Is the Capsaicin 179 mg (8% w/w) Cutaneous Patch an Appropriate Treatment Option for Older Patients with Peripheral Neuropathic Pain?

Introduction

Capsaicin 179 mg (8% weight per weight) cutaneous patch ("capsaicin patch") is a recommended topical treatment for peripheral neuropathic pain (PNP). In older patients, topical treatments may be preferred over systemic treatments, but data specific to the older population are scarce.

Methods

We conducted pooled analyses of multiple clinical trials to evaluate efficacy and safety of capsaicin patch in older patients. The analysis of efficacy included four randomized, double-blind, 12-week studies with similar trial design comparing a single treatment of capsaicin 179 mg cutaneous patch vs low-dose control patch in post-herpetic neuralgia. For the safety evaluation, data were pooled from 18 interventional studies in which capsaicin patch was used in PNP with varying etiologies.

Results

Capsaicin patch had similar analgesic efficacy in elderly (n=582) and non-elderly patients (n=545) in terms of change from baseline to 2-12 weeks in the 11-point numeric pain rating scale (NPRS) score for average pain over the previous 24 hours. In both age groups, decrease in NPRS score was significantly greater with capsaicin patch vs control. Older patients treated with capsaicin patch were significantly more likely than those in the control group to achieve responder status (ie mean decrease in NPRS score from baseline to week 2-12 of at least 30% or ≥2 points): 36.1% vs 27.1% (odds ratio [OR] [95% CI] 1.52 [1.06, 2.18]; P=0.0231) and 33.1% vs 20.9% (OR [95% CI] 1.90 [1.30, 2.78]; P=0.0009) for active treatment vs control group, respectively. Similar proportions of non-elderly patients (n=2,311) and elderly patients (n=537) treated with capsaicin patch experienced treatment-emergent adverse events (TEAEs) (81.6% and 78.1%, respectively) and serious TEAEs (8.2% and 7.2%), with application-site reactions the most common TEAEs in both groups.

Conclusion

The capsaicin patch was equally efficacious and well tolerated in older patients as in younger patients.

Systematic review and co-ordinate based meta-analysis to summarize the utilization of functional brain imaging in conjunction with human models of peripheral and central sensitization

BACKGROUND AND OBJECTIVE

Functional magnetic resonance imaging, in conjunction with models of peripheral and/or central sensitization, has been used to assess analgesic efficacy in healthy humans. This review aims to summarize the use of these techniques to characterize brain mechanisms of hyperalgesia/allodynia and to evaluate the efficacy of analgesics.

DATABASES AND DATA TREATMENT

Searches were performed (PubMed-Medline, Cochrane, Web of Science and Clinicaltrials.gov) to identify and review studies. A co-ordinate based meta-analysis (CBMA) was conducted to quantify neural activity that was reported across multiple independent studies in the hyperalgesic condition compared to control, using GingerALE software.

RESULTS

Of 217 publications, 30 studies met the inclusion criteria. They studied nine different models of hyperalgesia/allodynia assessed in the primary (14) or secondary hyperalgesia zone (16). Twenty-three studies focused on neural correlates of hyperalgesic conditions and showed consistent changes in the somatosensory cortex, prefrontal cortices, insular cortex, anterior cingulate cortex, thalamus and brainstem. The CBMA on 12 studies that reported activation coordinates for a contrast comparing the hyperalgesic state to control produced six activation clusters (significant at false discovery rate of 0.05) with more peaks for secondary (17.7) than primary zones (7.3). Seven studies showed modulation of brain activity by analgesics in five of the clusters but also in four additional regions.

CONCLUSIONS

This meta-analysis revealed substantial but incomplete overlap between brain areas related to neural mechanisms of hyperalgesia and those reflecting the efficacy of analgesic drugs. Studies testing in the secondary zone were more sensitive to evaluate analgesic efficacy on central sensitization at brainstem or thalamocortical levels.

SIGNIFICANCE

Experimental pain models that provide a surrogate for features of pathological pain conditions in healthy humans and functional imaging techniques are both highly valuable research tools. This review shows that when used together, they provide a wealth of information about brain activity during pain states and analgesia. These tools are promising candidates to help bridge the gap between animal and human studies, to improve translatability and provide opportunities for identification of new targets for back-translation to animal studies.

[Ketamine in chronic pain]

Ketamine is now frequently used in the management of chronic pain refractory to conventional treatments. However, its efficacy and adverse effects appear variable in the literature in line with heterogeneous methodologies and modes of administration, leading to controversy regarding the actual interest of ketamine for chronic pain treatment. A need for clinical trials on larger cohorts of well selected patients but also real-life studies to more accurately quantify its efficacy, refine its prescription dosages and better understand its long-term adverse effects is highlighted in the literature. Progress in this direction has been achieved in recent years with improved recommendations for use, taking into account different trajectories of analgesia with ketamine, depending on the etiology of the pain, and the psycho-affective profile of patients. A holistic approach is clearly needed with consideration of pain and depression comorbidities to optimize pain management.

Assessing brain function in stressed healthy individuals following the use of a combination of green tea, Rhodiola, magnesium, and B vitamins: an fMRI study

Introduction

This randomized, controlled, single-blinded trial assessed the effect of magnesium (Mg)-Teadiola (Mg, vitamins B6, B9, B12, Rhodiola, and green tea/L-theanine) versus placebo on the brain response to stressful thermal stimulus in chronically stressed, but otherwise healthy subjects. Impacts on stress-related quality-of-life parameters (depression, anxiety, sleep, and perception of pain) were also explored.

Methods

The study recruited a total of 40 adults (20 per group), suffering from stress for more than 1 month and scaling ≥14 points on the Depression Anxiety Stress Scale (DASS)-42 questionnaire at the time of inclusion. Individuals received oral Mg-Teadiola or placebo for 28 days (D). fMRI analysis was used to visualize the interplay between stress and pain cerebral matrices, using thermal stress model, at baseline (D0) and after D28.

Results

Based on blood-oxygen-level-dependent (BOLD) signal variations during the stress stimulation (before pain perception), a significantly increased activation between D0 and D28 was observed for left and right frontal area (p = 0.001 and p = 0.002, respectively), left and right anterior cingulate cortex (ACC) (p = 0.035 and p = 0.04, respectively), and left and right insula (p = 0.034 and p = 0.0402, respectively) in Mg-Teadiola versus placebo group. During thermal pain stimulation, a significantly diminished activation of the pain matrix was observed between D0 and D28, for left and right prefrontal area (both p = 0.001), left and right insula (p = 0.008 and p = 0.019, respectively), and left and right ventral striatum (both p = 0.001) was observed in Mg-Teadiola versus placebo group. These results reinforce the clinical observations, showing a perceived benefit of Mg-Teadiola on several parameters. After 1 month of treatment, DASS-42 stress score significantly decreased in Mg-Teadiola group [effect size (ES) -0.46 (-0.91; -0.01), p = 0.048]. Similar reductions were observed on D14 (p = 0.011) and D56 (p = 0.008). Sensitivity to cold also improved from D0 to D28 for Mg-Teadiola versus placebo [ES 0.47 (0.02; 0.92) p = 0.042].

Conclusion

Supplementation with Mg-Teadiola reduced stress on D28 in chronically stressed but otherwise healthy individuals and modulated the stress and pain cerebral matrices during stressful thermal stimulus.

Assessment of Initial Depressive State and Pain Relief With Ketamine in Patients With Chronic Refractory Pain

Importance

Repeated ketamine administration is common in treatment-refractory chronic pain, but ketamine analgesic and antidepressant effects are poorly understood in patients with chronic pain with depression symptoms.

Objective

To determine clinical pain trajectories with repeated ketamine administrations, exploring whether ketamine dose and/or pretreatment depressive and/or anxiety symptoms may mediate pain relief.

Design, Setting, and Participants

This nationwide, multicenter, prospective cohort study included patients in France with treatment-refractory chronic pain who received repeated ketamine administration, over 1 year, according to ketamine use in their pain clinic. Data were collected from July 7, 2016, through September 21, 2017. Linear mixed models for repeated data, trajectory analysis, and mediation analysis were performed from November 15 to December 31, 2022.

Interventions

Ketamine administration in cumulative dose (milligrams) over 1 year.

