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Chronic low back pain (LBP) is a common condition, usually with the involvement of nociceptive and neuropathic pain components, high economic burden and impact on quality of life. Cebranopadol is a potent, first-in-class drug candidate with a novel mechanistic approach, combining nociceptin/orphanin FQ peptide and opioid peptide receptor agonism. We conducted the first phase II, randomized, double-blind, placebo- and active-controlled trial, evaluating the analgesic efficacy, safety, and tolerability of cebranopadol in patients with moderate-to-severe chronic LBP with and without neuropathic pain component. Patients were treated for 14 weeks with cebranopadol 200, 400, or 600 μg once daily, tapentadol 200 mg twice daily, or placebo. The primary efficacy endpoints were the change from baseline pain to the weekly average 24-hour pain during the entire 12 weeks and during week 12 of the maintenance phase. Cebranopadol demonstrated analgesic efficacy, with statistically significant and clinically relevant improvements over placebo for all doses as did tapentadol. The responder analysis (≥30% or ≥50% pain reduction) confirmed these results. Cebranopadol and tapentadol displayed beneficial effects on sleep and functionality. Cebranopadol treatment was safe, with higher doses leading to higher treatment discontinuations because of treatment-emergent adverse events occurring mostly during titration. Those patients reaching the target doses had an acceptable tolerability profile. The incidence rate of most frequently reported treatment-emergent adverse events during maintenance phase was ≤10%. Although further optimizing the titration scheme to the optimal dose for individual patients is essential, cebranopadol is a new drug candidate with a novel mechanistic approach for potential chronic LBP treatment. [ABSTRACT FROM AUTHOR]

Ketamine is often added to opioids in patient-controlled analgesia devices. We tested whether in surgical patients, ketamine added to an opioid patient-controlled analgesia decreased pain intensity by ⩾25%, cumulative opioid consumption by⩾30%, the risk of postoperative nausea and vomiting by⩾30%, the risk of respiratory adverse effects by⩾50%, and increased the risk of hallucination not more than 2-fold. In addition, we searched for evidence of dose-responsiveness. Nineteen randomized trials (1349 adults, 104 children) testing different ketamine regimens added to various opioids were identified through searches in databases and bibliographies (to 04.2016). In 9 trials (595 patients), pain intensity at rest at 24 hours was decreased by 32% with ketamine (weighted mean difference 21.1 cm on the 0-10 cm visual analog scale [98%CI, 21.8 to 20.39], P < 0.001). In 7 trials (495 patients), cumulative 24 hours morphine consumption was decreased by 28% with ketamine (weighted mean difference 212.9 mg [222.4 to 23.35], P = 0.002). In 7 trials (435 patients), the incidence of postoperative nausea and vomiting was decreased by 44% with ketamine (risk ratio 0.56 [0.40 to 0.78], P<0.001). There was no evidence of a difference in the incidence of respiratory adverse events (9 trials, 871 patients; risk ratio 0.31 [0.06 to 1.51], P = 0.08) or hallucination (7 trials, 690 patients; odds ratio 1.16 [0.47 to 2.79], P = 0.70). Trial sequential analyses confirmed the significant benefit of ketamine on pain intensity, cumulative morphine consumption, and postoperative nausea and vomiting and its inability to double the risk of hallucination. The available data did not allow us to make a conclusion on respiratory adverse events or to establish dose-responsiveness. [ABSTRACT FROM AUTHOR]

Neuropathic pain and spasticity after spinal cord injury (SCI) represent significant problems. Palmitoylethanolamide (PEA), a fatty acid amide that is produced in many cells in the body, is thought to potentiate the action of endocannabinoids and to reduce pain and inflammation. This randomized, double-blind, placebo-controlled, parallel multicenter study was performed to investigate the effect of ultramicronized PEA (PEA-um) as add-on therapy on neuropathic pain in individuals with SCI. A pain diary was completed and questionnaires were completed before and after the 12-week treatment with either placebo or PEA-um. The primary outcome measure was the change in mean neuropathic pain intensity from the 1-week baseline period to the last week of treatment measured on a numeric rating scale ranging from 0 to 10. The primary efficacy analysis was the intention to treat (baseline observation carried forward). Secondary outcomes included a per protocol analysis and effects on spasticity, evoked pain, sleep problems, anxiety, depression, and global impression of change. We randomized 73 individuals with neuropathic pain due to SCI, of which 5 had a major protocol violation, and thus 68 were included in the primary analysis. There was no difference in mean pain intensity between PEA-um and placebo treatment (P = 0.46, mean reductions in pain scores 0.4 (-0.1 to 0.9) vs 0.7 (0.2-1.2); difference of means 0.3 (-0.4 to 0.9)). There was also no effect of PEA-um as add-on therapy on spasticity, insomnia, or psychological functioning. PEA was not associated with more adverse effects than placebo. [ABSTRACT FROM AUTHOR]

