Duloxetine in the management of chronic musculoskeletal pain

The analgesic effect and safety of duloxetine in total knee arthroplasty: A systematic review

Background: Duloxetine is a serotonin and norepinephrine reuptake inhibitor (SNRI) with clinical efficacy in chronic pain conditions. In this study, we aim to evaluate the analgesic effect and safety of duloxetine in total knee arthroplasty (TKA). Methods: A systematic search was completed on MEDLINE, PsycINFO, and Embase from inception to December 2022 to find relevant articles. We used Cochrane methodology to evaluate the bias of included studies. Investigated outcomes included postoperative pain, opioid consumption, adverse events (AEs), range of motion (ROM), emotional and physical function, patient satisfaction, patient-controlled analgesia (PCA), knee-specific outcomes, wound complications, skin temperature, inflammatory markers, length of stay, and incidence of manipulations. Results: Nine articles involving 942 participants were included in our systematic review. Out of nine papers, eight were randomized clinical trials and one was a retrospective study. The results of these studies indicated the analgesic effect of duloxetine on postoperative pain, which was measured using numeric rating scale and visual analogue scale. Deluxetine was also effective in reducing the morphine requirement and wound complications and enhancing patient satisfaction after surgery. However, the results on ROM, PCA, and knee-specific outcomes were contraventional. Deluxetine was generally safe without serious AEs. The most common AEs included headache, nausea, vomiting, dry mouth, and constipation. Conclusion: Duloxetine may be an effective treatment option for postoperative pain following TKA, but further rigorously designed and well-controlled randomized trials are required.

Effect of Preoperative Duloxetine Hydrochloride on Reducing Postoperative Morphine Requirement after Open Radical Cholecystectomy in Cancer Patients: A Randomized Controlled Study

Background

Recently, opoids are linked with cancer recurrence. Duloxetine hydrochloride (DH), an anxiolytic may reduce total opoid requirement after cancer surgery.

Aims

We assessed the efficacy of a single dose of DH in reducing the total morphine requirement after open radical cholecystectomy. We also calculated the Visual Analog Scale (VAS) score, patient satisfaction score (PSS), and time taken to the use of the first rescue analgesic.

Setting and Designes

This is a prospective, randomized, double blind, controlled study conducted in the patients aged 20-70 years (American Society of Anaesthesiologists classes I-III) undergoing open radical cholecystectomy under general anesthesia for carcinoma gall bladder.

Materials and Methods

The patients were divided into two groups of 32 patients each by computer-generated randomization. Group A received oral DH (60 mg); Group B received identical placebo capsules 2 h before surgery with a sip of water. Postoperatively, intravenous morphine was given using a patient-controlled analgesia pump. After 24 h, total morphine consumption, the VAS score, time to the first rescue analgesia, and PSS were recorded.

Statistical Analysis

Statistical Package for the Social Sciences software (SPSS version 22.0, IBM Corp., Chicago, IL, USA 2013). P value < 0.05 or 0.001 was considered statistically significant.

Results

The total morphine consumption and VAS score were significantly lower in Group A. No significant effects was observed on PSS.

Conclusion

A single 60 mg dose of DH administered 2 h before open radical cholecystectomy reduced total morphine consumption and improved VAS score postoperatively with no effect on PSS.

Efficacy of duloxetine in patients with knee osteoarthritis or chronic low back pain with early pain reduction: An exploratory post-hoc analysis of Japanese phase 3, 1-year extension studies

BACKGROUND

Two previous phase 3, double-blind, randomized, placebo-controlled trials showed that duloxetine 60 mg/day for 14 weeks significantly improved pain and quality of life in Japanese patients with knee osteoarthritis or chronic low back pain. In their open-label extension studies, these improvements were maintained for ≥48 weeks. This post-hoc analysis assessed the relationship between initial response to duloxetine and long-term pain reduction and quality of life in patients with knee osteoarthritis or chronic low back pain.

