Treatment of chronic non-cancer pain

Endogenous Opioid-Masked Latent Pain Sensitization: Studies from Mouse to Human

Following the resolution of a severe inflammatory injury in rodents, administration of mu-opioid receptor inverse agonists leads to reinstatement of pain hypersensitivity. The mechanisms underlying this form of latent pain sensitization (LS) likely contribute to the development of chronic pain, but LS has not yet been demonstrated in humans. Using a C57BL/6 mouse model of cutaneous mild heat injury (MHI) we demonstrated a dose-dependent reinstatement of pain sensitization, assessed as primary (P < 0.001) and secondary hyperalgesia (P < 0.001) by naloxone (0.3–10 mg/kg), 168 hrs after the induction of MHI. Forward-translating the dose data to a human MHI model (n = 12) we could show that LS does indeed occur after naloxone 2 mg/kg, 168 hrs after a MHI. Our previous unsuccessful efforts to demonstrate unmasking of LS in humans are thus likely explained by an insufficient naloxone dose (0.021 mg/kg). However, while LS was consistently demonstrated in 21/24 mice, LS was only seen in 4/12 subjects. This difference is likely due to selection bias since the C57BL/6 mouse strain exhibits markedly enhanced pain sensitivity in assays of acute thermal nociception. Future exploratory studies in humans should prioritize inclusion of “high-sensitizers” prone to develop LS and use post-surgical models to elucidate markers of vulnerability to chronic postsurgical pain.

Prescribing Generic Medication in Chronic Musculoskeletal Pain Patients: An Issue of Representations, Trust, and Experience in a Swiss Cohort

Objective

Parallel to an ever stronger advocacy for the use of generics, various sources of information report concerns regarding substitution. The literature indicates that information regarding substitution is not univocal. The aim of this qualitative study was to explore patients’ representations regarding generics in patients suffering from non-specific disabling chronic musculoskeletal pain, as these patients are confronted with the issue of the prescription and/or substitution of original formulations with generics.

Methods

Qualitative methods were selected because the aim was to access the range of patients' representations and to consider their conceptions. Standardized face-to-face semi-structured interviews were used, and transcripts were submitted to content analysis.

Results

Patients’ representations suggest that they might be confident in taking a generic medication: when he/she has an understanding of generics as resulting from a development process that has become part of the public domain; the generic medication is prescribed by the physician; each prescription is discussed, i.e., the patient is prescribed the generic version of a given medication and not a generic medication.

Discussion

Economic arguments are not sufficient to justify substitution, and may even raise issues calling upon cognitive dissonance. Even in non-life-threatening diseases, negative cues require attention and need be de-emphasized - in particular lower price as an indication of lower quality, and generic status as contradictory with advocating individualization of medication.

Investigational sigma-1 receptor antagonists for the treatment of pain

INTRODUCTION

The sigma-1 receptor (σ1R) is a ligand-regulated molecular chaperone that interacts with other proteins, including NMDA and opioid receptors, to modulate their activity. Convergent evidence indicates that σ1R antagonists exert inhibitory effects (and agonists stimulatory effects) on pain by stepping down the intracellular signaling cascades involved in transduction of noxious stimuli and plastic changes (i.e., sensitization phenomena) associated with chronic pain states.

AREAS COVERED

This review addresses three primary domains. The first focuses on mechanisms underlying the antinociceptive effects of σ1R antagonists. The second addresses evidence gained using pharmacological tools and experimental drugs in the discovery phase and clinical development. Finally, the article outlines the potential benefits of σ1R antagonists, alone or in combination, in the context of available pain therapeutics.

EXPERT OPINION

There is a critical need for new analgesics based on new mechanisms of action. Target identification requires convincing evidence relating targets to function. In turn, target validation requires confirmation of therapeutic benefits, ideally in humans. Current preclinical evidence provides strong rationale for σ1R antagonists in pain. The outcome of clinical studies with the most advanced investigational σ1R antagonist, S1RA (E-52862), will be of great interest to ascertain the potential of this new therapeutic approach to pain management.

Chronic pain and health care spending: an analysis of longitudinal data from the Medical Expenditure Panel Survey

OBJECTIVE

To estimate average incremental health care expenditures associated with chronic pain by health care service category, expanding on prior research that focused on specific pain conditions instead of general pain, excluded low levels of pain, or did not incorporate pain duration.

DATA SOURCE

Medical Expenditure Panel Survey (MEPS) data (2008-2011; N = 26,671).

STUDY DESIGN

Differences in annual expenditures for adults at different levels of pain that interferes with normal work, as measured by the SF-12, were estimated using recycled predictions from two-part logit-generalized linear regression models.

PRINCIPAL FINDINGS

"A little bit" of chronic pain-related interference was associated with a $2,498 increase in total adjusted expenditures over no pain interference (p < .0001) and a $1,008 increase over nonchronic pain interference (p = .0001). Moderate and severe chronic pain-related interference was associated with a $3,707 and $5,804 increase in expenditures over no pain interference and a $2,218 and $4,315 increase over nonchronic interference, respectively (p < .0001). Expenditure increases were most pronounced for inpatient and hospital outpatient expenditures compared to other types of health care expenditures.

CONCLUSIONS

Chronic pain limitations are associated with higher health care expenditures. Results underscore the substantial cost of pain to the health care system.

Quantitative Evaluation of an Instrument to Identify Chronic Pain in HIV-Infected Individuals

A method to rapidly identify the presence of chronic pain would enhance the care of HIV-infected individuals, but such an instrument has not been assessed in this population to date. We assessed the construct validity of the two-question Brief Chronic Pain Questionnaire (BCPQ) in HIV-infected patients by assessing the association between BCPQ responses and known correlates of chronic pain. Participants in the University of Alabama Center for AIDS Research Network of Integrated Clinical Systems cohort completed the BCPQ, along with the EuroQOL to assess physical function, the PHQ-9 to assess depression, and the PHQ-anxiety module to assess anxiety. Among 100 participants, 25% were female, the mean age was 45 (SD 12), 63% were African American, 27% were publicly insured, the median CD4(+) T cell count was 572 cells/mm(3) (IQR 307-788), and 82% had an undetectable viral load. Participants with chronic pain were more likely to have impaired mobility (43% vs. 12%, p=0.001), difficulty with usual activities (47% vs. 12%, p<0.001), lower overall health state (70 vs. 84, p=0.002), pain today (80% vs. 27%, p<0.001), depression (30% vs. 15%, p=0.10), and anxiety (43% vs. 10%, p<0.001) than those without chronic pain. This study provides preliminary evidence for the BCPQ as a brief questionnaire to identify the presence of chronic pain in HIV care settings.

