Clinical experience with duloxetine in the management of chronic musculoskeletal pain. A focus on osteoarthritis of the knee

Effect of duloxetine on pain and opioid consumption after total knee and hip arthroplasty: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Although duloxetine has shown a positive effect on pain relief with hip and knee osteoarthritis, there is no pooled analysis of duloxetine for pain relief and opioid consumption in patients after total hip or knee arthroplasty.

AIM

This systematic review and meta-analysis aimed to analyze pain control, opioid consumption, and associated adverse events of perioperative administration of duloxetine after total hip or knee arthroplasty.

METHOD

After being registered with PROSPERO (CRD42022323202), the databases of MEDLINE, PubMed, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov were searched from inception until March 20, 2023, for randomized controlled trials (RCTs). Primary outcomes were the visual Analog Scale (VAS) pain scores at rest (rVAS) and upon ambulation (aVAS). Secondary outcomes were postoperative opioid consumption quantified as oral morphine milligram equivalents (MMEs) and adverse effects of duloxetine.

RESULTS

Nine RCTs with 806 cases were included. Duloxetine was associated with lower VAS scores at different times after surgery (24 h, two weeks, and ≥ 3 months). Compared to placebo, perioperative daily duloxetine use significantly reduced daily opioid MMEs at 24 h (standard mean deviation [SMD] -0.71, 95% confidence interval [95% CI] -1.19 to -0.24, P = 0.003), three days (SMD -1.10, 95% CI -1.70 to -0.50, P = 0.0003), and one week (SMD -1.18, 95% CI -1.99 to -0.38, P = 0.004) after surgery. The duloxetine group had a significantly lower rate of nausea (odds ratio 0.62, 95% CI [0.41 to 0.94], P = 0.02) and a higher rate of drowsiness and somnolence (odds ratio 1.87, 95% CI [1.13 to 3.07], P = 0.01) compared to the placebo group. No significant differences were observed in the rates of other adverse events.

CONCLUSION

 Perioperative duloxetine significantly decreased postoperative pain and opioid consumption with good safety profiles. Further high quality designed and well-controlled randomized trials are warranted.

Antidepressants for hip and knee osteoarthritis

BACKGROUND

Although pain is common in osteoarthritis, most people fail to achieve adequate analgesia. Increasing acknowledgement of the contribution of pain sensitisation has resulted in the investigation of medications affecting pain processing with central effects. Antidepressants contribute to pain management in other conditions where pain sensitisation is present.

OBJECTIVES

To assess the benefits and harms of antidepressants for the treatment of symptomatic knee and hip osteoarthritis in adults.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search was January 2021.

SELECTION CRITERIA

We included randomised controlled trials of adults with osteoarthritis that compared use of antidepressants to placebo or alternative comparator. We included trials that focused on efficacy (pain and function), treatment-related adverse effects and had documentation regarding discontinuation of participants. We excluded trials of less than six weeks of duration or had participants with concurrent mental health disorders.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Major outcomes were pain; responder rate; physical function; quality of life; and proportion of participants who withdrew due to adverse events, experienced any adverse events or had serious adverse events. Minor outcomes were proportion meeting the OARSI (Osteoarthritis Research Society International) Response Criteria, radiographic joint structure changes and proportion of participants who dropped out of the study for any reason. We used GRADE to assess certainty of evidence.

MAIN RESULTS

Nine trials (2122 participants) met the inclusion criteria. Seven trials examined only knee osteoarthritis. Two also included participants with hip osteoarthritis. All trials compared antidepressants to placebo, with or without non-steroidal anti-inflammatory drugs. Trial sizes were 36 to 388 participants. Most participants were female, with mean ages of 54.5 to 65.9 years. Trial durations were 8 to 16 weeks. Six trials examined duloxetine. We combined data from nine trials in meta-analyses for knee and hip osteoarthritis. One trial was at low risk of bias in all domains. Five trials were at risk of attrition and reporting bias. High-certainty evidence found that antidepressants resulted in a clinically unimportant improvement in pain compared to placebo. Mean reduction in pain (0 to 10 scale, 0 = no pain) was 1.7 points with placebo and 2.3 points with antidepressants (mean difference (MD) -0.59, 95% confidence interval (CI) -0.88 to -0.31; 9 trials, 2122 participants). Clinical response was defined as achieving a 50% or greater reduction in 24-hour mean pain. High-certainty evidence demonstrated that 45% of participants receiving antidepressants had a clinical response compared to 28.6% receiving placebo (RR 1.55, 95% CI 1.32 to 1.82; 6 RCTs, 1904 participants). This corresponded to an absolute improvement in pain of 16% more responders with antidepressants (8.9% more to 26% more) and a number needed to treat for an additional beneficial effect (NNTB) of 6 (95% CI 4 to 11). High-certainty evidence showed that the mean improvement in function (on 0 to 100 Western Ontario and McMaster Universities Arthritis Index, 0 = best function) was 10.51 points with placebo and 16.16 points with antidepressants (MD -5.65 points, 95% CI -7.08 to -4.23; 6 RCTs, 1909 participants). This demonstrates a small, clinically unimportant response. Moderate-certainty evidence (downgraded for imprecision) showed that quality of life measured using the EuroQol 5-Dimension scale (-0.11 to 1.0, 1.0 = perfect health) improved by 0.07 points with placebo and 0.11 points with antidepressants (MD 0.04, 95% CI 0.01 to 0.07; 3 RCTs, 815 participants). This is clinically unimportant. High-certainty evidence showed that total adverse events increased in the antidepressant group (64%) compared to the placebo group (49%) (RR 1.27, 95% CI 1.15 to 1.41; 9 RCTs, 2102 participants). The number needed to treat for an additional harmful outcome (NNTH) was 7 (95% CI 5 to 11). Low-certainty evidence (downgraded twice for imprecision for very low numbers of events) found no evidence of a difference in serious adverse events between groups (RR 0.94, 95% CI 0.46 to 1.94; 9 RCTs, 2101 participants). The NNTH was 1000.  Moderate-certainty evidence (downgraded for imprecision) showed that 11% of participants receiving antidepressants withdrew from trials due to an adverse event compared to 5% receiving placebo (RR 2.15, 95% CI 1.56 to 2.97; 6 RCTs, 1977 participants). The NNTH was 17 (95% CI 10 to 35).

