 34). Quantitative sensory testing was used to assess the somatosensory function. ⋯ There was a significant CPM effect (increased PPT) at both test sites during painful cold application in healthy controls and patients (P < 0.001). There was no significant difference in the relative CPM effect during painful cold application between groups (P = 0.227). In conclusion, somatosensory abnormalities were commonly detected in TMD pain patients and CPM effects were similar in TMD pain patients and healthy controls.