Interventions for the prediction and management of chronic postsurgical pain after total knee replacement: systematic review of randomised controlled trials

OBJECTIVES

Total knee replacement can be a successful operation for pain relief. However, 10-34% of patients experience chronic postsurgical pain. Our aim was to synthesise evidence on the effectiveness of applying predictive models to guide preventive treatment, and for interventions in the management of chronic pain after total knee replacement.

SETTING

We conducted a systematic review of randomised controlled trials using appropriate search strategies in the Cochrane Library, MEDLINE and EMBASE from inception to October 2014. No language restrictions were applied.

PARTICIPANTS

Adult patients receiving total knee replacement.

INTERVENTIONS

Predictive models to guide treatment for prevention of chronic pain. Interventions for management of chronic pain.

PRIMARY AND SECONDARY OUTCOME MEASURES

Reporting of specific outcomes was not an eligibility criterion but we sought outcomes relating to pain severity.

RESULTS

No studies evaluated the effectiveness of predictive models in guiding treatment and improving outcomes after total knee replacement. One study evaluated an intervention for the management of chronic pain. The trial evaluated the use of a botulinum toxin A injection with antinociceptive and anticholinergic activity in 49 patients with chronic postsurgical pain after knee replacement. A single injection provided meaningful pain relief for about 40 days and the authors acknowledged the need for a large trial with repeated injections. No trials of multidisciplinary interventions or individualised treatments were identified.

CONCLUSIONS

Our systematic review highlights a lack of evidence about the effectiveness of prediction and management strategies for chronic postsurgical pain after total knee replacement. As a large number of people are affected by chronic pain after total knee replacement, development of an evidence base about care for these patients should be a research priority.

Future implications of eHealth interventions for chronic pain management in underserved populations

SUMMARY 

Many underserved communities, especially those in rural settings, face unique challenges that make high quality healthcare less accessible. The implementation of eHealth technologies has become a potentially valuable option to disseminate interventions. The authors’ work in rural Alabama Federally Qualified Health Centers provide insights into the access to technology as well as the likelihood of utilizing eHealth technology in underserved communities. This paper will review current challenges related to digital dissemination of behavioral health interventions for chronic pain. Two major concerns are the lack of technological resources and the lack of appropriate materials for patients who may have low levels of reading, health and/or digital literacy. We will propose some recommendations to address common barriers faced by those providing care.

Attitudes and Beliefs of Working and Work-Disabled People with Chronic Pain Prescribed Long-Term Opioids

OBJECTIVE

This study was designed to gain insight into the apparent contradiction between the perspectives of researchers and policy makers, who have questioned the efficacy and safety of chronic opioid therapy for non-cancer pain patients, and the patients themselves, who often indicate that the therapy has value.

SUBJECTS

A convenience sample of 54 patients on chronic opioid therapy was studied.

METHODS

Participants completed a questionnaire specifically designed for the study, and also several standard instruments that addressed functional interference, emotional functioning, and possible misuse of opioids. Their treating physicians rated the participants on the severity of their disability and the success of their opioid therapy.

RESULTS

Although participants reported significant ongoing pain, they gave positive global ratings to their opioid therapy, and reported little concern about addiction or side effects of opioids. They strongly endorsed the beliefs that opioids helped them control their pain and allowed them to participate in important activities such as work. They expressed the belief that their pain would be severe if they did not have access to opioids, and reported negative experiences with tapering or discontinuing opioids in the past. Work-disabled participants reported higher levels of affective distress, catastrophizing, and functional interference than working participants, and were judged by their physicians to be relatively less successful in managing their pain.

CONCLUSION

The results of this study suggest several tentative hypotheses about why patients on chronic opioid therapy value opioids, and identified several areas for systematic investigation in the future.

Palliative care in the ambulatory geriatric practice

Geriatrics and palliative care often overlap. This article focuses on 2 areas where the disciplines may differ in their approach. The first is planning for extreme illness and death, with explicit acknowledgment that limiting therapy might be a good idea. This situation is likely to have a different impact in the course of a routine geriatrics visit than in a palliative care context. The second is pain management, especially chronic pain. In patients with sharply limited life expectancy, the risk/benefit equation tilts easily toward narcotic use. In frail elders working to remain independent, the calculus may be quite different.

Ziconotide Trialing by Intrathecal Bolus Injections: An Open-Label Non-Randomized Clinical Trial in Postoperative/Posttraumatic Neuropathic Pain Patients Refractory to Conventional Treatment

OBJECTIVES

The aim of this open-label, non-randomized, clinical trial was to evaluate the feasibility of trialing ziconotide by intrathecal bolus injections.

MATERIAL AND METHODS

Twenty-three patients, who had peripheral neuropathic pain refractory to pharmacological treatment and were under consideration for Spinal Cord Stimulation, received up to three ziconotide bolus injections according to a comprehensive algorithm. After a first injection of 2.5 μg, the patients progressed in the algorithm depending on the presence or absence of pain reduction and significant adverse events. A patient was considered a "responder" if experiencing pain reduction and no significant adverse event on two consecutive occasions at the same dosage.

RESULTS

We found a low proportion of responders (13%). However 30% of patients experienced ≥30% pain reduction on a least one injection, yielding a number needed to treat of ∼3 for clinically significant pain relief. Pain intensity changed significantly over time (0-6 h) (p = 0.047) after a mean ziconotide dose of 2.75 μg. Adverse events were as expected, and no serious adverse event occurred. We did not find any statistical association between response to Spinal Cord Stimulation and response to ziconotide.