Main Outcomes and Measures

Primary outcome was mean pain intensity (0-10 on the Numerical Pain Rating Scale [NPRS]), assessed every month for 1 year by telephone, after inclusion in the hospital. Depression and anxiety (Hospital Anxiety and Depression Scale [HADS]), quality of life (12-item Short Form Health Survey [SF-12]), cumulative ketamine dose, adverse effects, and concomitant treatments were secondary outcomes.

Results

A total of 329 patients (mean [SD] age, 51.4 [11.0] years; 249 women [75.7%] and 80 men [24.3%]) were enrolled. Repeated ketamine administration was associated with a decrease of NPRS (effect size = -0.52 [95% CI, -0.62 to -0.41]; P < .001) and an increase of SF-12 mental health (39.7 [10.9] to 42.2 [11.1]; P < .001) and physical health (28.5 [7.9] to 29.5 [9.2]; P = .02) dimension scores over 1 year. Adverse effects were in the normal range. There was a significant difference between patients without and with depressive symptoms in pain diminution (regression coefficient, -0.04 [95% CI, -0.06 to -0.01]; omnibus P = .002 for interaction of time × baseline depression [HADS score ≤7 or >7]). The mediation model showed that ketamine dose was not associated with pain diminution (r = 0.01; P = .61) and not correlated with depression (r = -0.06; P = .32), and that depression was associated with pain diminution (regression coefficient, 0.03 [95% CI, 0.01-0.04]; P < .001), whereas ketamine dose was not (regression coefficient, 0.00 [95% CI, -0.01 to 0.01]; P = .67). The proportion of reduction of pain mediated by baseline depression was 64.6%.

Conclusions and Relevance

The findings of this cohort study on chronic refractory pain suggest that depression (and not ketamine dose or anxiety) was the mediator of the association of ketamine with pain diminution. This finding provides radically new insights on how ketamine reduces pain primarily by dampening depression. This reinforces the need for systematic holistic assessment of patients with chronic pain to diagnose severe depressive symptoms where ketamine would be a very valuable therapeutic option.

Circulating Human Metabolites Resulting from TOTUM-070 Absorption (a Plant-Based, Polyphenol-Rich Ingredient) Improve Lipid Metabolism in Human Hepatocytes: Lessons from an Original Ex Vivo Clinical Trial

TOTUM-070 is a patented polyphenol-rich blend of five different plant extracts showing separately a latent effect on lipid metabolism and potential synergistic properties. In this study, we investigated the health benefit of such a formula. Using a preclinical model of high fat diet, TOTUM-070 (3 g/kg of body weight) limited the HFD-induced hyperlipemia with a reduction in triglyceride (-32% after 6 weeks; -20.3% after 12 weeks) and non-HDL cholesterol levels (-21% after 6 weeks; -38.4% after 12 weeks). To further investigate such a benefit and its underlying mechanisms in humans, we designed an ex vivo clinical approach to collect the circulating bioactives resulting from TOTUM-070 ingestion and to determine their biological activities on human hepatocytes. Human serum was obtained from healthy subjects before and after intake of TOTUM-070 (4995 mg). The presence of circulating metabolites was assessed by UPLC-MS/MS. Serum containing metabolites was further incubated with hepatocytes cultured in a lipotoxic environment (palmitate, 250 µM). RNA sequencing analyses show that lipid metabolism was one of the most impacted processes. Using histologic, proteomic, and enzymatic assays, the effects of human TOTUM-070 bioactives on hepatocyte metabolism were characterized by (1) the inhibition of lipid storage, including both (2) triglycerides (-41%, p < 0.001) and (3) cholesterol (-50%, p < 0.001) intracellular content, (4) a reduced de novo cholesterol synthesis (HMG-CoA reductase activity -44%, p < 0.001), and (5) a lowered fatty acid synthase protein level (p < 0.001). Altogether, these data support the beneficial impact of TOTUM-070 on lipid metabolism and provide new biochemical insights in human mechanisms occurring in liver cells.

A tactile pain evaluation scale for visually deficient persons

OBJECTIVE

Pain evaluation scales often rely on the sense of sight. There is so far no pain assessment scale specifically designed for persons with visual impairment.

DESIGN

This study aims to validate a tactile pain evaluation scale, Visiodol©, in blind/visually impaired persons, by correlation with a numeric pain scale (NPS).

SETTING

The study took place in University Hospital Clermont-Fd, France.

METHODS

Pain intensity for a range of thermal stimuli (Pathway Medoc®) was evaluated with Visiodol© and NPS; secondary outcomes including pain thresholds, catastrophizing, emotion and quality of life were compared in blind/visually impaired and sighted persons. Lin's concordance correlation coefficient was estimated; weighted Cohen κ accounted for degrees of disagreement between scales with 95% confidence interval (95%CI).

SUBJECTS

21 healthy sighted and 21 healthy non-sighted volunteers (n = 13 congenital, n = 8 acquired) were included.

RESULTS

Lin's correlation coefficient for repeated data was 0.967 (95%CI, 0.956; 0.978; P < 0.001) for visually impaired participants with a good agreement at each temperature plateau. Weighted Cohen κ of 0.90 (95% CI, 0.84-0.92) and 92.9% percentage of agreement for visually impaired participants was satisfactory. Pain perception, psychological components and quality of life were more impaired in blind/visually impaired persons than in sighted persons.

CONCLUSIONS

This study validates Visiodol©, a tactile scale for blind/visually impaired persons and addresses healthcare inequalities in the context of pain evaluation. It will now be tested on a larger population of patients in order to give the millions of blind/visually impaired persons worldwide, an option for pain intensity evaluation in clinical situations.

Benefits of Circulating Human Metabolites from Fish Cartilage Hydrolysate on Primary Human Dermal Fibroblasts, an Ex Vivo Clinical Investigation for Skin Health Applications

Due to its significant exposure to stressful environmental factors, the skin undergoes a high remodeling rate over time, which alters not only its appearance but also its functionality. This alteration of the skin, namely photoaging, is characterized by dryness and a loss of elasticity that mainly originates from the dysregulation of dermal fibroblast activities. In order to overcome such tissue outcome, cosmetic products have evolved toward nutricosmetics, thus promoting beauty from within. Among bio-actives of interest, bio-peptides deriving from plant or animal sources may exert various biological activities beyond their nutritional value. However, studies remain mostly descriptive and the mode of action at the cellular level in clinic remains a concern. In a recent clinical trial, it was showed that supplementation with a fish cartilage hydrolysate (FCH) improved signs of chronological and photoaging-induced skin changes in healthy women. Here, using an original ex vivo clinical approach adapted to nutricosmetic purpose, we further demonstrated that this fish cartilage hydrolysate was absorbed and that the circulating metabolites produced in humans following FCH intake stimulate human dermal fibroblast growth, promote specific hyaluronan production, up-regulate elastin synthesis and inhibit MMP-1 and 3 expression along with the enhancement of TGF-β release. Altogether, these data provide clues on the mechanisms likely contributing to the beneficial impact of FCH on human skin functionality by supporting hydration, elasticity and limiting the expression of catabolic factors involved in photoaging onset.

Paracetamol Use in Patients With Osteoarthritis and Lower Back Pain: Infodemiology Study and Observational Analysis of Electronic Medical Record Data

Background

Lower back pain (LBP) and osteoarthritis (OA) are common musculoskeletal disorders and account for around 17.0% of years lived with disability worldwide; however, there is a lack of real-world data on these conditions. Paracetamol brands are frequently prescribed in France for musculoskeletal pain and include Doliprane, Dafalgan, and Ixprim (tramadol-paracetamol).

Objective

The objective of this retrospective study was to understand the journey of patients with LBP or OA when treated with paracetamol.

Methods

Three studies were undertaken. Two studies analyzed electronic medical records from general practitioners (GPs) and rheumatologists of patients with OA or LBP, who had received at least one paracetamol prescription between 2013 and 2018 in France. Data were extracted, anonymized, and stratified by gender, age, and provider specialty. The third study, an infodemiology study, analyzed associations between terms used on public medical forums and Twitter in France and the United States for OA only.