METHODS

Patients (knee osteoarthritis: N = 43; chronic low back pain: N = 41) were subdivided based on extent of pain reduction from baseline to Week 4 of duloxetine (≥30%, 10-30%, or <10% reduction in Brief Pain Inventory-Severity average pain score). Outcome measures were changes from baseline for Brief Pain Inventory-Severity and Brief Pain Inventory-Interference at regular intervals up to Week 65.

RESULTS

Mean change from baseline in Brief Pain Inventory-Severity was greater in patients with ≥30% early pain reduction than in patients with <10% early pain reduction through Week 27 for both conditions, and also Weeks 47-65 for back pain. Compared with the <10% early pain reduction group, mean change from baseline in the average of seven Brief Pain Inventory-Interference domain scores was greater in the ≥30% or 10-30% early pain reduction groups for knee osteoarthritis (except Weeks 63-65), and in the ≥30% early pain reduction group for chronic low back pain through Week 19.

CONCLUSIONS

These results suggest that patients with knee osteoarthritis who respond well to duloxetine in the first month might experience sustained, long-term pain relief with generally greater quality-of-life improvement than patients with poor initial response. Patients with chronic low back pain who had strong initial response may experience a greater long-term pain relief, but not greater quality-of-life improvement, than patients with poor initial response.

The relationship between mental health/physical activity and pain/dysfunction in working-age patients with knee osteoarthritis being considered for total knee arthroplasty: a retrospective study

BACKGROUND

Increasing total knee arthroplasty (TKA) surgeries are being performed on working-age patients with prominent manifestations of pain and dysfunction. But few studies have explored the risk factors for pain and dysfunction in working-age patients with knee osteoarthritis (KOA) being considered for TKA. Therefore, this study sought to explore the relationship between mental health/physical activity and pain/dysfunction in working-age patients with KOA being considered for TKA.

METHODS

This study was a secondary analysis of data derived from a public database, the Work participation In Patients with Osteoarthritis cohort study, which included 152 working-age patients (65 men and 87 women) with KOA planning for TKA. We analyzed preoperative data comprising age, educational level, body mass index (BMI), mental factors (Patient Health Questionnaire-9 [PHQ-9] and the 36-Item Short Form Survey Instrument [SF-36 mental health]), physical activity level, and clinical outcomes (the Western Ontario and McMaster Universities Osteoarthritis Index and SF-36 sub-item score). Multivariate regression analysis was performed to determine risk factors for pain and dysfunction in working-age patients with KOA being considered for TKA.

RESULTS

Women had lower pain, worse function, and higher PHQ-9 scores than men (p < 0.001). The depression scores were significantly linearly related to pain and function scores in women after adjusting for age, BMI, educational level, and physical activity (P < 0.05), whereas this relation was not observed in men. After adjusting for age, BMI, educational level, and mental factors, exercise time was found to be positively correlated with pain scores in women (P < 0.05).

CONCLUSIONS

Depression scores and exercise time were significantly correlated with pain and dysfunction in working-age women with KOA being considered for TKA.

Preemptive Duloxetine Relieves Postoperative Pain and Lowers Wound Temperature in Centrally Sensitized Patients Undergoing Total Knee Arthroplasty: A Randomized, Double-Blind, Placebo-Controlled Trial

(1) Background: The purpose of this study was to determine whether preemptive duloxetine in patients with central sensitization (CS) is effective for acute postoperative pain control and wound healing following total knee arthroplasty (TKA). (2) Methods: CS was defined as a score of 40 points or higher on the Central Sensitization Inventory (CSI) survey. Thirty-nine patients with CS were randomly assigned to either the duloxetine group (n = 19) or the placebo group (n = 20). The duloxetine group took duloxetine 30 mg once a day, while the placebo group took the placebo medication once a day. A pain visual analog scale (VAS) and the Brief Pain Inventory (BPI), wound complications, the temperature of the surgical site, and adverse events were investigated. Skin temperature was measured at the center of the patella using a portable digital thermometer. (3) Results: The duloxetine group reported significantly lower pain VAS scores during follow-up periods up to 6 weeks after surgery (all p < 0.05). BPI interference also showed significantly superior results in the duloxetine group after surgery (all p < 0.05). Although there was no difference in the rate of wound complications between the two groups (p > 0.05), the duloxetine group showed significantly lower wound temperature than the placebo group during the follow-up period (all p < 0.05). (4) Conclusion: In this study, preemptive duloxetine effectively reduced pain and lowered wound temperature following TKA in CS patients.