CONCLUSIONS

Ziconotide bolus injection trialing seems feasible, but the proportion of responders in the present study was low. Adverse events were as expected, and no serious adverse event occurred. The predictive power of ziconotide bolus trialing remains unclear, and the pharmacological profile of ziconotide (slow tissue penetration due to high hydrophilicity) calls the rationale for bolus trialing into question.

The evolution of chronic opioid therapy and recognizing addiction

Chronic pain is one of the most common complaints in the United States. Opioids have become a frequently prescribed treatment for patients with chronic nonmalignant pain. Concurrently, opioid use disorders have risen to epidemic levels. Studies investigating iatrogenic opioid addiction have been of limited quality. Aberrant drug-related behaviors may be warning signs of impending addiction. Proper screening and close monitoring are essential for managing patients on opioids for chronic nonmalignant pain.

Pain in the Blood? Envisioning Mechanism-Based Diagnoses and Biomarkers in Clinical Pain Medicine

Chronic pain is highly prevalent, and pain medicine lacks objective biomarkers to guide diagnosis and choice of treatment. The current U.S. “opioid epidemic” is a reminder of the paucity of effective and safe treatment options. Traditional pain diagnoses according to the International Classification of Diseases are often unspecific, and analgesics are often prescribed on a trial-and-error basis. In contrast to this current state of affairs, the vision of future mechanism-based diagnoses of chronic pain conditions is presented in this non-technical paper, focusing on the need for biomarkers and the theoretical complexity of the task. Pain is and will remain a subjective experience, and as such is not objectively measurable. Therefore, the concept of “noci-marker” is presented as an alternative to “pain biomarker”, the goal being to find objective, measurable correlates of the pathophysiological processes involved in different chronic pain conditions. This vision entails a call for more translational pain research in order to bridge the gap between clinical pain medicine and preclinical science.

Efficacy and cost-effectiveness: A study of different treatment approaches in a tertiary pain centre

BACKGROUND

Chronic pain is considered to be a complex phenomenon, involving an interrelation of biological, psychosocial and sociocultural factors. Currently, no single treatment or therapy can address all aspects of this pathology. In our expert tertiary pain centre, we decide to assess the effectiveness of four treatments for chronic pain classically proposed in our daily clinical work: physiotherapy; psycho-education; physiotherapy combined with psycho-education; and self-hypnosis/self-care learning.

METHODS

This study included 527 chronic pain patients, with a mean duration of pain of 10 years. Patients were allocated either to one of the four pre-cited treatment groups or to the control group. Pain intensity, quality of life, pain interference, anxiety and depression were assessed before and after treatment.

RESULTS

This study revealed a significant positive effect on pain interference and anxiety in patients included in the physiotherapy combined with psycho-education group, after 20 sessions spread over 9 months of treatment. The most prominent results were obtained for patients allocated to the self-hypnosis/self-care group, although they received only six sessions over a 9-month period. These patients showed significant benefits in the areas of pain intensity, pain interference, anxiety, depression and quality of life.

CONCLUSIONS

This clinical report demonstrates the relevance of biopsychosocial approaches in the improvement of pain and psychological factors in chronic pain patients. The study further reveals the larger impact of self-hypnosis/self-care learning treatment, in addition to a cost-effectiveness benefit of this treatment comparative to other interventions.

Electroencephalography and analgesics

To assess centrally mediated analgesic mechanisms in clinical trials with pain patients, objective standardized methods such as electroencephalography (EEG) has many advantages. The aim of this review is to provide the reader with an overview of present findings in analgesics assessed with spontaneous EEG and evoked brain potentials (EPs) in humans. Furthermore, EEG methodologies will be discussed with respect to translation from animals to humans and future perspectives in predicting analgesic efficacy. We searched PubMed with MeSH terms 'analgesics', 'electroencephalography' and 'evoked potentials' for relevant articles. Combined with a search in their reference lists 15 articles on spontaneous EEG and 55 papers on EPs were identified. Overall, opioids produced increased activity in the delta band in the spontaneous EEG, but increases in higher frequency bands were also seen. The EP amplitudes decreased in the majority of studies. Anticonvulsants used as analgesics showed inconsistent results. The N-methyl-D-aspartate receptor antagonist ketamine showed an increase in the theta band in spontaneous EEG and decreases in EP amplitudes. Tricyclic antidepressants increased the activity in the delta, theta and beta bands in the spontaneous EEG while EPs were inconsistently affected. Weak analgesics were mainly investigated with EPs and a decrease in amplitudes was generally observed. This review reveals that both spontaneous EEG and EPs are widely used as biomarkers for analgesic drug effects. Methodological differences are common and a more uniform approach will further enhance the value of such biomarkers for drug development and prediction of treatment response in individual patients.

Psychosocial factors and central sensitivity syndromes

Central sensitivity syndromes (CSSs) represent a heterogeneous group of disorders (e.g., fibromyalgia [FM], irritable bowel syndrome [IBS], chronic headache, temporomandibular disorders [TMDs], pelvic pain syndromes) that share many common symptoms, with persistent pain being the most prominent feature. Although the etiology and pathophysiology of CSSs are currently incompletely understood, central sensitization has emerged as one of the significant mechanisms. Given that there are currently no known cures for CSSs, people living with these disorders must learn to cope with and manage their symptoms throughout their lives. Medical interventions alone have not proven to be sufficient for helping people with CSSs manage their symptoms. A biopsychosocial perspective that considers the ways that biological, psychological, and social factors work independently and jointly to affect a person's experience is the most effective conceptualization and guide for effective treatment. In this article, we discuss several psychological and social features that may influence the experience of a person with CSS and their symptom management, regardless of their specific diagnosis. We highlight the longitudinal aspect of adjustment to illness, the distinction between psychosocial factors as causes of symptoms versus modifiers and perpetuators of symptoms, dispel the notion that all patients with the same diagnosis are a homogeneous group (the "patient-uniformity myth"), and acknowledge the importance of environmental and situational context on symptom management for individuals with any CSS.