Results

In the first 2 studies, among patients with LBP (98,998), most (n=92,068, 93.0%) saw a GP, and Doliprane was a first-line therapy for 87.0% (n=86,128) of patients (71.0% [n=61,151] in combination with nonsteroidal anti-inflammatory drugs [NSAIDs] or opioids). Among patients with OA (99,997), most (n=84,997, 85.0%) saw a GP, and Doliprane was a first-line therapy for 83.0% (n=82,998) of patients (62.0% [n=51,459] in combination). Overall, paracetamol monotherapy prescriptions decreased as episodes increased. In the third study, in line with available literature, the data confirmed that the prevalence of OA increases with age (91.5% [212,875/232,650] above 41 years), OA is more predominant in females (46,530/232,650, 20.0%), and paracetamol use varies between GPs and rheumatologists.

Conclusions

This health surveillance analysis provides a better understanding of the journey for patients with LBP or OA. These data confirmed that although paracetamol remains the most common first-line analgesic for patients with LBP and OA, usage varies among patients and health care specialists, and there are concerns over efficacy.

Uncovering a Genetic Polymorphism Located in Huntingtin Associated Protein 1 in Modulation of Central Pain Sensitization Signaling Pathways

Fibromyalgia syndrome (FMS) is characterized by widespread pain and increased sensitivity to nociceptive stimulus or tenderness. While familial aggregation could suggest a potential hereditary component in FMS development, isolation of genetic determinants has proven difficult due to the multi-factorial nature and complexity of the syndrome. Central sensitization is thought to be one of the key mechanisms leading to FMS in a subset of patients. Enhanced central pain signaling can be measured using the Nociceptive Flexion Reflex (NFR) or RIII threshold. We performed a genome-wide association study (GWAS) using an array to genotype 258,756 human genetic polymorphisms in 225 FMS patients and 77 healthy volunteers and searched for genetic variants associated with a lowered NFR threshold. We have identified a potential association between a single nucleotide polymorphism resulting in a common non-synonymous coding mutation in the Huntingtin associated protein 1 (HAP1) gene (rs4796604, MAF = 0.5) and the NFR threshold (p = 4.78E−06). The Hap1 protein is involved in trafficking and is particularly enriched in neurons. Our results suggest a possible involvement of the neuronal trafficking protein HAP1 in modulating pain signaling pathways and thus participate in the establishment of the NFR threshold.

A Combination of Magnesium, B Vitamins, Rhodiola, and Green Tea (L-theanine) Alleviates Chronic Stress in Healthy Volunteers: A Randomized, Placebo-Controlled Study

Objectives

The effect of a combination of magnesium, vitamin B6, B9, B12, and Teadiola^® (rhodiola and green tea/L-theanine extracts) on stress was evaluated in chronically stressed but otherwise healthy subjects. The effects on stress-related quality-of-life (QoL) parameters, like sleep and perception of pain were also explored.

Methods

This single-blinded study (NCT04391452) included adults with stress for ≥1 month and with ≥14 points on Depression Anxiety Stress Scale (DASS)-42 stress questionnaire. Subjects were randomized (1:1) to receive either the dietary supplement combination (n = 49) or placebo (n = 51), once daily, for 28 days, with a follow-up assessment at day 56. Primary endpoint was the change in DASS-42 stress score from baseline (BL) to day 28 in dietary supplement vs placebo groups. Secondary endpoints included changes from BL in DASS-42 scores at days 14 and 56; sleep quality (Pittsburgh Sleep Quality Index [PSQI]) at days 14, 28, and 56; pain perception (temperature threshold) in response to cold/warm thermal stimulations at day 28.

Results

At BL, DASS-42 score (mean [SD]) was 26.3 (6.7) with dietary supplement and 26.8 (8.0) with placebo. At day 28, the scores decreased to 17.6 (7.3) and 20.1 (9.4), respectively, with a significant between-group difference of 3 points (effect size [ES], −0.29; 95% CI [−0.57, −0.01]; p = 0.04). Similar reductions were observed earlier, at day 14 (ES, −0.40; 95% CI [−0.68, −0.11]; p = 0.006), that remained stable up to day 56 (ES, −0.34; 95% CI [−0.62, −0.06]; p = 0.02). At day 28, a significant reduction in sensitivity to cold pain was reported with dietary supplement vs placebo (p = 0.01) and a trend for lesser sensitivity to hot pain was observed (p = 0.06). No significant effect was observed on overall sleep quality, but a trend towards improvement in daytime dysfunction due to sleepiness (PSQI-7 component score) was noticed with dietary supplement vs placebo at day 28 (p = 0.06) which became significant at day 56 (p < 0.001).

Conclusions

The combination is effective for management of stress in healthy individuals. Its beneficial effects on stress-related QoL aspects, notably pain perception, deserve further investigation.

Funding Sources

This study was sponsored by the University Hospital of Clermont-Ferrand, France and received partial financial support from Sanofi Consumer Healthcare, the manufacturer of Stress Resist^®.

Short-Term Magnesium Therapy Alleviates Moderate Stress in Patients with Fibromyalgia: A Randomized Double-Blind Clinical Trial

Patients suffering from fibromyalgia often report stress and pain, with both often refractory to usual drug treatment. Magnesium supplementation seems to improve fibromyalgia symptoms, but the level of evidence is still poor. This study is a randomized, controlled, double-blind trial in fibromyalgia patients that compared once a day oral magnesium 100 mg (Chronomag®, magnesium chloride technology formula) to placebo, for 1 month. The primary endpoint was the level of stress on the DASS-42 scale, and secondary endpoints were pain, sleep, quality of life, fatigue, catastrophism, social vulnerability, and magnesium blood concentrations. After 1 month of treatment, the DASS-42 score decreased in the magnesium and placebo groups but not significantly (21.8 ± 9.6 vs. 21.6 ± 10.8, respectively, p = 0.930). Magnesium supplementation significantly reduced the mild/moderate stress subgroup (DASS-42 stress score: 22.1 ± 2.8 to 12.3 ± 7.0 in magnesium vs. 21.9 ± 11.9 to 22.9 ± 11.9 in placebo, p = 0.003). Pain severity diminished significantly (p = 0.029) with magnesium while the other parameters were not significantly different between both groups. These findings show, for the first time, that magnesium improves mild/moderate stress and reduces the pain experience in fibromyalgia patients. This suggests that daily magnesium could be a useful treatment to improve the burden of disease of fibromyalgia patients and calls for a larger clinical trial.

Effect of a Combination of Magnesium, B Vitamins, Rhodiola, and Green Tea (L-Theanine) on Chronically Stressed Healthy Individuals-A Randomized, Placebo-Controlled Study

The effect of a combination of magnesium, vitamins B6, B9, B12, rhodiola and green tea/L-theanine (Mg-Teadiola) on stress was evaluated in chronically stressed, otherwise healthy individuals. Effects on stress-related quality-of-life parameters (sleep and perception of pain) were also explored. Adults with stress for ≥1 month, scoring ≥14 points on the Depression Anxiety Stress Scale (DASS)-42 questionnaire, were randomized (1:1) to receive oral Mg-Teadiola (n = 49) or a placebo (n = 51), for 28 days, with a follow-up assessment on Day 56 (NCT04391452). The primary endpoint was the change in the DASS-42 stress score from baseline to Day 28 with Mg-Teadiola versus placebo. The DASS-42 stress scores significantly decreased from baseline to Day 28 with Mg-Teadiola versus placebo (effect size, 0.29; 95% CI [0.01, 0.57]; p = 0.04). Similar reductions were observed on Day 14 (p = 0.006) and Day 56 (p = 0.02). A significant reduction in sensitivity to cold pain (p = 0.01) and a trend for lower sensitivity to warm pain was observed (p = 0.06) on Day 28. Improvements in daytime dysfunction due to sleepiness (Pittsburgh Sleep Quality Index-7 component score) were reported on Day 28, and were significant on Day 56 (p < 0.001). Mg-Teadiola is effective in managing stress in otherwise healthy individuals. Its beneficial effects on sleep and pain perception need further investigation.