Efficacy of duloxetine for multisite pain in patients with knee pain due to osteoarthritis: An exploratory post hoc analysis of a Japanese phase 3 randomized study

BACKGROUND

Central sensitization, including dysfunction of descending inhibitory pain pathways, may contribute to multisite pain in patients with chronic musculoskeletal conditions. Duloxetine is a centrally acting analgesic that effectively reduces pain in patients with knee osteoarthritis. Here we assessed the efficacy of duloxetine (60 mg/day) in Japanese patients (N = 353) with pain due to knee osteoarthritis based on the number of painful body sites, determined using the Michigan Body Map.

METHODS

Post hoc analysis of a phase 3, randomized, placebo-controlled trial (ClinicalTrials.gov; NCT02248480).

RESULTS

At Week 14, the change from baseline in Brief Pain Inventory-Severity average pain score ("pain reduction") was significantly greater with duloxetine compared with placebo in patients with 3, 4, or ≥5 painful sites, but not in patients with 1 or 2 painful sites. In patients with ≥3 painful sites (57% of patients), pain reduction was significantly greater with duloxetine (n = 100) compared with placebo (n = 101) throughout the study (least squares mean change from baseline to Week 14: -2.68 vs -1.68). Greater pain reduction with duloxetine (n = 77) than placebo (n = 75) also occurred in patients with ≤2 painful sites, although the between-group difference was significant only at Week 4.

CONCLUSIONS

These results are consistent with duloxetine enhancing the activity of descending inhibitory pain pathways that are dysfunctional in patients with central sensitization and multisite pain. In addition, these results suggest that duloxetine may be an effective choice of analgesic for patients with knee osteoarthritis and multisite pain.

Drug Repositioning: New Approaches and Future Prospects for Life-Debilitating Diseases and the COVID-19 Pandemic Outbreak

Traditionally, drug discovery utilises a de novo design approach, which requires high cost and many years of drug development before it reaches the market. Novel drug development does not always account for orphan diseases, which have low demand and hence low-profit margins for drug developers. Recently, drug repositioning has gained recognition as an alternative approach that explores new avenues for pre-existing commercially approved or rejected drugs to treat diseases aside from the intended ones. Drug repositioning results in lower overall developmental expenses and risk assessments, as the efficacy and safety of the original drug have already been well accessed and approved by regulatory authorities. The greatest advantage of drug repositioning is that it breathes new life into the novel, rare, orphan, and resistant diseases, such as Cushing's syndrome, HIV infection, and pandemic outbreaks such as COVID-19. Repositioning existing drugs such as Hydroxychloroquine, Remdesivir, Ivermectin and Baricitinib shows good potential for COVID-19 treatment. This can crucially aid in resolving outbreaks in urgent times of need. This review discusses the past success in drug repositioning, the current technological advancement in the field, drug repositioning for personalised medicine and the ongoing research on newly emerging drugs under consideration for the COVID-19 treatment.