Denial of prescription analgesia among people who inject drugs in a Canadian setting

INTRODUCTION AND AIMS

Despite the high prevalence of pain among people who inject drugs (PWIDs), clinicians may be reluctant to prescribe opioid-based analgesia to those with a history of drug use or addiction. We sought to examine the prevalence and correlates of PWIDs reporting being denied of prescription analgesia (PA). We also explored reported reasons for and actions taken after being denied PA.

DESIGN AND METHODS

Using data from two prospective cohort studies of PWIDs, multivariate logistic regression was used to identify the prevalence and correlates of reporting being denied PA. Descriptive statistics were used to characterise reasons for denials and subsequent actions.

RESULTS

Approximately two-thirds (66.5%) of our sample of 462 active PWIDs reported having ever been denied PA. We found that reporting being denied PA was significantly and positively associated with having ever been enrolled in methadone maintenance treatment (adjusted odds ratio 1.76, 95% confidence interval 1.11-2.80) and daily cocaine injection (adjusted odds ratio 2.38, 95% confidence interval 1.00-5.66). The most commonly reported reason for being denied PA was being accused of drug seeking (44.0%). Commonly reported actions taken after being denied PA included buying the requested medication off the street (40.1%) or obtaining heroin to treat pain (32.9%).

DISCUSSION AND CONCLUSIONS

These findings highlight the challenges of addressing perceived pain and the need for strategies to prevent high-risk methods of self-managing pain, such as obtaining diverted medications or illicit substances for pain. Such strategies may include integrated pain management guidelines within methadone maintenance treatment and other substance use treatment programs.

Patients with chronic pain and dysphagia (CPD): unmet medical needs and pharmacologic treatment options

BACKGROUND

For properly selected patients experiencing chronic pain, extended-release opioid formulations may represent an appropriate pain management choice. For the many adults, elderly, and children who have medical conditions that make swallowing solid, oral-dose formulations difficult (dysphagia) or painful (odynophagia), this option may be limited. The combination of chronic pain with dysphagia (CPD) presents a challenge to physicians and patients alike when oral opioid analgesia is needed to control pain, but patients are unable to swallow solid, oral dosage forms.

METHODS

A Medline search was performed (1990 to 2013) using the search terms swallowing difficulties, dysphagia, odynophagia, adults, pediatrics, elderly, chronic pain, pain, and opioids. The following websites were searched: American Dysphagia Network, Dysphagia Research Society, World Health Organization, American Pain Society, International Association for the Study of Pain, American Academy of Pain Medicine, and American Society of Interventional Pain Physicians. Chronic pain guidelines from the following professional organizations were searched: American Pain Society, National Comprehensive Cancer Network, American Society of Interventional Pain Physicians, British Geriatric Society, European Society of Medical Oncology, World Health Organization, and the European Association for Palliative Care.

FINDINGS

There is an unmet medical need for greater recognition of dysphagia, awareness of potential problems with medication administration in these patients, recognition of alternative drug formulations that are available for use in CPD, and an appreciation that there are new, solid, oral-dose, opioid formulations in development that can mitigate these issues associated with swallowing difficulty while still providing practical, effective analgesia. Current pharmacologic treatments have limitations; new, prospective opioid formulations in clinical development may offer physicians and patients with CPD effective treatment options while mitigating accidental exposure and abuse liability.

CONCLUSIONS

The number of patients with CPD may be larger than is currently anticipated by healthcare providers. Physicians should proactively include a discussion of dysphagia as part of the patient examination. CPD is an unmet medical need. There are novel opioid formulations in clinical development that address the limitations of current opioid treatments. This manuscript reviews the problems associated with dysphagia on medication administration and adherence, currently available treatment options, and opioid analgesic formulations currently in clinical development.

P2X receptors: New players in cancer pain

Pain is unfortunately a quite common symptom for cancer patients. Normally pain starts as an episodic experience at early cancer phases to become chronic in later stages. In order to improve the quality of life of oncological patients, anti-cancer treatments are often accompanied by analgesic therapies. The P2X receptor are adenosine triphosphate (ATP) gated ion channels expressed by several cells including neurons, cancer and immune cells. Purinergic signaling through P2X receptors recently emerged as possible common pathway for cancer onset/growth and pain sensitivity. Indeed, tumor microenvironment is rich in extracellular ATP, which has a role in both tumor development and pain sensation. The study of the different mechanisms by which P2X receptors favor cancer progression and relative pain, represents an interesting challenge to design integrated therapeutic strategies for oncological patients. This review summarizes recent findings linking P2X receptors and ATP to cancer growth, progression and related pain. Special attention has been paid to the role of P2X2, P2X3, P2X4 and P2X7 in the genesis of cancer pain and to the function of P2X7 in tumor growth and metastasis. Therapeutic implications of the administration of different P2X receptor blockers to alleviate cancer-associated pain sensations contemporarily reducing tumor progression are also discussed.

Chronic Pain: Content Validation of Nursing Diagnosis in Slovakia and the Czech Republic

PURPOSE

The main purpose of the study was to validate the defining characteristics and related factors of the nursing diagnosis "chronic pain" in Slovakia and the Czech Republic.

METHODS

This is a descriptive study. The validation process involved was based on Fehring's Diagnostic Content Validity Model.

FINDINGS

Three defining characteristics (reports pain, altered ability to continue previous activities, and depression) were classified as major by Slovak nurses, and one defining characteristic (reports pain) was classified as major by Czech nurses.

CONCLUSION

The results of the study provide guidance in devising strategies of pain assessment and can aid in the formulation of accurate nursing diagnoses.

IMPLICATIONS FOR NURSING PRACTICE

The defining characteristic "reports pain" is important for arriving at the nursing diagnosis "chronic pain."