Over the last decade, the apparent increase in placebo responses in randomized controlled trials (RCTs) of neuropathic pain have complicated and potentially limited development and availability of new effective pain medication. Placebo analgesia and nocebo hyperalgesia effects are well described in nociceptive and idiopathic pain conditions, but less is known about the magnitude and mechanisms of placebo and nocebo effects in neuropathic pain. In neuropathic pain, placebo treatments have primarily been used as control conditions for active agents under investigation in RCTs and these placebo responses are typically not controlled for the natural history of pain and other confounding factors. Recently, mechanistic studies that control for the natural history of pain have investigated placebo and nocebo effects in neuropathic pain in their own right. Large placebo analgesia but no nocebo hyperalgesic effects have been found, and the underlying mechanisms are beginning to be elucidated. Here we review placebo and nocebo effects and the underlying mechanisms in neuropathic pain and compare them with those of nociceptive and idiopathic pain. This allows for a novel discussion on how knowledge of psychological, neurobiological, and genetic factors underlying well-controlled placebo effects may help improve the information that can be obtained from and potentially restore the utility of RCTs. [ABSTRACT FROM AUTHOR]

Internet-delivered interventions are emerging as a strategy to address barriers to care for individuals with chronic pain. This is the first large multicenter randomized controlled trial of Internet-delivered cognitive-behavioral therapy (CBT) for pediatric chronic pain. Participants included were 273 adolescents (205 females and 68 males), aged 11 to 17 years with mixed chronic pain conditions and their parents, who were randomly assigned in a parallel-group design to Internet-delivered CBT (n = 138) or Internet-delivered Education (n = 135). Assessments were completed before treatment, immediately after treatment, and at 6-month follow-up. All data collection and procedures took place online. The primary analysis used linear growth models. Results demonstrated significantly greater reduction on the primary outcome of activity limitations from baseline to 6-month follow-up for Internet CBT compared with Internet education (b = -1.13, P = 0.03). On secondary outcomes, significant beneficial effects of Internet CBT were found on sleep quality (b = 0.14, P = 0.04), on reducing parent miscarried helping (b = -2.66, P = 0.007) and protective behaviors (b = -0.19, P = 0.001), and on treatment satisfaction (P values < 0.05). On exploratory outcomes, benefits of Internet CBT were found for parent-perceived impact (ie, reductions in depression, anxiety, self-blame about their adolescent's pain, and improvement in parent behavioral responses to pain). In conclusion, our Internet-delivered CBT intervention produced a number of beneficial effects on adolescent and parent outcomes, and could ultimately lead to wide dissemination of evidence-based psychological pain treatment for youth and their families. [ABSTRACT FROM AUTHOR]

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. Primary efficacy results showed a statistically significant difference in average pain intensity from randomization baseline to treatment week 12 between the Xtampza ER and placebo groups (mean [±SE], -1.56 [0.267]; P < 0.0001). All sensitivity analyses results supported the primary result of the study. Secondary efficacy outcomes indicated that Xtampza ER vs placebo had more patients with improvement in patient global impression of change (26.4% vs 14.3%; P < 0.0001), longer time-to-exit from the study (58 vs 35 days; P = 0.0102), and a greater proportion of patients with ≥30% (49.2% vs 33.2%; P = 0.0013) and ≥50% (38.3% vs 24.5%; P = 0.0032) improvement in pain intensity. 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. [ABSTRACT FROM AUTHOR]

This double-blind, placebo-controlled, 3-period cross-over, 4-treatment option, incomplete block study (ClinicalTrials.gov number NCT01485185 ), with an adaptive design for sample size re-estimation, was designed to evaluate gabapentin plus donepezil in an established experimental model of electrical hyperalgesia. Thirty healthy male subjects aged 18–55 years were randomized to receive gabapentin 900 mg or gabapentin 900 mg + donepezil 5 mg for 2 of the 3 treatment periods, with 50% of subjects randomized to receive placebo (negative control) and 50% to gabapentin 1800 mg (positive control) for the remaining period. Each treatment period was 14 days. Gabapentin or corresponding placebo was administered on Day 13 and the morning of Day 14. Donepezil or corresponding placebo was administered nocturnally from Day 1–13 and the morning of Day 14. Co-primary endpoints were the area of pinprick hyperalgesia (260 mN von Frey filament) and allodynia (stroking by cotton bud) evoked by electrical hyperalgesia on Day 14. Gabapentin 1800 mg (n = 14) significantly reduced the area of allodynia vs placebo (n = 14; −12.83 cm 2 ; 95% confidence interval [CI] −23.14 to −2.53; P = 0.015) with supportive results for hyperalgesia (−14.04 cm 2 ; 95% CI −28.49–0.41; P = 0.057), validating the electrical hyperalgesia model. Gabapentin + donepezil (n = 30) significantly reduced the area of hyperalgesia vs gabapentin 900 mg (n = 30; −11.73 cm 2 ; 95% CI −21.04 to −2.42; P = 0.014), with supportive results for allodynia (−6.62 cm 2 ; 95% CI −13.29–0.04; P = 0.052). The adverse event profile for gabapentin + donepezil was similar to the same dose of gabapentin. Data are supportive of further clinical investigation of a gabapentin-and-donepezil combination in patients with an inadequate response to gabapentin. [ABSTRACT FROM AUTHOR]