Effect of magnesium and vitamin B6 supplementation on mental health and quality of life in stressed healthy adults: Post‐hoc analysis of a randomised controlled trial

Magnesium status and vitamin B6 intake have been linked to mental health and/or quality of life (QoL). In an 8-week Phase IV randomised controlled study in individuals with low magnesemia and severe/extremely severe stress but who were otherwise healthy, greater stress reduction was achieved with magnesium combined with vitamin B6 than with magnesium alone. We present a previously unreported secondary analysis of the effect of magnesium, with and without vitamin B6, on depression, anxiety, and QoL. Adults with Depression Anxiety Stress Scales (DASS-42) stress subscale score >18 were randomised 1:1 to magnesium + vitamin B6 combination (Magne B6^® ; daily dose 300 and 30 mg, respectively) or magnesium alone (Magnespasmyl^® ; daily dose 300 mg). Outcomes included changes from baseline in DASS-42 depression and anxiety scores, and QoL (Short Form-36 Health Survey). DASS-42 anxiety and depression scores significantly improved from baseline to week 8 with both treatments, particularly during the first 4 weeks. Improvement in QoL continued over 8 weeks. Participants' perceived capacity for physical activity in daily life showed greater improvement with magnesium + vitamin B6 than magnesium alone (Week 4). In conclusion, magnesium supplementation, with or without vitamin B6, could provide a meaningful clinical benefit in daily life for individuals with stress and low magnesemia.

Evaluating the role of orange juice, HESPERidin in vascular HEALTH benefits (HESPER-HEALTH study): protocol for a randomised controlled trial

INTRODUCTION

Although epidemiological studies associate the consumption of sugary beverages with adverse health effects, human experimental studies have demonstrated substantially different metabolic responses when 100% fruit juices are compared with artificial beverages. Fruit juices do not just provide sugars and associated calories, but they are also rich in bioactive compounds. Flavanones are bioactives specifically and abundantly found in citrus foods, with hesperidin as the major representative in sweet oranges. Flavanone intake has been associated with a lower incidence of mortality from cardiovascular disease (CVD). However, clinical evidence are too scarce to confirm the vasculoprotective effects of 100% orange juice (OJ) presumably mediated by flavanones and thereby do not allow firm conclusions to be drawn about their efficacy.

METHODS AND ANALYSIS

The HESPER-HEALTH study aims to assess the efficacy of OJ in improving vascular function and the contribution of hesperidin to these effects. This double-blind, randomised, controlled, crossover study will be carried out in 42 volunteers predisposed to CVD, based on age and on overweight. It includes three 6-week periods of consumption of 330 mL/d of OJ versus control drinks with and without hesperidin at a dose in agreement with a daily OJ serving (approx. 200-215 mg). The primary outcome is endothelial function, assessed by flow mediated dilation, with measurements performed at fasting and postprandially in response to a challenge meal. The secondary outcomes include bioavailability and metabolism of flavanones, changes in other markers of vascular function, systemic biomarkers of cardiovascular risk, endothelial dysfunction and inflammation, vitamin C and carotenoids status, anthropometry and body composition, gut microbiota composition, nutrigenomic response and in oxylipin profiling.

ETHICS AND DISSEMINATION

This ongoing study was approved by the Ethics committee Sud-Est III, Bron, France on 17 November 2020. The trial is registered on ClinicalTrials.gov. The results will be disseminated in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04731987; Pre-results.

Topical Lidocaine for Chronic Pain Treatment

Topical lidocaine is widely used in current practice for a variety of pain conditions. This literature review shows that its limited absorption and relative lack of systemic adverse events are an attractive analgesic option for a number of vulnerable patients. Topical lidocaine has been approved by health authorities for the treatment of post-herpetic neuralgia in a number of countries, and studies present some degree of evidence of its efficacy and safety in postsurgical pain, diabetic peripheral neuropathy, carpal tunnel syndrome, chronic lower back pain and osteoarthritis. Topical lidocaine may be a great alternative alone or in addition to systemic drugs and non-pharmacological approaches for an optimized pain management and in multimodal analgesia.

Effects of Totum-63 on glucose homeostasis and postprandial glycemia: a translational study

Global prevalence of type 2 diabetes (T2D) is rising and may affect 700 million people by 2045. Totum-63 is a polyphenol-rich natural composition developed to reduce the risk of T2D. We first investigated the effects of Totum-63 supplementation in high-fat diet (HFD)-fed mice for up to 16 wk and thereafter assessed its safety and efficacy (2.5 g or 5 g per day) in 14 overweight men [mean age 51.5 yr, body mass index (BMI) 27.6 kg·m^-2] for 4 wk. In HFD-fed mice, Totum-63 reduced body weight and fat mass gain, whereas lean mass was unchanged. Moreover, fecal energy excretion was higher in Totum-63-supplemented mice, suggesting a reduction of calorie absorption in the digestive tract. In the gut, metagenomic analyses of fecal microbiota revealed a partial restoration of HFD-induced microbial imbalance, as shown by principal coordinate analysis of microbiota composition. HFD-induced increase in HOMA-IR score was delayed in supplemented mice, and insulin response to an oral glucose tolerance test was significantly reduced, suggesting that Totum-63 may prevent HFD-related impairments in glucose homeostasis. Interestingly, these improvements could be linked to restored insulin signaling in subcutaneous adipose tissue and soleus muscle. In the liver, HFD-induced steatosis was reduced by 40% (as shown by triglyceride content). In the subsequent study in men, Totum-63 (5 g·day^-1) improved glucose and insulin responses to a high-carbohydrate breakfast test (84% kcal carbohydrates). It was well tolerated, with no clinically significant adverse events reported. Collectively, these data suggest that Totum-63 could improve glucose homeostasis in both HFD-fed mice and overweight individuals, presumably through a multitargeted action on different metabolic organs.NEW & NOTEWORTHY Totum-63 is a novel polyphenol-rich natural composition developed to reduce the risk of T2D. Totum-63 showed beneficial effects on glucose homeostasis in HFD-fed mice, presumably through a multitargeted action on different metabolic organs. Totum-63 was well tolerated in humans and improved postprandial glucose and insulin responses to a high-carbohydrate breakfast test.

Real-Life Management Pathways for Chronic Peripheral Neuropathic Pain at Tertiary Pain Clinics in France

OBJECTIVE

Peripheral neuropathic pain (PNP) represents a major public health issue. Severe or refractory cases warrant tertiary multidisciplinary management, but little information is available about real-life care pathways. The primary objective of this cross-sectional, observational study was to investigate the pathways of patients with PNP consulting for the first time or followed for less than 1 year in French tertiary specialized pain clinics.

METHODS

PNP was diagnosed with the NeuPSIG algorithm. Data collected included demographics, pain characteristics, and details of management before and after the study visit (e.g., drug and non-drug treatment, nature of medical visits), as well as time to referral to a pain clinic and time to a diagnosis of PNP. Factors associated with delayed referral or diagnosis were analyzed with multivariate analysis.

RESULTS

A total of 404 patients with PNP (age 55.8 ± 15.6 years, 60.3% females, 78.3% retired or unemployed, pain duration 43.4 ± 68.9 months) were enrolled by 84 pain specialists. Pain affected mainly the lower limbs (53.5%) and was predominantly related to surgery or trauma (59.4%). Primary care management was characterized by a high proportion of conventional analgesics (60.7%). Time to referral to a pain clinic was 43.4 ± 68.9 months since pain onset and 20.1 ± 39.4 months since the diagnosis of PNP. Delayed referral to a pain clinic was independently predicted by the clinical specialty of the referring doctor and by male gender.

CONCLUSIONS

This study highlights the need for accessible guidance for non-pain specialists to improve their diagnostic and management skills and for faster referral of patients with PNP to tertiary pain clinics.

Human surrogate models of central sensitization: A critical review and practical guide

Background

As in other fields of medicine, development of new medications for management of neuropathic pain has been difficult since preclinical rodent models do not necessarily translate to the clinics. Aside from ongoing pain with burning or shock‐like qualities, neuropathic pain is often characterized by pain hypersensitivity (hyperalgesia and allodynia), most often towards mechanical stimuli, reflecting sensitization of neural transmission.

Data treatment

We therefore performed a systematic literature review (PubMed‐Medline, Cochrane, WoS, ClinicalTrials) and semi‐quantitative meta‐analysis of human pain models that aim to induce central sensitization, and generate hyperalgesia surrounding a real or simulated injury.

Results

From an initial set of 1569 reports, we identified and analysed 269 studies using more than a dozen human models of sensitization. Five of these models (intradermal or topical capsaicin, low‐ or high‐frequency electrical stimulation, thermode‐induced heat‐injury) were found to reliably induce secondary hyperalgesia to pinprick and have been implemented in multiple laboratories. The ability of these models to induce dynamic mechanical allodynia was however substantially lower. The proportion of subjects who developed hypersensitivity was rarely provided, giving rise to significant reporting bias. In four of these models pharmacological profiles allowed to verify similarity to some clinical conditions, and therefore may inform basic research for new drug development.