Sodium hydrosulfide relieves neuropathic pain in chronic constriction injured rats

Aberrant neuronal activity in injured peripheral nerves is believed to be an important factor in the development of neuropathic pain (NPP). Channel protein pCREB of that activity has been shown to mitigate the onset of associated molecular events in the nervous system, and sodium hydrosulfide (NaHS) could inhibit the expression of pCREB. However, whether NaHS could relieve the pain, it needs further experimental research. Furthermore, the clinical potential that NaHS was used to relieve pain was limited so it would be required. To address these issues, the rats of sciatic nerve chronic constriction injury (CCI) were given intraperitoneal injection of NaHS containing hydrogen sulfide (H₂S). The experimental results showed that NaHS inhibited the reduction of paw withdrawal thermal latency (PWTL), mechanical withdrawal threshold (MWT), and the level of pCREB in CCI rats in a dose-dependent manner and they were greatly decreased in NaHS_M group (P < 0.05). NaHS alleviates chronic neuropathic pain by inhibiting expression of pCREB in the spinal cord of Sprague-Dawley rats.

Ethnopharmacological analysis of medicinal plants and animals used in the treatment and management of pain in Mauritius

ETHNOPHARMACOLOGICAL RELEVANCE

Pain is a multi-faceted and multi-factorial condition which is challenging to manage and treat. Conventional therapies such as analgesics, Non-steroidal anti-inflammatory drugs (NSAIDs), and corticosteroids amongst others have been successful to some extent in its management and treatment. Nonetheless, such therapies tend to be accompanied by undesirable effects and have a limited therapeutic range. Consequently, there is a pressing need to probe for novel analgesic and anti-nociceptive drugs from traditional medicines (TM). This study was designed to record, document and analyze herbal and animal-based therapies used for the management and treatment of pain in the tropical of Mauritius.

MATERIALS AND METHODS

Data was collected via face-to-face interviews with TM users (n=332) and practitioners (n=20). Seven quantitative ethnopharmacological indexes, namely family use value (FUV), use value (UV), informant agreement ratio (IAR), relative frequency of citation (RFC), fidelity level (FL), relative importance (RI) and ethnobotanicity index (EI) were calculated.

RESULTS

A total of 79 plant species distributed within 40 families and 20 polyherbal preparations was recorded. Interestingly, 6 indigenous/endemic plants have been reported for the first time to be in common use for pain management and treatment in Mauritius. The most significant biologically important plant family was Xanthorrhoeaceae with highest FUV. The species which ranked highest according to its UV was Morinda citrifolia L. Morinda citrifolia L. and Ricinus communis L. also scored the highest RFC. The IAR values for the disease categories were high (0.95-0.97). Based on EI, plants species which are known to be useful in TM accounted for 11.5% of the total flora in Mauritius. Coix lacryma-jobi L. (FL=100%) had highest FL for lower back ache. Morinda citrifolia L. scored highest on most of the quantitative indices calculated including RI, which is endorsed by extensive documentation on its versatility and particularly its anti-nociceptive properties. Seven animal species were recorded to be in common use.

CONCLUSION

The present ethnopharmacological study revealed a panoply of TM to be in common use for pain management and treatment in Mauritius. This study has documented for the first time medicinal plants and animal species with potential analgesic and/or anti-nociceptive properties. This study has therefore provided important baseline primary data for the discovery of new lead molecules for drug development geared towards pain management and treatment.

Practical considerations and patient selection for intrathecal drug delivery in the management of chronic pain

Chronic pain continues to pose substantial and growing challenges for patients, caregivers, health care professionals, and health care systems. By the time a patient with severe refractory pain sees a pain specialist for evaluation and management, that patient has likely tried and failed several nonpharmacologic and pharmacologic approaches to pain treatment. Although relegated to one of the interventions of "last resort", intrathecal drug delivery can be useful for improving pain control, optimizing patient functionality, and minimizing the use of systemic pain medications in appropriately selected patients. Due to its clinical and logistical requirements, however, intrathecal drug delivery may fit poorly into the classic pain clinic/interventional model and may be perceived as a "critical mass" intervention that is feasible only for large practices that have specialized staff and appropriate office resources. Potentially, intrathecal drug delivery may be more readily adopted into larger practices that can commit the necessary staff and resources to support patients' needs through the trialing, initiation, monitoring, maintenance, and troubleshooting phases of this therapy. Currently, two agents - morphine and ziconotide - are approved by the United States Food and Drug Administration for long-term intrathecal delivery. The efficacy and safety profiles of morphine have been assessed in long-term, open-label, and retrospective studies of >400 patients with chronic cancer and noncancer pain types. The efficacy and safety profiles of ziconotide have been assessed in three double-blind, placebo-controlled trials of 457 patients, and safety has been assessed in 1,254 patients overall, with severe chronic cancer, noncancer, and acquired immunodeficiency syndrome pain types. Both agents are highlighted as first-line intrathecal therapy for the management of neuropathic or nociceptive pain. The purpose of this review is to discuss practical considerations for intrathecal drug delivery, delineate criteria for the identification and selection of candidates for intrathecal drug delivery, and consider which agent may be more appropriate for individual patients.

'Two pains together': patient perspectives on psychological aspects of chronic pain while living with HIV

OBJECTIVE

Chronic pain is common in HIV-infected individuals. Understanding HIV-infected patients' chronic pain experience not just from a biological, but also from a psychological perspective, is a critical first step toward improving care for this population. Our objective was to explore HIV-infected patients' perspectives on psychological aspects of chronic pain using in-depth qualitative interviews.

METHODS

Investigators engaged in an iterative process of independent and group coding until theme saturation was reached.

RESULTS

Of the 25 patients with chronic pain interviewed, 20 were male, 15 were younger than age 50, and 15 were African-American. Key themes that emerged included the close relationship between mood and pain; mood and pain in the context of living with HIV; use of alcohol/drugs to self-medicate for pain; and the challenge of receiving prescription pain medications while dealing with substance use disorders.

CONCLUSIONS

The results suggest that psychological approaches to chronic pain treatment may be well received by HIV-infected patients.