AUTHORS' CONCLUSIONS

There is high-certainty evidence that use of antidepressants for knee osteoarthritis leads to a non-clinically important improvement in mean pain and function. However, a small number of people will have a 50% or greater important improvement in pain and function. This finding was consistent across all trials. Pain in osteoarthritis may be due to a variety of causes that differ between individuals. It may be that the cause of pain that responds to this therapy is only present in a small number of people. There is moderate-certainty evidence that antidepressants have a small positive effect on quality of life with heterogeneity between trials. High-certainty evidence indicates antidepressants result in more adverse events and moderate-certainty evidence indicates more withdrawal due to adverse events. There was little to no difference in serious adverse events (low-certainty evidence due to low numbers of events). This suggests that if antidepressants were being considered, there needs to be careful patient selection to optimise clinical benefit given the known propensity for adverse events with antidepressant use. Future trials should include alternative antidepressant agents or phenotyping of pain in people with osteoarthritis, or both.

High Prevalence of Pain Sensitization in Knee Osteoarthritis: A Meta-Analysis with Meta-Regression

OBJECTIVE

The aim of this meta-analysis was to study the evidence on pain sensitization in knee osteoarthritis (OA), providing a quantitative synthesis of its prevalence and impact. Factors associated with pain sensitization were also investigated.

METHODS

Meta-analysis; PubMed (MEDLINE), Cochrane Central Register (CENTRAL), and Web of Science were searched on February 2021. Level I to level IV studies evaluating the presence of pain sensitization in patients with symptomatic knee OA, documented through a validated method (questionnaires or quantitative sensory testing), were included. The primary outcome was the prevalence of pain sensitization. Factors influencing the prevalence were also evaluated, as well as differences in terms of pain thresholds between knee OA patients and healthy controls.

RESULTS

Fifty-three articles including 7,117 patients were included. The meta-analysis of proportion documented a prevalence of pain sensitization of 20% (95% confidence interval [CI] = 16%-26%) with a significant heterogeneity of results (I² = 89%, P < 0.001). The diagnostic tool used was the main factor influencing the documented prevalence of pain sensitization (P = 0.01). Knee OA patients presented higher pain sensitivity compared with healthy controls, both in terms of local pressure pain threshold (standardized mean difference [SMD] = -1.00, 95% CI = -1.67 to -0.32, P = 0.007) and distant pressure pain threshold (SMD = -0.54, 95% CI = -0.76 to -0.31, P < 0.001).

CONCLUSIONS

Knee OA pain presents features that are consistent with a significant degree of pain sensitization. There is a high heterogeneity in the reported results, mainly based on the diagnostic tool used. The identification of the best methods to detect pain sensitization is warranted to correctly evaluate and manage symptoms of patients affected by knee OA.

REGISTRATION

PROSPERO CRD42019123347.

Duloxetine in OsteoArthritis (DOA) study: effects of duloxetine on pain and function in end-stage hip and knee OA – a pragmatic enriched randomized controlled trial

Background

Some osteoarthritis (OA) patients experience inadequate pain relief from analgesics like acetaminophen and nonsteroidal anti-inflammatory drugs. This could be the result of experienced non-nociceptive centralized pain. Placebo-controlled randomized trials (RCT) have proven the effectiveness of duloxetine for OA and several chronic pain conditions where central sensitization (CS) is one of the key underlying pain mechanisms.

Objectives

Assess the efficacy of an 8-week duloxetine treatment compared to usual care in end-stage knee and hip OA patients with a level of centralized pain.

Design

Pragmatic, enriched, open-label RCT.

Methods

Patients were randomized to duloxetine or to care-as-usual. Primary outcome was pain in the index joint, measured with the pain domain of the Knee injury and Osteoarthritis Outcome Score (KOOS) or the Hip disability and Osteoarthritis Outcome Score (HOOS). The intention-to-treat principle was used, with mixed-model repeated measures to analyze the effect.

Results

One hundred eleven patients were randomized. Nearly 44% felt much to very much better after duloxetine usage compared to 0% in the care-as-usual group (p < 0.001). The duloxetine group scored 11.3 points (95%CI: 5.8, 16.8) better on the pain domain of the KOOS/HOOS (p < 0.001). Knee patients improved significantly more than hip patients (18.7 [95%CI: 11.3, 26.1] versus 6.0 [95%CI: − 2.6, 14.5] points better).

Conclusions

Adding duloxetine treatment seems to be beneficial for end-stage knee OA patients with neuropathic-like symptoms (at risk of CS). End stage Hip OA patients seem to be nonresponsive to duloxetine.

Trial registration

Dutch Trial Registry with number NTR 4744 (15/08/2014) and in the EudraCT database with number 2013–004313-41.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05034-0.

Effect of low-dose amitriptyline on reducing pain in clinical knee osteoarthritis compared to benztropine: study protocol of a randomised, double blind, placebo-controlled trial

Background

Knee osteoarthritis is a major cause of pain and disability. Pain control is poor, with most patients remaining in moderate to severe pain. This may be because central causes of pain, a common contributor to knee pain, are not affected by current treatment strategies. Antidepressants, such as amitriptyline, have been used to treat chronic pain in other conditions. The aim of this randomised, double blind, controlled trial, is to determine whether low dose amitriptyline reduces pain in people with painful knee osteoarthritis over 3 months compared to benztropine, an active placebo.