Targeting Pathological Tau by Small Molecule Inhibition of the Poly(A):MSUT2 RNA-Protein Interaction

Neurofibrillary tangles composed of aberrantly aggregating tau protein are a hallmark of Alzheimer's disease and related dementia disorders. Recent work has shown that mammalian suppressor of tauopathy 2 (MSUT2), also named ZC3H14 (Zinc Finger CCCH-Type Containing 14), controls accumulation of pathological tau in cultured human cells and mice. Knocking out MSUT2 protects neurons from neurodegenerative tauopathy and preserves learning and memory. MSUT2 protein functions to bind polyadenosine [poly(A)] tails of mRNA through its C-terminal CCCH type zinc finger domains, and loss of CCCH domain function suppresses tauopathy in Caenorhabditis elegans and mice. Thus, we hypothesized that inhibiting the poly(A):MSUT2 RNA-protein interaction would ameliorate pathological tau accumulation. Here we present a high-throughput screening method for the identification of small molecules inhibiting the poly(A):MSUT2 RNA-protein interaction. We employed a fluorescent polarization assay for initial small molecule discovery with the intention to repurpose hits identified from the NIH Clinical Collection (NIHCC). Our drug repurposing development workflow included validation of hits by dose-response analysis, specificity testing, orthogonal assays of activity, and cytotoxicity. Validated compounds passing through this screening funnel will be evaluated for translational effectiveness in future studies. This preclinical drug development pipeline identified diverse FDA approved drugs duloxetine, saquinavir, and clofazimine as potential repurposing candidates for reducing pathological tau accumulation.

Reduction in anxiety during treatment with exercise and duloxetine is related to improvement of low back pain-related disability in patients with non-specific chronic low back pain

Background:

Non-invasive treatment is generally recommended for patients with non-specific chronic low back pain (CLBP). However, the impact of combination therapy with physical exercise and a serotonin-norepinephrine reuptake inhibitor has not been clarified in patients with non-specific CLBP. This study assessed the efficacy of combination treatment with exercise and duloxetine on non-specific CLBP and aimed to identify factors that contributed to improvement of LBP-induced disability.

Methods:

This prospective study was conducted on consecutive outpatients with non-specific CLBP. Patients received a supervised home-based exercise program and duloxetine administration for 15 weeks. The Roland-Morris Disability Questionnaire (RDQ), Numerical Rating Scale (NRS), Hospital Anxiety and Depression Scale (HADS), and Pain Catastrophizing Scale (PCS) were assessed at baseline and 15 weeks. Multiple logistic regression modeling was used to identify factors associated with an improvement in RDQ.

Results:

Forty-two patients were enrolled. Overall, scores on the RDQ, NRS, and PCS (total score, magnification, helplessness) were significantly reduced at 15 weeks (p < 0.01 for all). An improvement of disability was confirmed in 22 patients (52%). A higher HADS depression score before and after the intervention was significantly associated with a lack of improvement in disability (p < 0.01). Further, a reduction in HADS anxiety score over 15 weeks was a significant factor associated with an improvement in disability (odds ratio: 1.99;95% CI: 1.26-3.65).

Conclusions:

Supervised exercise plus duloxetine resulted in favorable outcomes and an improvement of LBP-related disability in approximately 50% of patients. A reduction in anxiety over treatment was associated with the improved disability.

A Systematic Review of Efficacy, Safety, and Tolerability of Duloxetine

Duloxetine is a serotonin-norepinephrine reuptake inhibitor approved for the treatment of patients affected by major depressive disorder (MDD), generalized anxiety disorder (GAD), neuropathic pain (NP), fibromyalgia (FMS), and stress incontinence urinary (SUI). These conditions share parallel pathophysiological pathways, and duloxetine treatment might be an effective and safe alternative. Thus, a systematic review was conducted following the 2009 Preferred Reporting Items (PRISMA) recommendations and Joanna Briggs Institute Critical (JBI) Appraisals guidelines. Eighty-five studies focused on efficacy, safety, and tolerability of duloxetine were included in our systematic review. Studies were subdivided by clinical condition and evaluated individually. Thus, 32 studies of MDD, 11 studies of GAD, 19 studies of NP, 9 studies of FMS, and 14 studies of SUI demonstrated that the measured outcomes indicate the suitability of duloxetine in the treatment of these clinical conditions. This systematic review confirms that the dual mechanism of duloxetine benefits the treatment of comorbid clinical conditions, and supports the efficacy, safety, and tolerability of duloxetine in short- and long-term treatments.