The pain interactome: connecting pain-specific protein interactions

Understanding the molecular mechanisms associated with disease is a central goal of modern medical research. As such, many thousands of experiments have been published that detail individual molecular events that contribute to a disease. Here we use a semi-automated text mining approach to accurately and exhaustively curate the primary literature for chronic pain states. In so doing, we create a comprehensive network of 1,002 contextualized protein-protein interactions (PPIs) specifically associated with pain. The PPIs form a highly interconnected and coherent structure, and the resulting network provides an alternative to those derived from connecting genes associated with pain using interactions that have not been shown to occur in a painful state. We exploit the contextual data associated with our interactions to analyse subnetworks specific to inflammatory and neuropathic pain, and to various anatomical regions. Here, we identify potential targets for further study and several drug-repurposing opportunities. Finally, the network provides a framework for the interpretation of new data within the field of pain.

Contribution of α,β-Amyrenone to the Anti-Inflammatory and Antihypersensitivity Effects of Aleurites moluccana (L.) Willd

The aim of the study was to analyze the constituents of the dichloromethane fraction obtained from A. moluccana and also to evaluate the anti-inflammatory and antinociceptive properties of α,β-amyrenone isolated from A. moluccana in mice. The dichloromethane fraction was evaluated by gas chromatography and submitted to purification. The mixture of α,β-amyrenone was isolated and then evaluated using the carrageenan-induced paw-oedema or pleurisy and CFA-induced arthritis models in mice. Five triterpenes, α,β-amyrenone, glutinol, and α,β-amyrin were isolated from dichloromethane fraction of A. moluccana leaf extract. The mixture of α,β-amyrenone, dosed orally, was able to reduce mechanical hypersensitivity and paw-oedema induced by carrageenan, interfering with neutrophil migration. Similar results were observed in the carrageenan-induced pleurisy model. Repeated administration of the compounds was also effective in reducing the mechanical sensitization and oedema developed in the arthritis model induced by CFA. In conclusion, the results demonstrate that α,β-amyrenone interferes in both acute and chronic inflammatory processes. We can infer that these effects involve, at least in part, a reduction in the neutrophil migration. Therefore, it seems reasonable to suggest that α,β-amyrenone could represent a new therapeutic tool for the management of painful and inflammatory diseases, especially those presenting a chronic profile.

Neurotrophins, endocannabinoids and thermo-transient receptor potential: a threesome in pain signalling

Because of the social and economic costs of chronic pain, there is a growing interest in unveiling the cellular and molecular mechanisms underlying it with the aim of developing more effective medications. Pain signalling is a multicomponent process that involves the peripheral and central nervous systems. At the periphery, nociceptor sensitisation by pro-inflammatory mediators is a primary step in pain transduction. Although pain is multifactorial at cellular and molecular levels, it is widely accepted that neurotrophin (TrkA, p75NTR, Ret and GFRs), cannabinoid (CB1 and CB2), and thermo-transient receptor potential (TRPs; TRPV1, TRPA1 and TRPM8) receptors play a pivotal role. They form a threesome for which endocannabinoids appear to be a first line of defence against pain, while neurotrophins and thermoTRPs are the major generators of painful signals. However, endocannabinoids may exhibit nociceptive activity while some neurotrophins may display anti-nociception. Accordingly, a clear-cut knowledge of the modulation and context-dependent function of these signalling cascades, along with the molecular and dynamic details of their crosstalk, is critical for understanding and controlling pain transduction. Here, the recent progress in this fascinating topic, as well as the tantalizing questions that remain unanswered, will be discussed. Furthermore, we will underline the need for using a systems biology approach (referred to as systems pain) to uncover the dynamics and interplay of these intricate signalling cascades, taking into consideration the molecular complexity and cellular heterogeneity of nociceptor populations. Nonetheless, the available information confirms that pharmacological modulation of this signalling triad is a highly valuable therapeutic strategy for effectively treating pain syndromes.

Predictors of multidisciplinary treatment outcome in patients with chronic musculoskeletal pain

PURPOSE

The present study aimed to identify predictors of rehabilitation outcome for patients with chronic musculoskeletal pain (CMP) and psychological problems.

METHODS

A retrospective cohort study including 230 adult patients with CMP admitted for multidisciplinary pain rehabilitation. Potential predictors were patient characteristics, duration of complaints, baseline functioning, pain, personality, coping style, fear of movement, psychological distress and type of treatment. Outcome measures were physical functioning, mental health, pain and patient-reported effect. Multiple (logistic) regression models were used to identify predictors.

RESULTS

Patients who were more disabled and patients with more pain benefitted more from the rehabilitation treatment than less disabled patients or those with less pain. Age, work status, vitality, depression and coping style also predicted outcomes significantly. The models explained between 27 and 80% of the outcomes. There was an interaction between type of treatment, work status and the baseline pain score as regards the outcome in terms of pain.

CONCLUSIONS

No strong predictors of treatment outcome were found other than the baseline scores of the respective outcome variables. More disabled patients and patients with more pain benefitted more from the rehabilitation program. Other predictors improved the prediction models slightly. Implications for Rehabilitation It remains challenging to correctly predict the outcome of treatment from patients' baseline sociodemographic and psychological characteristics; predictors other than baseline scores of the outcome variables are only slightly associated with treatment outcome. Patients with chronic musculoskeletal pain and poor physical functioning or mental health benefit most from pain rehabilitation. Older patients benefit less from a pain rehabilitation program than younger patients in terms of physical functioning. Pain reduction during a pain rehabilitation program is greatest in patients with high pain intensity who are not at work at the start of the rehabilitation program. Coping style influences the outcome of rehabilitation of patients with chronic musculoskeletal pain.

Development and pharmacological characterization of a model of sleep disruption-induced hypersensitivity in the rat

BACKGROUND

Sleep disturbance is a commonly reported co-morbidity in chronic pain patients, and conversely, disruption of sleep can cause acute and long-lasting hypersensitivity to painful stimuli. The underlying mechanisms of sleep disruption-induced pain hypersensitivity are poorly understood. Confounding factors of previous studies have been the sleep disruption protocols, such as the 'pedestal over water' or 'inverted flower pot' methods, that can cause large stress responses and therefore may significantly affect pain outcome measures.