Methods/design

One hundred and sixty people with painful radiographic knee osteoarthritis will be recruited via clinicians, local and social media advertising. Participants will be randomly allocated in a 1:1 ratio to receive either low dose amitriptyline (25 mg) or active placebo (benztropine mesylate, 1 mg) for 3 months. The primary outcome is change from baseline in knee pain (WOMAC pain subscale) at 12 weeks. Secondary outcomes include change in function (total WOMAC) and the proportion of individuals achieving a substantial response (≥ 50% reduction in pain intensity, measured by Visual Analog Scale, VAS, from no pain to worst pain imaginable, 0-100 mm) and moderate response (≥ 30% reduction in pain intensity, measured by VAS) at 12 weeks. Intention to treat analyses will be performed. Subgroup analyses will be done.

Discussion

This study will provide high level evidence regarding the effectiveness of low dose amitriptyline compared to benztropine in reducing pain and improving function in knee OA. This trial has the potential to provide an effective new therapeutic approach for pain management in knee osteoarthritis, with the potential of ready translation into clinical practice, as it is repurposing an old drug, which is familiar to clinicians and with a well described safety record.

Trial registration

Australian New Zealand Clinical Trials Registry prior to recruitment commencing (ACTRN12615000301561, March 31, 2015, amended 14 December 2018, February 2021). Additional amendment requested 18 July 2021.

Correlation Between Gut Microbiome Composition and Acute Pain Perception in Young Healthy Male Subjects

OBJECTIVE

Recently, there has been growing interest in the gut-brain axis because it is emerging as a player influencing the health status of the host human. It is a known fact that the gut microbiome (GM) through the gut-brain axis has been implicated in numerous diseases. We previously reported that stool condition was associated with pain perception. Stool consistency and constipation are known to be associated with GM composition. Thus, we imagine that GM composition could influence pain perception. The aim of this study was to investigate the correlations between GM composition and pain perception and psychological states in young healthy male subjects.

SUBJECTS

A total of 42 healthy young male volunteers completed the present study.

METHODS

The volunteers' pain perceptions were assessed by pressure pain threshold, current perception threshold, temporal summation of pain, and conditioned pain modulation, and a questionnaire on psychological state was obtained. During the current perception threshold examination, we used 5, 250, and 2,000 Hz to stimulate C, Aδ, and Aβ fibers. In addition, GM composition was evaluated by using 16S rRNA analysis.

RESULTS

Pressure pain threshold showed a significant and negative correlation with Bacteroidetes phylum, in contrast to a significant and positive correlation with Firmicutes phylum. Current perception threshold of Aδ and Firmicutes phylum showed a significant correlation. There was a negative correlation between anxiety state and Bifidobacterium genus. In contrast, there was no significant correlation between psychological states and pain perceptions.

CONCLUSION

The present study showed that acute pain perception was associated with GM composition in young healthy males.

A treatment combined prussian blue nanoparticles with low-intensity pulsed ultrasound alleviates cartilage damage in knee osteoarthritis by initiating PI3K/Akt/mTOR pathway

Reactive oxidative stress (ROS) related apoptosis in chondrocytes and extracellular matrix (ECM) degradation play crucial roles in the process of osteoarthritis. Prussian blue nanoparticles are known to scavenge ROS in cellular. Low-intensity pulsed ultrasound has been used as a non-invasive modality for the is widely used in clinical rehabilitation management of OA. In this study, we aim to investigate the effects of PBNPs/LIPUS combined treatment on knee osteoarthritis (KOA) and to determine whether phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway mediates this process. Use LPS to process primary cells of knee joint cartilage to establish a cartilage knee arthritis model. After treated with LIPUS and PBNPs, cell viability was rated by CCK-8 and ROS levels were assessed by DCFH-DA. Articular pathological changes were observed by naked eyes, H&E, and Safranin O staining, then monitored by cartilage lesion grades and Mankin's score. Cellular ROS, apoptosis rate, and TUNEL staining of chondrocytes were fairly decreased in the PBNPs group and the LIPUS group but drastically down-regulated in the PBNPs/LIPUS combination treatment group when compared with the LPS group. Western blot results showed that the cleaved caspase-3, Bax, IL-1β, MMP3 and MMP13 in the PBNPs and LIPUS groups slightly decreased, and Bcl2 increased slightly, while in the combination treatment group, the former was significantly decreased, and Bcl2 was Significantly increased. The PBNPs/LIPUS combination treatment reduced cellular ROS, apoptosis, and matrix metalloproteinases (MMPs), as a consequence, alleviated articular cartilage damage in KOA. Moreover, the PBNPs/LIPUS combination treatment suppressed the JNK/c-Jun signal pathway.

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.

Genomic Medicine: Lessons Learned From Monogenic and Complex Bone Disorders

Current genetic studies of monogenic and complex bone diseases have broadened our understanding of disease pathophysiology, highlighting the need for medical interventions and treatments tailored to the characteristics of patients. As genomic research progresses, novel insights into the molecular mechanisms are starting to provide support to clinical decision-making; now offering ample opportunities for disease screening, diagnosis, prognosis and treatment. Drug targets holding mechanisms with genetic support are more likely to be successful. Therefore, implementing genetic information to the drug development process and a molecular redefinition of skeletal disease can help overcoming current shortcomings in pharmaceutical research, including failed attempts and appalling costs. This review summarizes the achievements of genetic studies in the bone field and their application to clinical care, illustrating the imminent advent of the genomic medicine era.

Intramuscular Pressure Is Almost Three Times Higher in Fibromyalgia Patients: A Possible Mechanism for Understanding the Muscle Pain and Tenderness

OBJECTIVE

Widespread pain in fibromyalgia syndrome (FMS) is conventionally viewed as arising from disordered central processing. This study examines intramuscular pressure in the trapezius as an alternative mechanism for understanding FMS pain.