Relationship Between Pain Alleviation and Disease-specific Health-related Quality of Life Measures in Patients With Chronic Low Back Pain Receiving Duloxetine: Exploratory Post Hoc Analysis of a Japanese Phase 3 Randomized Study

This post hoc analysis of a Japanese phase 3 randomized study (ClinicalTrials.gov identifier: NCT01855919) investigated relationships between pain severity (assessed by the Brief Pain Inventory [BPI]) and disease-specific health-related quality of life (assessed by the 24-item Roland-Morris Disability Questionnaire [RDQ-24]) in duloxetine-treated patients with chronic low back pain (CLBP).

Duloxetine and Angiotensin II Receptor Blocker Combination Potentially Induce Severe Hyponatremia in an Elderly Woman

We encountered a case of syndrome of inappropriate antidiuretic hormone secretion (SIADH) caused by duloxetine, serotonin and norepinephrine reuptake inhibitor (SNRI). A 74-year-old woman complaining of severe lethargy was transferred to our emergency department. Her serum sodium level was 109 mEq/L. Plasma hypo-osmolality with urine normo-osmolality was observed, indicating SIADH. Her essential hypertension had long been treated with telmisartan, and she had just started duloxetine 20 mg/day for chronic musculoskeletal pain 4 days prior to admission. On prescribing duloxetine in the primary care setting, clinicians should be aware of the possibility of duloxetine-induced hyponatremia, particularly in combination with telmisartan.

Efficacy of duloxetine by prior NSAID use in the treatment of chronic osteoarthritis knee pain: A post hoc subgroup analysis of a randomized, placebo-controlled, phase 3 study in Japan

BACKGROUND

A previously conducted placebo-controlled, randomized, phase 3 study of 353 Japanese patients with knee osteoarthritis (OA) showed significant improvements for duloxetine vs placebo in pain and health-related quality of life (HRQoL) (ClinicalTrials.gov Identifier: NCT02248480). Reported here are post hoc subgroup analyses evaluating the efficacy of duloxetine according to the pattern of prior nonsteroidal anti-inflammatory drug (NSAID) use.

METHODS

Patients with knee OA pain received once-daily duloxetine or placebo for 14 weeks. Pain was evaluated using the Brief Pain Inventory (BPI) and HRQoL was evaluated using the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). Patients were divided into four subgroups based on their prior NSAID use: (i) no prior NSAID use; (ii) low-frequency NSAID use (<14 days/month); (iii) high-frequency transdermal NSAID use (transdermal NSAIDs only; ≥14 days/month for the 3 months before study entry); and (iv) high-frequency other NSAID use (eg, oral NSAIDs only, both oral and transdermal NSAIDs; ≥14 days/month for the 3 months before study entry).

RESULTS

In each of the four prior NSAID use subgroups, there were greater reductions in BPI average pain severity score for duloxetine vs placebo at all timepoints during the 14-week treatment period; the treatment*prior NSAID use interaction was not statistically significant. In each subgroup, the proportion of patients achieving a ≥50% reduction in BPI average pain severity score was higher for duloxetine vs placebo. In each subgroup, there were greater reductions in WOMAC total score for duloxetine vs placebo at all timepoints; the treatment*prior NSAID use interaction was not statistically significant. In each subgroup, there were greater reductions at Week 14 in WOMAC pain, stiffness, physical function, and total scores for duloxetine vs placebo.

CONCLUSIONS

Duloxetine was consistently effective with respect to pain relief and HRQoL in Japanese patients with knee OA pain, regardless of the pattern of prior NSAID use.