Conclusions

While there is no single “optimal” model of central sensitization, the range of validated and easy‐to‐use procedures in humans should be able to inform preclinical researchers on helpful potential biomarkers, thereby narrowing the translation gap between basic and clinical data.

Significance

Being able to mimic aspects of pathological pain directly in humans has a huge potential to understand pathophysiology and provide animal research with translatable biomarkers for drug development. One group of human surrogate models has proven to have excellent predictive validity: they respond to clinically active medications and do not respond to clinically inactive medications, including some that worked in animals but failed in the clinics. They should therefore inform basic research for new drug development.

137 Giant Lipomas of The Hand; A Case Series and Review of a Rare Tumour

Introduction

Whilst lipomas are the most common tumour of the human body, it is rare in the hand. Less than 50-cases are reported in the literature. We present six-cases from a specialist hand unit, UK, presenting over a 10-year period. All patients had a distinct swelling within the affected hand which was growing in size.

Method

Patients were investigated with MRI and given the benign appearance; no pre-excision biopsies were performed. All excised tissue was sent for histology. Only one patient reported altered neurology of the hand, describing altered sensation within the ulnar nerve distribution of the index finger.

Results

In all cases, the lipoma originated in the deep palmar space from adipose tissue surrounding the deep palmar arch. They all extended distally, along natural tissue planes, encasing neurovascular and tendinous structures. In two cases the lipoma extended into the dorsum of the hand, following the perforating artery between the index and middle metacarpal heads. The lipomas all spread radialwards, penetrating the thenar muscles. The largest was 13x12x4cm in size.

Conclusions

Giant lipoma is a rare cause of symptomatic swelling of the hand. Compression of structures is extremely rare, but careful excision is critical as neurovascular bodies are classically enveloped within the growing lipoma.

Challenges and opportunities in translational pain research - An opinion paper of the working group on translational pain research of the European pain federation (EFIC)

For decades, basic research on the underlying mechanisms of nociception has held promise to translate into efficacious treatments for patients with pain. Despite great improvement in the understanding of pain physiology and pathophysiology, translation to novel, effective treatments for acute and chronic pain has however been limited, and they remain an unmet medical need. In this opinion paper bringing together pain researchers from very different disciplines, the opportunities and challenges of translational pain research are discussed. The many factors that may prevent the successful translation of bench observations into useful and effective clinical applications are reviewed, including interspecies differences, limited validity of currently available preclinical disease models of pain, and limitations of currently used methods to assess nociception and pain in non-human and human models of pain. Many paths are explored to address these issues, including the backward translation of observations made in patients and human volunteers into new disease models that are more clinically relevant, improved generalization by taking into account age and sex differences, and the integration of psychobiology into translational pain research. Finally, it is argued that preclinical and clinical stages of developing new treatments for pain can be improved by better preclinical models of pathological pain conditions alongside revised methods to assess treatment-induced effects on nociception in human and non-human animals. Significance: For decades, basic research of the underlying mechanisms of nociception has held promise to translate into efficacious treatments for patients with pain. Despite great improvement in the understanding of pain physiology and pathophysiology, translation to novel, effective treatments for acute and chronic pain has however been limited, and they remain an unmet medical need.

Non-specific analgesia during a clinical trial in fibromyalgia

BACKGROUND

When patients suffering from fibromyalgia undergo a therapeutic trial, a non-negligible part of analgesia is not explained by the drug itself. The mechanisms of this non-specific effect need to be understood.

MATERIALS AND METHODS

We undertook secondary analyses of a double-blind randomized trial in fibromyalgia patients in which 100 mg/day milnacipran was not found superior to placebo. Data from 49 patients belonging to both groups were pooled. Both before treatment and one month after treatment, all patients underwent a CaNTAB^® neuropsychological test (related to spatial planning, reaction time, decision-making and risk-taking, and ability to name objects), and measurements of sensation and pain thresholds to heat and cold, supraliminal heat pain threshold, punctuate mechanical pain threshold and temporal summation, mechanical allodynia to skin brushing, and response to conditioned pain modulation. We studied the baseline predictors of analgesia and the indicators of change associated to analgesia separately. A stepwise approach was used to select the factors to enter into the final ANCOVAs, in which age, body mass index, treatment group and pain at baseline were covariates.

RESULTS

No baseline predictor of non-specific analgesia other than pain at baseline was found to be predictive. Conversely, several neuropsychological (higher performance) or psychophysical (lower sensitivity) changes correlated with analgesia in unadjusted analyses. Multivariable analyses identified increases in warm/heat thermal thresholds and an increased ability to name objects, as factors associated with analgesia.

CONCLUSIONS

The changes observed concomitantly to non-specific pain analgesia might be related to mild changes in brain functioning, based on convergent literature data.

Traitements pharmacologiques et non pharmacologiques de la douleur neuropathique : une synthèse des recommandations françaises

Les douleurs neuropathiques (DN) restent très difficiles à soulager. Plusieurs recommandations ont été proposées au cours de ces dernières années, mais aucune n’a pris en compte à ce jour l’ensemble des approches thérapeutiques disponibles. Nous avons réalisé une revue systématique portant sur toutes les études concernant le traitement des DN périphériques et centrales de l’adulte et de l’enfant, publiées jusqu’en janvier 2018 et avons évalué la qualité des études et le niveau de preuve des traitements au moyen du système GRADE. Les principaux critères d’inclusion étaient l’existence d’une DN chronique (≥ 3 mois), une méthodologie contrôlée et randomisée, un suivi supérieur ou égal à trois semaines, un nombre de patients supérieur ou égal à dix par groupe et une évaluation en double insu pour les traitements pharmacologiques. Sur la base du GRADE, nous recommandons en première intention les antidépresseurs inhibiteurs mixtes de recapture des monoamines (duloxétine et venlafaxine), les antidépresseurs tricycliques, la gabapentine pour toute DN, et les emplâtres de lidocaïne 5 % et la stimulation électrique transcutanée pour les DN périphériques localisées. Nous recommandons en deuxième intention la prégabaline, le tramadol (avec les précautions d’emploi afférentes aux opioïdes) et certaines associations pharmacologiques (antidépresseurs et gabapentine ou prégabaline) pour toute DN, et les patchs de haute concentration de capsaïcine (8 %) et la toxine botulique de type A (en milieu spécialisé) pour les DN périphériques localisées. Nous recommandons en troisième intention la stimulation magnétique transcrânienne répétitive à haute fréquence du cortex moteur (en milieu spécialisé) et les opioïdes forts (en l’absence d’alternative et en respectant les précautions d’emploi afférentes aux opioïdes) pour toute douleur neuropathique, et la stimulation médullaire pour les douleurs radiculaires chroniques postchirurgicales et la polyneuropathie diabétique douloureuse. La psychothérapie (thérapie cognitivocomportementale et thérapie de pleine conscience) peut être recommandée en deuxième intention en association avec les traitements précédents.

Topical Treatment of Localized Neuropathic Pain in the Elderly

The prevalence of neuropathic pain in the older population has been reported to be very high and is most commonly localized to a circumscribed area. Treatment failure is frequent in neuropathic pain and is accompanied by central side effects with recommended oral drugs acting on the central nervous system. A number of topical pharmaceuticals are available on prescription and also sold over the counter. This review in persons aged older than 60 years shows the efficacy of lidocaine 5% and capsaicin 8% for localized neuropathic pain while results with other pharmaceuticals are rather inconsistent. Local application of drugs has a very limited systemic effect and the pharmacological advantages of local over systemic treatment are particularly interesting in older persons who often have comorbidities and take multiple medications. However, more information is needed on the efficacy and safety of lidocaine 5% and capsaicin 8% in older old persons and on the long-term effects of these pharmaceuticals. These studies should also pave the way for research and development in the field of topical analgesics with a satisfactory level of evidence-based medicine.