METHODS

One hundred eight patients who satisfied the American College of Rheumatology criteria for FMS and 30 patients who met the ACR criteria for another rheumatic disease comprised the study groups. Muscle pressure was measured in mmHg using a pressure gauge attached to a no. 22 needle inserted into the mid-portion of the trapezius muscle. In addition, patients with FMS and rheumatic disease controls had dolorimetry testing, digital palpation, and reported pain scores.

RESULTS

Muscle pressure was substantially higher in patients with FMS with a mean value of 33.48 ± 5.90 mmHg. Only 2 of 108 patients had muscle pressure of < 23 mmHg. The mean pressure in rheumatic disease controls was 12.23 ± 3.75 mmHg, with a range from 3-22 mmHg. Patients with FMS were more tender than controls based on both dolorimetry (P < 0.001) and digital palpation (P < 0.001). The mean pain score in patients with FMS and controls was 6.68 ± 1.91 and 1.43 ± 1.79, respectively (P < 0.001).

CONCLUSION

Pressure in the trapezius muscle of patients with FMS is remarkably elevated and may be an intrinsic feature of FMS that could be monitored as part of the diagnostic evaluation. The burden of the pressure abnormality may help explain the diffuse muscle pain of FMS. Therefore, FMS as a disorder of exclusively central pain processing should be revisited. Therapeutically, the reduction of muscle pressure may change the clinical picture significantly.

Efficacy and safety of duloxetine in osteoarthritis or chronic low back pain: a Systematic review and meta-analysis

OBJECTIVE

To evaluate the efficacy and safety of duloxetine in the treatment of patients with osteoarthritis (OA) or chronic low back pain (CLBP).

METHODS

Relevant randomized controlled trials (RCTs) were searched in PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov. Included RCTs compared the efficacy and safety of duloxetine vs placebo in the treatment of OA or CLBP. Weighted mean difference (WMD) were calculated for continuous outcomes while risk ratio (RR) were calculated for dichotomous outcomes.

RESULTS

Nine RCTs were included in our meta-analysis. Duloxetine had significant improvement over placebo in Brief Pain Inventory 24-h average pain [WMD: -0.67; 95% confidence interval (CI):-0.80, -0.53], weekly mean of the 24-h average pain (WMD: -0.65; 95% CI: -0.79, -0.52), Patient's Global Impression of Improvement (WMD: -0.41; 95% CI: -0.49, -0.32), Clinical Global Impression of Severity (WMD: -0.32; 95% CI: -0.38, -0.25), European Quality of Life Questionnaire-5 Dimension (WMD: 0.04; 95% CI: 0.02, 0.07). In addition, duloxetine is associated with more treatment-emergent adverse events (TEAEs) (RR: 1.25; 95% CI: 1.17, 1.33) and discontinuations for adverse events (AEs) (RR: 2.31; 95% CI: 1.81, 2.94). However, there was no statistically significant difference in serious AEs between duloxetine and placebo.

CONCLUSION

Duloxetine had modest to moderate effects on pain relief, function improvement, mood regulation and improvement in quality of life with mild AEs in the treatment of OA or CLBP. Future RCTs should focus on comparing duloxetine with other oral drugs and assessing the long-term safety of duloxetine.

Osteoarthritis: Pathology, Diagnosis, and Treatment Options

Osteoarthritis (OA) is a worldwide endemic and debilitating disease. Previously thought to simply be damaged from "wear and tear," OA is now understood to be a complex interaction of local and systemic factors. This article reviews the pathology, symptoms, diagnosis, and various conservative, surgical, and novel treatments of OA.

Relationship Between Pain Reduction and Improvement in Health-Related Quality of Life in Patients with Knee Pain Due to Osteoarthritis Receiving Duloxetine: Exploratory Post Hoc Analysis of a Japanese Phase 3 Randomized Study

Purpose

This post hoc analysis of a Japanese phase 3 randomized study (ClinicalTrials.gov identifier: NCT02248480) investigated relationships between changes in pain severity and changes in health-related quality of life (HRQoL) in duloxetine-treated patients with knee osteoarthritis (OA).

Patients and Methods

Patients with knee OA and Brief Pain Inventory (BPI) average pain score ≥4 received duloxetine 60 mg/day or placebo for 14 weeks. Spearman rank correlation coefficients were calculated for change in pain severity, as assessed by the BPI, and change in HRQoL, as assessed by the items of the (i) 36-item Short-Form Health Survey (SF-36; a generic measure of HRQoL) and (ii) Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC; an OA-specific measure of HRQoL).

Results

After 14 weeks of treatment, there was a significantly greater improvement (p<0.001) for duloxetine (n=177) vs placebo (n=176) in BPI average pain severity score and significantly greater improvements (p<0.01) for duloxetine vs placebo for 5 of the 8 SF-36 domains (including the Role-Physical, Bodily Pain, and Physical Functioning domains) and all 24 individual WOMAC items. The correlation between BPI change from baseline and SF-36 item change from baseline was statistically significant (p<0.05) for 2 of the 8 SF-36 items (Bodily Pain, Physical Functioning) in duloxetine-treated patients. The correlation between BPI change from baseline and WOMAC item change from baseline was statistically significant for 22 of the 24 WOMAC items in duloxetine-treated patients.

Conclusion

This post hoc analysis suggested that the pain reduction observed in duloxetine-treated patients with knee OA was associated with improvements in OA-specific aspects of HRQoL, ie, pain and physical functioning.