METHODS

Sleep disruption was induced by placing rats for 8 h in a slowly rotating cylindrical cage causing arousal via the righting reflex. Mechanical (Von Frey filaments) and thermal (Hargreaves) nociceptive thresholds were assessed, and plasma corticosterone levels were measured (mass spectroscopy). Sleep disruption-induced hypersensitivity was pharmacologically characterized with drugs relevant for pain treatment, including gabapentin (30 mg/kg and 50 mg/kg), Ica-6p (Kv7.2/7.3 potassium channel opener; 10 mg/kg), ibuprofen (30 mg/kg and 100 mg/kg) and amitriptyline (10 mg/kg).

RESULTS

Eight hours of sleep disruption caused robust mechanical and heat hypersensitivity in the absence of a measurable change in plasma corticosterone levels. Gabapentin had no effect on reduced nociceptive thresholds. Ibuprofen attenuated mechanical thresholds, while Ica-6p and amitriptyline attenuated only reduced thermal nociceptive thresholds.

CONCLUSIONS

These results show that acute and low-stress sleep disruption causes mechanical and heat hypersensitivity in rats. Mechanical and heat hypersensitivity exhibited differential sensitivity to pharmacological agents, thus suggesting dissociable mechanisms for those two modalities. Ultimately, this model could help identify underlying mechanisms linking sleep disruption and hypersensitivity.

The feasibility and acceptability of groups for pain management in methadone maintenance treatment

OBJECTIVES

Effective and safe pain management interventions in methadone maintenance treatment are needed.

METHODS

We examined the feasibility (ie, single-session attendance) and acceptability (ie, patient satisfaction and booster session attendance) of cognitive-behavioral therapy-informed groups for pain management-Coping With Pain, Relaxation Training, Group Singing, and Mindful Walking. Pre- and postsession measures were collected.

RESULTS

A total of 349 (out of a census of approximately 800) methadone-maintained patients attended at least 1 of the groups. Group satisfaction was high. Booster session attendance was numerically lower in Mindful Walking (14%) than in the other groups (at least 40%). Repeat attendance at Coping With Pain was associated with reduced characteristic pain intensity and depression, whereas repeat attendance at Relaxation Training was associated with decreased anxiety.

CONCLUSIONS

Coping With Pain, Relaxation Training, and Group Singing are transportable, affordable, adaptable, and tolerated well by patients with pain and show promise as components of a multimodal pain management approach in methadone maintenance treatment.

Hypnotic approaches for chronic pain management: clinical implications of recent research findings

The empirical support for hypnosis for chronic pain management has flourished over the past two decades. Clinical trials show that hypnosis is effective for reducing chronic pain, although outcomes vary between individuals. The findings from these clinical trials also show that hypnotic treatments have a number of positive effects beyond pain control. Neurophysiological studies reveal that hypnotic analgesia has clear effects on brain and spinal-cord functioning that differ as a function of the specific hypnotic suggestions made, providing further evidence for the specific effects of hypnosis. The research results have important implications for how clinicians can help their clients experience maximum benefits from hypnosis and treatments that include hypnotic components.

The systematic implementation of acceptance & commitment therapy (ACT) in Dutch multidisciplinary chronic pain rehabilitation

OBJECTIVE

This study evaluates the implementation of Acceptance & Commitment Therapy (ACT) in Dutch chronic pain rehabilitation centers. Changes in multidisciplinary professionals' self-perceived competencies in working with ACT were evaluated and corroborated with patients' ratings of treatment adherence. To inform subsequent implementation efforts, relevant determinants of implementation success were monitored and the relationship with self-perceived competencies over time was explored.

METHODS

Data was gathered from 111 professionals, 9 managers and 79 patients using questionnaires at the start (T0), halfway (T1) and end (T2) of implementation, and at the end of treatment.

RESULTS

All professionals adhered to ACT, improved significantly in self-perceived competencies over time and rated competence in working with ACT ≥ adequate at T2. Determinants of success were evaluated extremely positive by professionals and management. Professionals' self-perceived competencies at T2 were most strongly related to ratings of more workload (b=-.43), and experienced difficulties in working with ACT (b=-.38) at T0 and T1.

CONCLUSION

Multidisciplinary chronic pain rehabilitation professionals rated their improvement in working with ACT positively during the implementation period. Impeding and facilitating factors were explored successfully.

PRACTICE IMPLICATIONS

A multi-faceted, long-term, educational, train-the-trainer approach may help to guide systematic changes in multidisciplinary treatment.

Analgesic efficacy of opioids in chronic pain: recent meta-analyses

Opioids are regularly administered in acute and cancer pain. In chronic non-cancer pain (CNCP), however, their use is controversial. Previous meta-analyses and randomized controlled trials (RCTs) lack methodological homogeneity and comparable data. Here we analysed the maximum analgesic efficacies of opioids and non-opioids compared with placebo, and of physiotherapy and psychotherapy compared with active or waiting-list controls. We screened 3647 citations and included RCTs if treatment duration was at least 3 weeks, data were sufficient for meta-analysis, and criteria for high quality were met. Only 46 studies (10 742 patients) met the criteria. Weighted and standardized mean differences (WMD, SMD) between pain intensities were pooled to conduct separate meta-analyses for each treatment category. At the end of treatment the WMD for pain reduction (100-point scale) was 12.0 for 'strong' opioids, 10.6 for 'weak' opioids, 8.4 for non-opioids (each vs. placebo), 5.5 for psychotherapy and 4.5 for physiotherapy (each vs. active controls). Dropout rates were high in pharmacological studies. The 95% confidence intervals using the outcomes of control groups did not indicate statistical differences between efficacies of the five interventions. Because not enough eligible head-to-head trials were available, our analysis is limited to adjusted indirect comparisons. The heterogeneity of pre-post pain differences in control groups did not allow the definition of a common comparator. In conclusion, although there were statistically significant differences between maximum treatment efficacies, no intervention per se produced clinically important improvements in average pain intensity. Thus, opioids alone are inappropriate and multimodal treatment programmes may be required for CNCP.