Pharmacological and non-pharmacological treatments for neuropathic pain: Systematic review and French recommendations

Neuropathic pain remains a significant unmet medical need. Several recommendations have recently been proposed concerning pharmacotherapy, neurostimulation techniques and interventional management, but no comprehensive guideline encompassing all these treatments has yet been issued. We performed a systematic review of pharmacotherapy, neurostimulation, surgery, psychotherapies and other types of therapy for peripheral or central neuropathic pain, based on studies published in peer-reviewed journals before January 2018. The main inclusion criteria were chronic neuropathic pain for at least three months, a randomized controlled methodology, at least three weeks of follow-up, at least 10 patients per group, and a double-blind design for drug therapy. Based on the GRADE system, we provide weak-to-strong recommendations for use and proposal as a first-line treatment for SNRIs (duloxetine and venlafaxine), gabapentin and tricyclic antidepressants and, for topical lidocaine and transcutaneous electrical nerve stimulation specifically for peripheral neuropathic pain; a weak recommendation for use and proposal as a second-line treatment for pregabalin, tramadol, combination therapy (antidepressant combined with gabapentinoids), and for high-concentration capsaicin patches and botulinum toxin A specifically for peripheral neuropathic pain; a weak recommendation for use and proposal as a third-line treatment for high-frequency rTMS of the motor cortex, spinal cord stimulation (failed back surgery syndrome and painful diabetic polyneuropathy) and strong opioids (in the absence of an alternative). Psychotherapy (cognitive behavioral therapy and mindfulness) is recommended as a second-line therapy, as an add-on to other therapies. An algorithm encompassing all the recommended treatments is proposed.

Ketamine and depression: a narrative review

Depression is the third leading cause of disability in the world. Depressive symptoms may be reduced within several weeks after the start of conventional antidepressants, but treatment resistance concerns one-third of patients who fail to achieve recovery. Over the last 20 years, ketamine, an antagonist of the N-methyl-D-aspartate receptor, has been described to have antidepressant properties. A literature review was conducted through an exhaustive electronic search. It was restricted to Cochrane reviews, meta-analyses, and randomized controlled trials (RCTs) of ketamine for major depressive disorder and/or bipolar disorder. This review included two Cochrane reviews, 14 meta-analyses and 15 trials. Ketamine was studied versus placebo, versus other comparators and as an anesthetic adjuvant before electroconvulsive therapy. In 14 publications, ketamine provided a rapid antidepressant effect with a maximum efficacy reached at 24 hrs. Its effect lasted for 1–2 weeks after infusion, but a longer-term effect is little reported. Ketamine does not seem to improve depressive symptoms at the end of electroconvulsive sessions. Safety and tolerability profiles with ketamine at low single dose are generally good in depressed patients. However, there is a lack of data concerning ketamine with repeated administration at higher doses. The clinical use of ketamine is increasing. Intranasal (S)-ketamine has recently been approved for depression by the Food and Drug Administration. It could be a promising treatment in depressed patients with suicidal ideation. Collectively, the level of proof of efficacy remains low and more RCTs are needed to explore efficacy and safety issues of ketamine in depression.

Dextromethorphan and memantine after ketamine analgesia: a randomized control trial

Purpose

Intravenous ketamine is often prescribed in severe neuropathic pain. Oral N-methyl-D-aspartate receptor (NMDAR) antagonists might prolong pain relief, reducing the frequency of ketamine infusions and hospital admissions. This clinical trial aimed at assessing whether oral dextromethorphan or memantine might prolong pain relief after intravenous ketamine.

Patients and methods

A multicenter randomized controlled clinical trial included 60 patients after ketamine infusion for refractory neuropathic pain. Dextromethorphan (90 mg/day), memantine (20 mg/day) or placebo was given for 12 weeks (n=20 each) after ketamine infusion. The primary endpoint was pain intensity at one month. Secondary endpoints included pain, sleep, anxiety, depression, cognitive function and quality of life evaluations up to 12 weeks.

Results

At 1 month, dextromethorphan maintained ketamine pain relief (Numeric Pain Scale: 4.01±1.87 to 4.05±2.61, p=0.53) and diminished pain paroxysms (p=0.03) while pain intensity increased significantly with memantine and placebo (p=0.04). At 3 months, pain remained lower than at inclusion (p=0.001) and was not significantly different in the three groups. Significant benefits were observed on cognitive-affective domains and quality of life for dextromethorphan and memantine (p<0.05).

Conclusions

Oral dextromethorphan given after ketamine infusion extends pain relief during one month and could help patients to better cope with pain. Future studies should include larger populations stratified on pharmacogenetics screening. Optimization of an oral drug that could extend ketamine antihyperalgesia, with fewer hospital admissions, remains a prime challenge in refractory neuropathic pain.

Dextromethorphan Analgesia in a Human Experimental Model of Hyperalgesia

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Central pain sensitization is often refractory to drug treatment. Dextromethorphan, an N-methyl-d-aspartate receptor antagonist, is antihyperalgesic in preclinical pain models. The hypothesis is that dextromethorphan is also antihyperalgesic in humans.

Methods

This randomized, double-blind, placebo-controlled, crossover study explores the antihyperalgesic effect of single and repeated 30-mg dose of oral dextromethorphan in 20 volunteers, using the freeze-injury pain model. This model leads to development of primary and secondary hyperalgesia, which develops away from the site of injury and is associated with central sensitization and activation of N-methyl-d-aspartate receptor in the spinal cord. The primary outcome was antihyperalgesia calculated with the area under the curve of the percentage change in mechanical pain threshold (electronic von Frey) on the area of secondary hyperalgesia. The secondary outcomes were mechanical pain threshold on the area of primary hyperalgesia and cognitive (reaction time) effect.

Results

Single 30-mg results are reported. Antihyperalgesia (% · min) is significantly higher on the area of secondary hyperalgesia with dextromethorphan than placebo (median [interquartile range]: 3,029 [746; 6,195] vs. 710 [–3,248; 4,439], P = 0.009, Hedge’s g = 0.8, 95% CI [0.1; 1.4]). On primary hyperalgesia area, mechanical pain threshold 2 h after drug intake is significantly higher with dextromethorphan (P = 0.011, Hedge’s g = 0.63, 95% CI [0.01; 1.25]). No difference in antinociception is observed after thermal painful stimuli on healthy skin between groups. Reaction time (ms) is shorter with placebo than with dextromethorphan (median [interquartile range]: 21.6 [–37.4; 0.1] vs. –1.2 [–24.3; 15.4], P = 0.015, Hedge’s g = 0.75, 95% CI [0.12; 1.39]). Nonserious adverse events occurrence (15%, 3 of 20 volunteers) was similar in both groups.

Conclusions

This study shows that low-dose (30-mg) dextromethorphan is antihyperalgesic in humans on the areas of primary and secondary hyperalgesia and reverses peripheral and central neuronal sensitization. Because dextromethorphan had no intrinsic antinociceptive effect in acute pain on healthy skin, N-methyl-d-aspartate receptor may need to be sensitized by pain for dextromethorphan to be effective.

[Drug management of cancer-related peripheral neuropathic pain: A systematic review of the literature]

The objective of the present systematic literature review was to provide an update on medical treatment of neuropathic pain in cancer patients. The number of cancer patients is steadily increasing. Pain is frequent in cancer patients. Few studies have focused on medical treatment of pain, and especially of neuropathic pain, in current or former cancer patients. The present systematic review of all studies published between December 2012 and August 2018 was intended to estimate the scale of this lack. In all, 27 articles were identified on a systematic PubMed search and from the authors' personal knowledge, confirming that scant data have been published. The heterogeneity of cancer patients, of cancer, and of pain go some way toward explaining this scarcity. Guidelines, founded mainly on results from non-cancer patients, recommend tricyclic antidepressants and antiepileptic drugs; local treatments have the advantage of good systemic tolerance. Larger-scale studies taking account of the etiology of neuropathic pain, its characteristics (strictly neuropathic or mixed) and patient characteristics (awaiting treatment, under treatment, recent or non-recent survivor, or in terminal phase) along the care pathway are needed to improve knowledge. The results of the present literature analysis can help future research.

Hormonal Status and Cognitivo-Emotional Profile in Real-Life Patients With Neuropathic Pain: A Case Control Study

BACKGROUND

The specific impact of neuropathic pain and recommended neuropathic pain treatments on the hormonal and immune status of patients has been so far poorly explored. This study aimed at studying, in real life, the hypothalamic-pituitary-adrenal axis and the cytokine profile of patients with neuropathic pain. It also explored their links with cognition, emotion, quality of life, and drug treatment.