Low-intensity pulsed ultrasound inhibits VEGFA expression in chondrocytes and protects against cartilage degeneration in experimental osteoarthritis

Low-intensity pulsed ultrasound (LIPUS), a noninvasive physical therapy, was recently demonstrated to be an effective treatment for osteoarthritis (OA). Vascular endothelium growth factor A (VEGFA) has been found to be upregulated in the articular cartilage, synovium and subchondral bone of OA patients, leading to cartilage degeneration, synovitis and osteophyte formation. However, the functions and mechanisms of LIPUS in regulating chondrocyte-derived VEGFA expression are still unclear. In this study, we investigated whether LIPUS attenuated OA progression by (a) decreasing the percentage of VEGFA-positive cells in mouse articular cartilage destabilised through medial meniscus surgery and (b) relieving interleukin-1β-induced VEGFA expression in mouse primary chondrocytes. However, this function was negated by a p38 mitogen-activated protein kinase (p38 MAPK) inhibitor. In addition, we found that LIPUS ameliorated VEGFA-mediated disorders in cartilage extracellular matrix metabolism and chondrocyte hypertrophy during OA development. In conclusion, our data indicate a novel effect of LIPUS in regulating the expression of osteoarthritic chondrocyte-derived VEGFA through the suppression of p38 MAPK activity.

The Clinical Relevance of Pain Severity Changes: Is There Any Difference Between Asian and Caucasian Patients With Osteoarthritis Pain?

The objective of the present analysis was to determine whether changes in Brief Pain Inventory (BPI) average pain scores by patient global impression of improvement (PGI‐I) category and the cut‐off for clinically important difference (CID) were different between Asian and Caucasian patients with chronic pain due to osteoarthritis. This analysis used data from 3 (Caucasian) and 2 (Asian) randomized, placebo‐controlled, 10‐ to 14‐week duloxetine studies for the treatment of patients ≥40 years of age with osteoarthritis pain. The receiver operating characteristic (ROC) analysis was used to characterize the association between changes in BPI average pain scores and PGI‐I levels at study endpoint. The CID was characterized by PGI‐I, and the cut‐off point for CID in BPI average pain scores was determined by the intersection of a 45‐degree tangent line with each ROC curve. Data from 668 Asian and 868 Caucasian patients were available for analysis. Baseline BPI average pain ratings including worst and least pain were comparable between Asians and Caucasians. Ratings for percentage change from baseline to endpoint for BPI average pain scores in Asian patients and Caucasian patients were similar across the 7 PGI‐I categories, regardless of age, gender, study, and treatment. The ROC analysis results of cut‐off points in BPI average pain scores demonstrated the raw change cut‐off was −3.0, and percentage change cut‐off was −40% for both Asian and Caucasian patients. Overall, the present analysis concludes changes in BPI average pain scores by PGI‐I category and the cut‐off for CID were similar for Asian and Caucasian patients with chronic pain due to osteoarthritis.

A Randomized, Double-Blind, Placebo- and Active Comparator-Controlled Phase I Study of Analgesic/Antihyperalgesic Properties of ASP8477, a Fatty Acid Amide Hydrolase Inhibitor, in Healthy Female Subjects

Objectives

To evaluate the analgesic/antihyperalgesic effect of ASP8477.

Design

Randomized, double-blind, double-dummy, cross-over, placebo- and active comparator-controlled study.

Setting

HPR Dr. Schaffler GmbH, Munich, Germany.

Subjects

Healthy female subjects aged 18–65 years.

Methods

Eligible subjects were randomly assigned to one of six treatment sequences and received multiple ascending doses of ASP8477, duloxetine, and placebo over three treatment periods (each consisting of 21-day dosing separated by 14-day washout periods). On the last day of each dose level, laser evoked potentials (LEPs) and visual analog scales (VAS pain) on capsaicin-treated skin at baseline and at multiple postdose time points were assessed. The primary end point was the difference in LEP N2-P2 peak-to-peak (PtP) amplitudes for ASP8477 100 mg vs placebo.

Results

Twenty-five subjects were randomized. In all subjects, LEP N2-P2 PtP amplitudes were numerically lower for ASP8477 100 mg vs placebo (P = 0.0721); in subjects who demonstrated positive capsaicin skin effects, a greater mean difference of –2.24 µV (P = 0.0146) was observed. Across all doses, LEP N2-P2 PtP amplitudes were lower for duloxetine compared with ASP8477 (mean difference –3.80 µV; P < 0.0001) or placebo (mean difference –5.21 µV; P < 0.0001). The effect of ASP8477 (all doses) on down-scoring the VAS pain score was significant compared with placebo (mean difference –2.55%; P < 0.0007).

Conclusions

ASP8477 was well tolerated in this study. Analysis of all subjects did not demonstrate a significant difference in LEP for ASP8477 100 mg over placebo but did in subjects who demonstrated positive capsaicin skin effects.

Work-related outcomes in randomized, double blind, placebo-controlled trials in osteoarthritis - are they adequately reported in journal publications? A systematic review

Background

Osteoarthritis (OA) has a high prevalence in Western societies and can affect an individual's life in a number of domains, including work. In our experience, treatment trials on OA, however, rarely report work-related outcomes. Here we conducted a systematic review to assess the reporting of work-related outcomes in randomized, double blind, placebo-controlled trials in OA. Our systematic review also compared two search strategies for identifying eligible publications, one where work-related terms were included in the database search string (A) and one where this was not the case and work-related outcomes were identified by searches of full text Portable Document Formats (PDFs) (B). Search strategy A would conventionally be used and would only identify publications where work-related terms were mentioned in the title or abstract. Search strategy B presents the innovation of full text PDF searching and would identify publications were work-related terms were reported in the full text, regardless of whether they are mentioned in the title and abstract or not. We hypothesize that search strategy B identifies more relevant publications than search strategy A.