Response to duloxetine in chronic low back pain: exploratory post hoc analysis of a Japanese Phase III randomized study

Purpose

Duloxetine is efficacious for chronic low back pain (CLBP). This post hoc analysis of a Japanese randomized, placebo-controlled trial (ClinicalTrials.gov, NCT01855919) assessed whether patients with CLBP with early pain reduction or treatment-related adverse events of special interest (TR-AESIs; nausea, somnolence, constipation) have enhanced responses to duloxetine.

Patients and methods

Patients (N = 456) with CLBP for ≥6 months and Brief Pain Inventory (BPI) average pain severity score of ≥4 were randomized (1:1) to duloxetine 60 mg/day or placebo for 14 weeks. Primary outcome was change from baseline in BPI average pain severity score (pain reduction). Subgroup analyses included early pain reduction (≥30%, 10%–30%, or <10% at Week 4) and early TR-AESIs (with or without TR-AESIs by Week 2). Measures included changes from baseline in BPI average pain severity score and BPI Interference scores (quality of life; QOL), and response rate (≥30% or ≥50% pain reduction at Week 14).

Results

Patients with ≥30% early pain reduction (n = 108) or early TR-AESIs (n = 50) had significantly greater improvements in pain and QOL than placebo-treated patients (n = 226), whereas patients with 10%–30% (n = 63) or <10% (n = 48) pain reduction did not; patients without early TR-AESIs (n = 180) had significant improvements in pain at Week 14. Response rates (≥30%/≥50% pain reduction) were 94.4%/82.4%, 66.7%/49.2%, and 25.0%/18.8% for patients with ≥30%, 10%–30%, and <10% early pain reduction, respectively, 74.0%/64.0% for patients with early TR-AESIs, 67.2%/54.4% for patients without early TR-AESIs, and 52.2%/39.4% for placebo.

Conclusion

Early pain reduction or TR-AESIs may predict which CLBP patients are most likely to respond to duloxetine with improvements in pain and QOL.

Duloxetine 60 mg for chronic low back pain: post hoc responder analysis of double-blind, placebo-controlled trials

Introduction

Duloxetine has demonstrated efficacy in chronic low back pain (CLBP). We examined the predictors of response to duloxetine for CLBP.

Patients and methods

This was a post hoc analysis of pooled data from 4 double-blind, ran-domized, placebo-controlled trials of duloxetine (60 mg/day for 12–14 weeks) in adult patients with CLBP. Primary outcome was proportion of patients with ≥30% reduction in Brief Pain Inventory (BPI) average pain (“pain reduction”) at 12–14 weeks. The proportion of patients with ≥30% and ≥50% (secondary outcome) pain reduction in duloxetine and placebo groups was compared. Variables for responder analyses were early improvement (≥15% pain reduction at Week 2), sex, age, baseline BPI average pain score, duration of CLBP, and number of painful body sites according to the Michigan Body Map (≥2 vs 1 [isolated CLBP]; 1 trial); relative risk (RR) and 95% confidence interval (CI) were calculated.

Results

Compared with placebo (n = 653), a greater proportion of duloxetine-treated patients (n = 642) achieved ≥30% (59.7% vs 47.8%; P < 0.001) and ≥50% pain reduction (48.6% vs 35.1%; P < 0.001). Among duloxetine-treated patients, early improvement was associated with greater likelihood of ≥30% (RR [95% CI], 2.91 [2.30–3.67]) or ≥50% (3.24 [2.44–4.31]) pain reduction. Women were slightly more likely than men to achieve ≥30% (RR [95% CI], 1.14 [1.00–1.30]) or ≥50% (1.17 [0.99–1.38]) pain reduction. Response rates were similar between age, CLBP duration, and baseline BPI average pain score subgroups. Patients with ≥2 painful sites were more likely to respond to duloxetine 60 mg relative to placebo than patients with isolated CLBP (RR, duloxetine vs placebo [95% CI]: ≥30% reduction, ≥2 painful sites 1.40 [1.18–1.66], isolated CLBP 1.07 [0.78–1.48]; ≥50% reduction, ≥2 painful sites 1.51 [1.20–1.89], isolated CLBP 1.23 [0.81–1.88]).