METHODS

This prospective study (clinicaltrials.gov NCT01543425) included 60 patients with neuropathic pain and 60 age- and gender-matched healthy volunteers after obtaining signatures of informed consent. A number of parameters were measured: adrenocorticotropic hormone, cortisol, cortisol awakening response, dehydroepiandrosterone sulphate, sex hormone binding globulin, testosterone, 17-β-estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, cytokines, brain-derived neurotrophic factor, and vitamin D. Psychological parameters were assessed by questionnaires.

RESULTS

Patients with neuropathic pain had lower levels of adrenocorticotropic hormone (P = 0.009) and dehydroepiandrosterone sulphate (P < 0.001) than controls, and the cortisol awakening response was impaired. Patients were more depressed and anxious (P < 0.001) and had a diminished quality of life (P < 0.001), which was influenced by cytokines (P = 0.0067) and testosterone (P = 0.028). Antidepressants and antiepileptics appeared to interfere with testosterone and cognitivo-emotional domains.

CONCLUSION

An impairment of the hormonal status and of the immune system was observed in patients. It identified testosterone as a potential pivotal mediator between antidepressants/antiepileptics and quality of life. Further studies must address the exact impact of different types of drugs on central effects, of gender differences, and of the immune system of neuropathic pain.

Paracetamol and Pain Modulation by TRPV1, UGT2B15, SULT1A1 Genotypes: A Randomized Clinical Trial in Healthy Volunteers

Background

The influence of the genetic polymorphism of enzymes and receptors involved in paracetamol metabolism and mechanism of action has not been investigated. This trial in healthy volunteers investigated the link between paracetamol pain relief and the genetic polymorphism of 23 enzymes and receptors.

Design

This randomized double-blind crossover controlled pilot study took place in the Clinical Pharmacology Department, University Hospital, Clermont-Ferrand, France. Forty-seven Caucasian volunteers were recruited. The trial consisted of two randomized sessions one week apart with oral paracetamol or placebo, and pain changes were evaluated with mechanical pain stimuli. The genetic polymorphism of 23 enzymes and receptors was studied, and correlations were made with pain relief. All tests are two-sided with a type I error at 0.05.

Results

Paracetamol was antinociceptive compared with placebo (222 ± 482 kPaxmin vs 23 ± 431 kPaxmin; P = 0.0047), and the study showed 30 paracetamol responders and 17 paracetamol nonresponders. Responders were characterized by TRPV1rs224534 A allele, UGT2B15rs1902023 TT genotype, and SULT1A1rs9282861 GG genotype (P &lt; 0.05 for all). These findings confirm for the first time the involvement of a specific TRPV1 rs224534 variant in paracetamol antinociception. They also reveal a new antinociceptive role for specific variants of hepatic phase II enzymes associated with paracetamol metabolism.

Conclusions

The study warrants larger clinical trials on these potential genomic markers of paracetamol analgesia in patients. Confirmation of the present findings would open the way to effective individualized pain treatment with paracetamol, the most commonly used analgesic worldwide.

Magnesium for the Management of Chronic Noncancer Pain in Adults: Protocol for a Systematic Review

Background

Chronic pain is a highly prevalent and complex health problem that is associated with a severe symptom burden, as well as substantial economic and social impact. Many patients with chronic pain still suffer from unrelieved or undertreated pain due to the incomplete efficacy and dose-limiting adverse effects of current therapies. Long-term and high-dose opioid use has considerably increased in the past 20 years despite limited evidence supporting its effectiveness in several chronic pain conditions, and serious concerns have emerged regarding adverse effects and potential misuse. Until recently, the steady increase in opioid prescribing rates has been associated with rising opioid-related mortality and other serious problems, emphasizing the need for better nonopioid therapies. Emerging evidence supports the safe use of magnesium in controlling chronic pain, but its overall efficacy and safety is still unclear.

Objective

This paper aims to assess the efficacy and safety of magnesium compared with a placebo for the treatment of chronic noncancer pain.

Methods

We will conduct a detailed search on Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE from their inception until the date the searches are run to identify relevant randomized controlled trials. The reference lists of retrieved studies as well as Web-based trial registries will also be searched. We will include randomized double-blind trials comparing magnesium (at any dose, frequency, or route of administration) with placebo using participant-reported pain assessment. Two reviewers will independently evaluate studies for eligibility, extract data, and assess trial quality and potential bias. Risk of bias will be assessed using criteria outlined in the Cochrane Handbook for Systematic Review of Interventions. Primary outcomes for this review will include any validated measure of pain intensity or pain relief. Dichotomous data will be used to calculate the risk ratio and number needed to treat or harm. The quality of evidence will be assessed using the Grading of Recommendations Assessment, Development and Evaluation approach.

Results

This protocol is grant-funded and has undergone a peer-review process through the Queen’s University Department of Anesthesiology and Perioperative Medicine Vandewater Endowed Studentship. This project is also supported, in part, by the Chronic Pain Network of the Canadian Institutes of Health Research Strategy for Patient-Oriented Research. The electronic database search strategies are currently being developed and modified. The entire review is expected to be completed by January 1, 2019.

Conclusions

The completion of this review is expected to identify available high-quality evidence describing the efficacy and safety of magnesium for the treatment of chronic noncancer pain.

International Registered Report Identifier (IRRID)

PRR1-10.2196/11654

N-acetylcysteine prevents glutathione decrease and does not interfere with paracetamol antinociceptive effect at therapeutic dosage: a randomized double-blind controlled trial in healthy subjects

Paracetamol (APAP) may lead to hepatic changes even at therapeutic dosages. Glutathione (GSH) plays a pivotal role in APAP metabolism as it allows the detoxification of a toxic metabolite. N-Acetylcysteine (NAC) is APAP antidote, is also largely used as a mucoactive drug and is often associated with APAP. This study aims at evaluating if 1- NAC modifies APAP pain efficacy and 2- NAC prevents glutathione depletion with APAP at therapeutic doses. This double-blind randomized controlled study (NCT02206178) was carried out in 24 healthy volunteers. APAP was given for 4 days (1 g ×4 daily) with NAC or with placebo. Thermal pain tests, whole blood GSH, and hepatic enzymes (ASAT, ALAT) were measured before (D0) and after (D4) oral APAP-NAC or APAP-placebo intake. anova for repeated measures adapted to cross-overdesign was performed and a two-tailed type I error was fixed at 5%. The primary endpoint was the area under the curve (0-240 min) of pain intensity (Numerical Scale) after thermal pain stimulation using Pathway-Medoc^® . APAP antinociceptive effect was similar in both groups. GSH was maintained to its baseline value in the APAP/NAC group but diminished in the APAP/placebo group (P = 0.033). This study shows for the first time that APAP antinociceptive effectiveness is not influenced by NAC. It also shows that the effect of APAP at therapeutic dosage on GSH may be counteracted by NAC. These issues are particularly important for patients as APAP is often prescribed for years as a first-line pain treatment and further trials in patients are now warranted.

An Advanced Formulation of a Magnesium Dietary Supplement Adapted for a Long-Term Use Supplementation Improves Magnesium Bioavailability: In Vitro and Clinical Comparative Studies

While general recommendations are for 300-mg magnesium intake a day, an advanced low-dose formulation of magnesium chloride, ChronoMag®, was designed to provide 100 mg of magnesium element, thus decreasing the risk of gastrointestinal side effects and allowing long-term supplementation in health conditions related to low magnesium levels. The present study aimed to compare magnesium release profile and bioavailability between this patented low-dose continuous-release magnesium chloride tablet (100 mg magnesium element) and a reference tablet at the usually prescribed dose (300 mg magnesium element). Magnesium release profile was determined by dissolving the tablets in solutions simulating the gastrointestinal tract environment. A randomized double-blind crossover controlled trial of ChronoMag® versus reference tablet (3 × 100 mg magnesium element tablets) in 12 normo-magnesemic healthy volunteers was conducted to evaluate the bioavailability of the patented magnesium chloride tablets (two 50 mg magnesium tablets, once-a-day intake). While the reference tablet released 100% of its magnesium within 1 h of dissolution, release from the magnesium chloride formulation was continuous for 6 h. Cumulative urinary magnesium levels compared to those with the reference tablet were 76% (0-5 h), 89% (0-10 h), and 87% (0-24 h). Elimination after 24 h was fairly similar with both supplements. Our results suggest that the new magnesium chloride formulation, providing continuous low-dose magnesium release throughout the gastrointestinal tract, improves absorption and bioavailability. This formulation conforms to the physiological mechanism of magnesium absorption throughout the digestive tract, allowing high absorption, and may improve gastrointestinal tolerance in long-term use.