Methods

Electronic database searching was performed in Medline (Pubmed) from database inception to February 23, 2017 to identify peer-reviewed articles of randomized, double blind, placebo-controlled treatment trials in OA of the hand, hip, or knee, available as full-text PDFs. For search strategy A, search terms to identify work-related outcomes were included in the database search string, while search strategy B did not have these terms included in the database search string, but instead involved full text PDF searching. We included English language articles only and only those articles where searchable PDFs were available, to enable a comparison between search strategies A and B. Additionally, included studies also needed to report on pain intensity in relation to the work-related outcomes.

Results

Search strategy A yielded 50 hits combined for hand, hip or knee OA that mentioned some work-related concept in the title or abstract; 12 articles had to be excluded because they were not available as searchable PDFs. Screening of the remaining 38 articles resulted in only two articles that satisfied our inclusion criteria. Search strategy B yielded 986 hits, out of which 201 articles were excluded because searchable full text PDFs were not available. PDF full text searching and further screening resulted in 10 articles that were considered eligible for our review.

Conclusions

Work-related outcomes are rarely reported in journal publication on randomized, double blind, placebo-controlled trials of hand, hip or knee OA. Searching full text PDFs yields more eligible articles than searching titles and abstracts only.

Association between serotonin-norepinephrine reuptake inhibitors and acute angle closure: What is known?

Serotonin-norepinephrine reuptake inhibitors are widely used antidepressants with a relatively safe profile. One of the complications associated with this group of drugs is acute angle closure. The mechanisms linking serotonin-norepinephrine reuptake inhibitors and acute angle closure are complex and may be interlinked with the effects of the drug on the inhibition of serotonin and noradrenaline reuptake, as well as pseudo-anticholinergic effects, dopaminergic effects, and idiosyncratic reactions with the drug molecule in the eye. Individual characteristics, such as polymorphisms of the gene encoding the 2D6 subunit of cytochrome P450, may affect the metabolism of the serotonin-norepinephrine reuptake inhibitor, whereas the combination with other drugs may lead to an increased risk of iridocorneal angle closure and may further exacerbate other mechanisms. Improved knowledge of the mechanisms linking serotonin-norepinephrine reuptake inhibitors and acute angle closure and of the risk factors predisposing to patients to acute angle closure will reduce the number of patients affected by this dangerous complication.

2017 update of the Turkish League Against Rheumatism (TLAR) evidence-based recommendations for the management of knee osteoarthritis

In a Turkish League Against Rheumatism (TLAR) project, evidence-based recommendations for the management of knee osteoarthritis (OA) was developed for the first time in our country in 2012 (TLAR-2012). In accordance with developing medical knowledge and scientific evidence, recommendations were updated. The committee was composed of 22 physical medicine and rehabilitation specialists (4 have rheumatology subspeciality also) and an orthopaedic surgeon. Systematic literature search were applied on Pubmed, Embase, Cochrane and Turkish Medical Index for the dates between January the 1st 2012 and January the 29th of 2015. The articles were assessed for quality and classified according to hierarchy for the level of evidence, and the selected ones sent to committee members electronically. They were asked to develop new recommendations. In the meeting in 2015, the format of the recommendations was decided to be patient-based and considering the grade and the severity of the disease. By the discussion of the each item under the light of new evidences, the final recommendations were developed. Each item was voted electronically on a 10-cm visual analogue scale (VAS) and the strength of recommendation (SoR) was calculated. In the light of evidences, totally 11 titles of recommendations were developed; the first 7 were applicable to each patient in every stages of the disease, remaining were for defined specific clinical situations. The mean SoR value of the recommendations was between 7.44 and 9.93. TLAR-2012 recommendations were updated in a new format. We think that, present recommendations will be beneficial for the physicians who manage, as well as the patients who suffer from the disease.

[Pharmacological treatment of osteoarthritis-related pain]

Joint pain due to osteoarthritis (OA) is often severe and disabling and affects a large proportion of the aging population impairing daily living and quality of life. Numerous pharmacological treatment approaches are available. Including major OA guidelines this review presents the current evidence of pharmacological therapies in OA-related pain and covers topical, oral and intraarticular treatment approaches. In patients with mild OA topical nonsteroidal antiinflammatory drugs (NSAIDs) can be recommended. Topical capsaicin can be used when other treatments are ineffective or contraindicated. In patients with moderate to severe OA oral NSAIDs are suggested at the lowest effective dose for the shortest possible duration to control symptoms. Importantly, drug-related side effects and gastrointestinal, cardiovascular and renal comorbidities need to be taken into account. In patients with multiple-joint OA and high risk of NSAID-induced adverse events duloxetine can be considered. The evidence of metamizole, symptomatic slow-acting drugs in osteoarthritis and other nutritional supplements in the treatment of OA pain is uncertain and the use of opioids is not routinely recommended. In patients suffering from severe OA-related pain intraarticular injections with glucocorticoids can be suggested to achieve short-term pain relief. Evidence for interventional approaches using hyaluronic acid or platelet-rich plasma is uncertain. Yet, the efficacy of pharmacological therapies in OA-related pain is often inconsistent and severe adverse events might occur. Thus, critical use of the different treatment options considering patient-related comorbidities and nonpharmacological therapies is of major importance.

Measuring and realizing the translational significance of preclinical in vivo studies of painful osteoarthritis

In this communication, we discuss some key issues surrounding the translation of preclinical efficacy studies in models of painful osteoarthritis (OA) to the clinical arena. We highlight potential pitfalls which could negatively impact successful translation. These include lack of alignment between a model + endpoint and the intended clinical population, employing testing strategies in animals that are not appropriate for the targeted human population such as pre-emptive treatment and lastly, underestimating the magnitude of the efficacy signal in animals that may be needed to see an effect in the clinical population. Through careful analysis, we highlight the importance of each pitfall by providing relevant examples that will hopefully improve future chances of optimizing translation in the area of OA pain research. We advocate advancing publications directed at comparing methods, outcomes and conclusions between preclinical and clinical studies, regardless of whether the findings are positive or negative, are important for improving the potential for a desired successful translation from the bench to bedside.