Conclusion

Early pain reduction was indicative of overall response. Patients with multiple painful sites had more benefit from duloxetine than patients with isolated CLBP.

Depression and chronic pain in the elderly: links and management challenges

Aging is an inevitable process and represents the accumulation of bodily alterations over time. Depression and chronic pain are highly prevalent in elderly populations. It is estimated that 13% of the elderly population will suffer simultaneously from the two conditions. Accumulating evidence suggests than neuroinflammation plays a critical role in the pathogenesis of both depression and chronic pain. Apart from the common pathophysiological mechanisms, however, the two entities have several clinical links. Their management is challenging for the pain physician; however, both pharmacologic and nonpharmacologic approaches are available and can be used when the two conditions are comorbid in the elderly patients.

Deconstructing Chronic Low Back Pain in the Older Adult: Step by Step Evidence and Expert-Based Recommendations for Evaluation and Treatment: Part IV: Depression

OBJECTIVE

To present the fourth in a series of articles designed to deconstruct chronic low back pain (CLBP) in older adults. The series presents CLBP as a syndrome, a final common pathway for the expression of multiple contributors rather than a disease localized exclusively to the lumbosacral spine. Each article addresses one of twelve important contributors to pain and disability in older adults with CLBP. This article focuses on depression.

METHODS

The evaluation and treatment algorithm, a table articulating the rationale for the individual algorithm components, and stepped-care drug recommendations were developed using a modified Delphi approach. The Principal Investigator, a three-member content expert panel, and a nine-member primary care panel were involved in the iterative development of these materials. The algorithm was developed keeping in mind medications and other resources available within Veterans Health Administration (VHA) facilities. As panelists were not exclusive to the VHA, the materials can be applied in both VHA and civilian settings. The illustrative clinical case was taken from one of the contributor's clinical practice.

RESULTS

We present an algorithm and supportive materials to help guide the care of older adults with depression, an important contributor to CLBP. The case illustrates an example of a complex clinical presentation in which depression was an important contributor to symptoms and disability in an older adult with CLBP.

CONCLUSIONS

Depression is common and should be evaluated routinely in the older adult with CLBP so that appropriately targeted treatments can be planned and implemented.

Behavioral pharmacology of pain

Behavioral methods are extensively used in pain research. Rodent modeling tends to rely on evoked responses but there is a growing interest in behavioral readouts that may capture elements of ongoing pain and disability, reflecting the major clinical signs and symptoms. Clinically, analgesics show greater efficacy in acute pain after standard surgery than in chronic conditions but are never completely effective on a population basis. In contrast, experimental pharmacological studies in rodents often demonstrate full efficacy, but there is variability in sensitivity between models and readouts. Full efficacy is rarely seen when more complex or multiple readouts are used to quantify behavior, especially after acute surgery or in studies of clinical pain in animals. Models with excellent sensitivity for a particular drug class exist and are suitable for screening mechanistically similar drugs. However, if used to compare drugs with different modes of action or to predict magnitude of clinical efficacy, these models will be misleading. Effective use of behavioral pharmacology in pain research is thus dependent on selection and validation of the best models for the purpose.

Myofascial pain syndrome: a treatment review

Myofascial pain syndrome (MPS) is defined as pain that originates from myofascial trigger points in skeletal muscle. It is prevalent in regional musculoskeletal pain syndromes, either alone or in combination with other pain generators. The appropriate evaluation and management of myofascial pain is an important part of musculoskeletal rehabilitation, and regional axial and limb pain syndromes. This article reviews the current hypotheses regarding the treatment modalities for myofascial trigger points and muscle pain. Through a critical evidence-based review of the pharmacologic and nonpharmacologic treatments, the authors aim to provide clinicians with a more comprehensive knowledge of the interventions for myofascial pain.