LINKED ARTICLES

This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.

Heterogeneous depression responses to chronic pain onset among middle-aged adults: a prospective study

Studies on depression response to chronic pain are limited by lack of clarification of different forms of response patterns and cross-sectional measures. The current study examined heterogeneous long-term patterns of depression response to chronic pain onset prospectively using the mixture modeling technique. Depression symptoms prior to and following pain onset over a course of six years were charted in a nationally representative middle-aged sample. Four distinct depression symptom trajectories emerged. The resilience (72.0%) trajectory describes a pattern of no/minimal depression symptoms prior to and following pain onset. The post-pain depression trajectory (11.4%) describes a pattern of low depression at baseline and increasing symptoms following pain onset. The chronic depression (6.8%) trajectory is characterized by persistently high depression symptoms irrespective of pain onset. The prior depression improved (9.8%) trajectory describes a pattern of high depression at baseline and gradually declining symptoms following pain onset. Self-rated health at both baseline and following pain onset predicted the resilience trajectory. Baseline self-rated health distinguished the post-pain depression and chronic depression trajectories. Individuals in the prior depression improved trajectory were older and had more chronic illnesses at baseline but fewer illnesses following pain onset, compared to those in the resilience or post-pain depression trajectory.

Prescribing opioids in primary care: avoiding perils and pitfalls

Millions of Americans have chronic pain for which chronic opioid therapy may be warranted. In light of recent abuse of these medications, clinicians must exercise caution and develop uniform approaches to prescribing. It is possible to assess for opioid risk and safely prescribe opioids.

Internet-based guided self-help intervention for chronic pain based on Acceptance and Commitment Therapy: a randomized controlled trial

Acceptance-based psychological interventions can potentially minimize the burden of chronic pain. This randomized controlled trial evaluated an internet-delivered, guided self-help intervention based on Acceptance and Commitment Therapy (ACT). A total of 238 chronic pain sufferers from the general population were randomly allocated to either ACT (n = 82), an internet-based control condition Expressive Writing (n = 79) or a waiting list condition (n = 77). Participants completed measures at baseline, posttreatment (3 months) and at a 3-month follow-up. At follow-up, ACT participants had improved in pain interference in daily life (primary outcome) compared to participants in Expressive Writing (Cohen's d = .47), but not compared to waiting list participants (p value = .11). Those who adhered to the ACT-intervention (48%) did improve significantly compared to waiting list participants (d = .49). ACT-participants also showed superior improvement on depression, pain intensity, psychological inflexibility and pain catastrophizing (d: .28-.60). Significant clinical improvement was present. Especially, 28% of ACT-participants showed general clinically relevant improvement in pain interference, as well as in pain intensity and depression (vs. Expressive Writing and waiting list 5%). Given these findings, internet-based ACT programs may be a promising treatment modality for chronic pain.

Selective sigma-1 receptor antagonists for the treatment of pain

The sigma-1 receptor (σ1R) is located in areas of the CNS key for pain control and belongs to a unique target class with chaperoning functions over different molecular targets involved in transmission and amplification of nociceptive messages. Preclinical evidence supports a role for σ1R antagonists in the treatment of pain states where hypersensitivity develops as hyperalgesia and allodynia, two common symptoms encountered in neuropathic and other chronic pain conditions. Additionally, σ1R antagonists increase opioid analgesia without increasing opioid-related unwanted effects, which point to their potential use as opioid adjuvant therapy. This review summarizes the structure and function of the σ1R as well as the medicinal chemistry and pharmacological studies directed to the identification of σ1R antagonists for the treatment of pain.

Synthesis and biological evaluation of a novel sigma-1 receptor antagonist based on 3,4-dihydro-2(1H)-quinolinone scaffold as a potential analgesic

The synthesis and sigma-1 receptor (σ1R) antagonist activity of a new series of 3,4-dihydro-2(1H)-quinolinone derivatives are reported. The new compounds were evaluated in vitro in sigma-1 and sigma-2 receptor-binding assays in guinea pig brain membranes. The structure-activity relationship led us to the promising derivative 7-(3-(piperidin-1-yl)propoxy)-1-(4-fluorobenzyl)-3,4-dihydro-2(1H)-quinolinone (35). The compounds with highest affinity and greatest selectivity were further profiled, and compound 35 had a high binding constant for sigma-1 receptor (Kiσ1 = 1.22 nM) and high sigma-1/2 selectivity (1066-fold). Thus, compound 35, which proved to be an antagonist of sigma-1 receptor, emerged as the most interesting candidate. In addition, compound 35 exerted dose-dependent anti-nociceptive effects in the formalin test. These characteristics suggested that the potent and selective compound 35 could be a potent candidate for pain treatment.

Pain and other symptoms in cancer survivors

Pain is common in cancer survivors. Long-term pain, often of neuropathic origin, is common after operations, radiotherapy, and chemotherapy. Pain and other concomitant symptoms and side effects should be assessed with validated and reliable scales and questionnaires. Cancer survivors with severe pain should be seen by a pain specialist. Multidisciplinary rehabilitation and individualized pain management may improve quality of life in cancer survivors. Four case reports are presented to illustrate this.

Self-management interventions for chronic pain

SUMMARY Individuals living with chronic pain face daily challenges of managing symptoms, modifying roles and responsibilities, and coping with the negative emotional consequences of pain. Self-management interventions teach a variety of strategies to meet these challenges and build participants' self-efficacy for their use. These interventions have been delivered in individual, group and online formats for a variety of different pain conditions. The evidence supports the efficacy of self-management interventions in improving pain, mental health and health-related quality of life outcomes. Acceptance of the chronic nature of their pain is a necessary step before individuals are ready to self-manage. Clinicians can play a critical role in supporting self-management through answering questions, providing advice, addressing barriers and facilitators, and encouraging self-management efforts.