Investigation of the predictive validity of laser-EPs in normal, UVB-inflamed and capsaicin-irritated skin with four analgesic compounds in healthy volunteers

AIMS

The aim of the present study was to assess the predictivity of laser-(radiant-heat)-evoked potentials (LEPs) from the vertex electroencephalogram, using an algesimetric procedure, testing the anti-nociceptive/anti-hyperalgesic effects of single oral doses of four marketed analgesics (of different compound classes) vs. placebo, in healthy volunteers with three skin types.

METHODS

This was a randomized, placebo-controlled, single-blind, five-way-crossover trial. Twenty-five healthy male/female Caucasians were included (receiving celecoxib 200 mg, pregabalin 150 mg, duloxetine 60 mg, lacosamide 100 mg or placebo) in a Williams design, with CO₂ laser-induced painful stimuli to normal, ultraviolet (UV) B-inflamed and capsaicin-irritated skin. LEPs and visual analogue scale ratings were taken at baseline and hourly for 6 h postdose from all three skin types.

RESULTS

In normal skin, the averaged postdose LEP peak-to-peak-(PtP)-amplitudes were reduced by pregabalin (-2.68 μV; 95% confidence interval (CI) -4.16, 1.19) and duloxetine (-1.73 μV; 95% CI -3.21, -0.26) but not by lacosamide and celecoxib vs. placebo. On UVB-irradiated skin, reflecting inflammatory pain, celecoxib induced a pronounced reduction in LEP PtP amplitudes vs. placebo (-6.2 μV; 95% CI -7.88, -4.51), with a smaller reduction by duloxetine (-4.54 μV; 95% CI -6.21, -2.87) and pregabalin (-3.72 μV; 95% CI -5.40, -2.04), whereas lacosamide was inactive. LEP PtP amplitudes on capsaicin-irritated skin, reflecting peripheral/spinal sensitization, as in neuropathic pain, were reduced by pregabalin (-3.78 μV; 95% CI -5.31, -2.25) and duloxetine (-2.32 μV; 95% CI -3.82, -0.82) but not by celecoxib or lacosamide vs. placebo, which was in agreement with known clinical profiles. Overall, PtP amplitude reductions were in agreement with subjective ratings.

CONCLUSIONS

LEP algesimetry is sensitive to analgesics with different modes of action and may enable the effects of novel analgesics to be assessed during early clinical development.

Supraspinal Projection of Serotonergic and Noradrenergic Pathways Modulates Nociceptive Transmission in the Lower Urinary Tract of Rats

OBJECTIVES

To investigate the effect of descending serotonergic and noradrenergic pathways on nociception in the lower urinary tract (LUT).

METHODS

Female Sprague-Dawley rats were used. Following intraperitoneal administration of Vehicle or Milnacipran (30 mg/kg), which is one of serotonin-noradrenaline reuptake inhibitors (SNRI), 0.1% AA was infused into the bladder in normal (n = 4, each) and spinal cord injury (SCI) (n = 4, each) rats for 2 h on consciousness, and c-Fos, 5-HT and DβH were stained using immunohistochemistry at the L6 spinal cord as spinal areas associated with LUT.

RESULTS

In SCI rats, 5-HT or DβH-positive fibers were not observed at the L6 spinal cord, while there were many 5-HT and DβH-positive fibers in normal rats. The total number of c-Fos-positive cells was significantly increased in SCI rats compared to Normal rats (209.4 ± 7.1 in Normal, 336.4 ± 28.9 in SCI, P < 0.05), which indicated that interruption of supraspinal modulation enhances nocieptive transmission in the LUT. Regarding the effect of Milnacipran administration, the number of c-Fos-positive cells was significantly decreased at all region of the L6 spinal cord in normal rats (P < 0.05), while this reduction was not observed in SCI rats. This result demonstrated that administration of SNRI attenuates nocieptive transmission in the LUT, indicating that 5-HT and noradrenaline work as mediators of endogenous analgesic mechanisms through the supraspinal descending pain pathways.

CONCLUSIONS

Supraspinal projections of descending serotonergic and noradrenergic pathways to the lower lumbar spinal cord modulate nocieptive transmission in the LUT. Administration of SNRI attenuates nocieptive transmission in the LUT, which could result from enhancement of modulating descending serotonergic and noradrenergic pathways.

Predictive factors and clinical biomarkers for treatment in patients with chronic pain caused by osteoarthritis with a central sensitisation component

AIMS

The aim of this non-systematic review was to provide a practical guide for clinicians on the evidence for central sensitisation in chronic osteoarthritis (OA) pain and how this pain mechanism can be addressed in terms of clinical diagnosis, investigation and treatment.

METHODS

The authors undertook a non-systematic review of the literature including a MEDLINE search (search terms included central sensitisation, osteoarthritis, osteoarthrosis) for relevant and current clinical studies, systematic reviews and narrative reviews. Case reports, letters to the editor and similar literature sources were excluded. Information was organised to allow a pragmatic approach to the discussion of the evidence and generation of practical recommendations.

RESULTS

There is good evidence for a role of central sensitisation in chronic OA pain in a subgroup of patients. Clinically, a central sensitisation component in chronic OA pain can be suspected based on characteristic pain features and non-pain features seen in other conditions involving central sensitisation. However, there are currently no diagnostic inventories for central sensitisation specific to OA. Biomarkers may be helpful for confirming the presence of central sensitisation, especially when there is diagnostic uncertainty. Several non-pharmacological and pharmacological treatments may be effective in OA patients with central sensitisation features. Multimodal therapy may be required to achieve control of symptoms.

DISCUSSION

Clinicians should be aware of central sensitisation in patients with chronic OA pain, especially in patients presenting with severe pain with unusual features.