Preventive effect of oral magnesium in postmastectomy pain: protocol for a randomised, double-blind, controlled clinical trial

INTRODUCTION

Breast cancer affects 1 in 10 women worldwide, and mastectomy is a cause of chronic pain with neuropathic characteristics. N-methyl-D-aspartate receptor (NMDAR) antagonists such as ketamine, memantine, dextromethorphan or magnesium are used to treat refractory pain by blocking NMDAR. Oral memantine has been shown to prevent postmastectomy pain and cognitive impact and to maintain quality of life. Likewise, the present study is intended to assess the preventive effect of oral magnesium, administered ahead of mastectomy, on the development of neuropathic pain. As a physiological blocker of NMDAR, magnesium could be an interesting candidate to prevent postoperative pain and associated comorbidities, including cognitive and emotional disorders, multiple analgesic consumption and impaired quality of life.

METHODS AND ANALYSIS

A randomised double-blind controlled clinical trial (NCT03063931) will include 100 women with breast cancer undergoing mastectomy at the Oncology Hospital, Clermont-Ferrand, France. Magnesium (100 mg/day; n=50) or placebo (n=50) will be administered for 6 weeks, starting 2 weeks before surgery. Intensity of pain, cognitive and emotional function and quality of life will be assessed by questionnaires. The primary endpoint is pain intensity on a 0-10 numerical rating scale at 1 month postmastectomy. Data analysis will use mixed models; all tests will be two-tailed, with type-I error set at α=0.05.

ETHICS AND DISSEMINATION

The study protocol and informed consent form were approved in December 2016 by the French Research Ethics Committee (South East VI Committee). Results will be communicated in various congresses and published in international publications.

TRIAL REGISTRATION NUMBER

NCT03063931.

Milnacipran poorly modulates pain in patients suffering from fibromyalgia: a randomized double-blind controlled study

Introduction

Fibromyalgia is characterized by widespread and chronic pain, and its prevalence is increasing worldwide. Milnacipran, an antidepressant, is often prescribed for fibromyalgia with a possible beneficial effect on central pain modulation. The aim of this study was to evaluate if milnacipran could modify the status of conditioned pain modulation (CPM) in patients suffering from fibromyalgia.

Design and setting

Randomized, double-blind controlled trial.

Subjects and methods

Women with fibromyalgia received milnacipran 100 mg or placebo. The primary end point was the evolution of CPM with treatments after a 30-second painful stimulus. Secondary outcomes included the predictability of milnacipran efficacy from CPM performance, evolution of global pain, mechanical sensitivity, thermal pain threshold, mechanical allodynia, cognitive function, and tolerance.

Results

Fifty-four women with fibromyalgia (46.7±10.6 years) were included and randomized, and 24 patients were analyzed in each group. At inclusion, CPM was dysfunctional (CPM₃₀=-0.5±1.9), and global pain was 6.5±1.8. After treatment, there was a nonsignificant CPM difference between milnacipran and placebo (CPM₃₀=-0.46±1.22 vs -0.69±1.43, respectively, p=0.55) and 18.8% vs 6.3% (p=0.085) patients did reactivate CPM after milnacipran vs placebo. Initial CPM was not a predictor of milnacipran efficacy. Global pain, mechanical and thermal thresholds, allodynia, cognition, and tolerance were not significantly different between both groups.

Conclusion

Milnacipran did not display a significant analgesic effect after 1-month treatment, but the tendency of milnacipran to reactivate CPM in a number of patients must be explored with longer treatment duration in future studies and pleads for possible subtypes of fibromyalgia patients.

Effect of ketamine combined with magnesium sulfate in neuropathic pain patients (KETAPAIN): study protocol for a randomized controlled trial

Background

Neuropathic pain is difficult to treat, and the efficacy of recommended drugs remains limited. N-methyl-d-aspartate receptors are implicated, and antagonists are a pharmacological option. Ketamine is widely used in French pain clinics, but without consensus or recommendations. Furthermore, the association of ketamine with magnesium has been poorly studied. The aim of the present study is to evaluate the benefit of ketamine with or without magnesium in refractory neuropathic pain.

Methods/design

A randomized, double-blind, crossover, placebo-controlled study will be performed in Clermont-Ferrand University Hospital, Clermont-Ferrand, France. The aim is to evaluate the effect of ketamine with or without magnesium in 22 patients with neuropathic pain. Intravenous ketamine/placebo, ketamine/magnesium sulfate, or placebo/placebo will be administered consecutively to each patient, in random order, once at 5-week intervals. The primary endpoint is the AUC of pain intensity assessed on a 0–10 Numeric Pain Rating Scale for a 5-week period. Data analysis will be performed on an intention-to-treat basis, and all statistical tests (except primary analysis) will be performed with an α risk of 5% (two-sided).

Discussion

Considering the poor efficacy of the drugs available for neuropathic pain, ketamine with or without magnesium sulfate may be a valuable therapeutic option that needs to be standardized.

Trial registration

EudraCT number–2015-000142-29. Registered on April 9, 2015; version 1.4

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2254-3) contains supplementary material, which is available to authorized users.

Localized neuropathic pain: an expert consensus on local treatments

BACKGROUND

Pain localization is one of the hallmarks for the choice of first-line treatment in neuropathic pain. This literature review has been conducted to provide an overview of the current knowledge regarding the etiology and pathophysiology of localized neuropathic pain (LNP), its assessment and the existing topical pharmacological treatments.

MATERIALS AND METHODS

Literature review was performed using Medline from 2010 to December 2016, and all studies involving LNP and treatments were examined. A multidisciplinary expert panel of five pain specialists in this article reports a consensus on topical approaches that may be recommended to alleviate LNP and on their advantages in clinical practice.

RESULTS

Successive international recommendations have included topical 5% lidocaine and 8% capsaicin for LNP treatment. The expert panel considers that these compounds can be a first-line treatment for LNP, especially in elderly patients and patients with comorbidities and polypharmacy. Regulatory LNP indications should cover the whole range of LNP and not be restricted to specific etiologies or sites. Precautions for the use of plasters must be followed cautiously.

CONCLUSION

Although there is a real need for more randomized controlled trials for both drugs, publications clearly demonstrate excellent risk/benefit ratios, safety, tolerance and continued efficacy throughout long-term treatment. A major advantage of both plasters is that they have proven efficacy and may reduce the risk of adverse events such as cognitive impairment, confusion, somnolence, dizziness and constipation that are often associated with systemic neuropathic pain treatment and reduce the quality of life. Topical modalities also may be used in combination with other drugs and analgesics with limited drug-drug interactions.

Paracetamol sharpens reflection and spatial memory: a double-blind randomized controlled study in healthy volunteers

Background

Acetaminophen (APAP, paracetamol) mechanism for analgesic and antipyretic outcomes has been largely addressed, but APAP action on cognitive function has not been studied in humans. Animal studies have suggested an improved cognitive performance but the link with analgesic and antipyretic modes of action is incomplete. This study aims at exploring cognitive tests in healthy volunteers in the context of antinociception and temperature regulation. A double-blind randomized controlled study (NCT01390467) was carried out from May 30, 2011 to July 12, 2011.

Methods

Forty healthy volunteers were included and analyzed. Nociceptive thresholds, core temperature (body temperature), and a battery of cognitive tests were recorded before and after oral APAP (2 g) or placebo: Information sampling task for predecisional processing, Stockings of Cambridge for spatial memory, reaction time, delayed matching of sample, and pattern recognition memory tests. Analysis of variance for repeated measures adapted to crossover design was performed and a two-tailed type I error was fixed at 5%.

Results

APAP improved information sampling task (diminution of the number of errors, latency to open boxes, and increased number of opened boxes; all P<0.05). Spatial planning and working memory initial thinking time were decreased (P=0.04). All other tests were not modified by APAP. APAP had an antinociceptive effect (P<0.01) and body temperature did not change.

Conclusion

This study shows for the first time that APAP sharpens decision making and planning strategy in healthy volunteers and that cognitive performance and antinociception are independent of APAP effect on thermogenesis. We suggest that cognitive performance mirrors the analgesic rather than thermic cascade of events, with possibly a central role for serotonergic and cannabinoid systems that need to be explored further in the context of pain and cognition.