Effect of low intensity pulsed ultrasound on expression of TIMP-2 in serum and expression of mmp-13 in articular cartilage of rabbits with knee osteoarthritis

OBJECTIVE

To study the effect of low intensity pulsed ultrasound (LIPUS) on the expression of tissue inhibitor of metalloproteinase-2 (TIMP-2) in the serum and expression of matrix metallopeptidase 13 (MMP-13) in the articular cartilage cells of rabbits with knee osteoarthritis (OA).

METHODS

Inner patellar ligament defect method was used to establish the model of knee OA. Four weeks after the modeling, the arterial blood was drawn from the ear of each rabbit, while ELISA was employed to detect the expression of TIMP-2 in the serum. The chondrocytes were separated from animals in each group and then cultured in vitro. All rabbits were divided into control group, OA model group and OA + LIPUS group. Cells in the control and OA groups were not treated, while cells in the OA + LIPUS group were treated with LIPUS (40 mW/cm(2), 1 time/day). Cells were collected 7 d later and the RNA and total protein were extracted respectively. Real-time PCR and Western blotting were employed to analyze the expression of MMP-13 in chondrocytes at the mRNA and protein level, respectively.

RESULTS

The success rate of establishment of OA model was 83%. The results of ELISA showed that the content of TIMP-2 in the serum of animals with OA was 22.3%, lower than the one in the control group (P < 0.05). Compared with the normal control group, the expression of TIMP-2 in the OA model group was significantly increased, while the expression of MMP-13 was significantly increased (P < 0.05). After the stimulation of LIPUS, the expression of TIMP-2 and MMP-13 was close to the one in the normal control group.

CONCLUSIONS

The inner patellar ligament defect method is a mature method to establish the rabbit OA model, with high success rate. The expression of serum TIMP-2 in the OA model group is significantly decreased. LIPUS can up-regulate TIMP-2 and down-regulate MMP-13.

Anti-arthritic agents: progress and potential

Osteoarthritis and rheumatoid arthritis are the two most common types of arthritis. Cartilage breakdown is a key feature of both diseases which contributes to the pain and joint deformity experienced by patients. Therefore, anti-arthritis drugs are of great importance. The aim of this review is to present recent progress in studies of various agents against osteoarthritis and rheumatoid arthritis. The structures and activities of anti-arthritic agents, which used in medical practice or are in development, are presented and discussed. The effects and mechanisms of action of opioids, glucocorticoids, non-steroidal anti-inflammatory drugs, disease-modifying anti-rheumatic drugs, natural products derived from plants, nutraceuticals, and a number of new and perspective agents are considered. Various perspective targets for the treatment of osteoarthritis and rheumatoid arthritis are also discussed. Trials of good quality are needed to draw solid conclusions regarding efficacy of many of the studied agents. Unfortunately, to date, there is no pharmacologic agent proven to prevent the progression of both diseases, and there is an urgent need for further development of better anti-arthritic agents.

Pain management in the elderly

Persistent pain in older adults is common, and associated with substantial morbidity. Optimal management starts with assessment, including pain presence, intensity, characteristics, and interference; painful conditions; pain behaviors; pain-related morbidity; pain treatments; and coping style. Treatment incorporates analgesics demonstrated to decrease pain and improve a patient's sense of well-being. The World Health Organization's 3-step pain ladder is widely accepted and adopted for selecting analgesics among patients with non-cancer pain. Shared decision making is essential to balance the benefits and burdens of analgesics. This article reviews pain assessment/management for older adults, focusing on commonly used analgesics.

Evaluation of Duloxetine as Micronuclei Inducer in an Acute and a Subchronic Assay in Mouse

Duloxetine is a widely used antidepressant worldwide. In the present report, we evaluated its capacity to induce micronucleated polychromatic erythrocytes (MNPEs) and micronucleated normochromatic erythrocytes (MNNEs) in mice. Two assays were performed, one with a single chemical administration and the other with daily chemical administration. In the first, we administered the antidepressant once to groups of 5 mice by the intragastric (i.g.) route (2, 20, and 200 mg/kg) and performed the analysis at 24, 48, and 72 h postadministration. A control group administered i.g. distilled water was included in the assay, as well as another treated with the micronuclei-inducing chemical daunorubicin (2.5 mg/kg, injected intraperitoneally (i.p.)). In this assay, we found significant damage induced by duloxetine starting from the first time evaluated, showing the highest MNPE increase at the end of the assay. We observed a saturation effect as well, suggested by a decreasing relative efficiency with respect to each tested dose. In a second assay, we administered the antidepressant i.g. every day for 5 weeks (2, 6, and 12 mg/kg), and micronuclei analysis was performed at the end of each week. In this study, we also found a significant increase in both MNPEs and MNNEs which was clear by the second week of administration. Our results suggest that short-term as well as cumulative damage is produced by duloxetine. Thus, confirmation of the observed genotoxic potential in other models seems advisable, as well as caution when prescribing this antidepressant.

Future directions for the management of pain in osteoarthritis

Osteoarthritis (OA) is the predominant form of arthritis worldwide, resulting in a high degree of functional impairment and reduced quality of life owing to chronic pain. To date, there are no treatments that are known to modify disease progression of OA in the long term. Current treatments are largely based on the modulation of pain, including NSAIDs, opiates and, more recently, centrally acting pharmacotherapies to avert pain. This review will focus on the rationale for new avenues in pain modulation, including inhibition with anti-NGF antibodies and centrally acting analgesics. The authors also consider the potential for structure modification in cartilage/bone using growth factors and stem cell therapies. The possible mismatch between structural change and pain perception will also be discussed, introducing recent techniques that may assist in improved patient phenotyping of pain subsets in OA. Such developments could help further stratify subgroups and treatments for people with OA in future.