Opioid analgesics for rheumatoid arthritis pain

Novel trifluoromethyl ketone derivatives as oral cPLA2/COX-2 dual inhibitors for resolution of inflammation in rheumatoid arthritis

Thirty-five trifluoromethyl hydrazones and seventeen trifluoromethyl oxime esters were designed and synthesized via molecular hybridization. All the target compounds were initially screened for in vitro anti-inflammatory activity by assessing their inhibitory effect on NO release in LPS-stimulated RAW264.7 cells, and the optimal compound was finally identified as 2-(3-Methoxyphenyl)-N'-((6Z,9Z,12Z,15Z)-1,1,1-trifluorohenicosa-6,9,12,15-tetraen-2-ylidene)acetohydrazide (F26, IC50 = 4.55 ± 0.92 μM) with no cytotoxicity. Moreover, F26 potently reduced the production of PGE2 in LPS-stimulated RAW264.7 cells compared to indomethacin. The interaction of F26 with COX-2 and cPLA2 was directly verified by the CETSA technique. F26 was found to modulate the phosphorylation levels of p38 MAPK and NF-κB p65, as well as the protein expression of IκB, cPLA2, COX-2, and iNOS in LPS-stimulated rat peritoneal macrophages. Additionally, F26 was observed to prevent the nuclear translocation of NF-κB p65 in LPS-stimulated rat peritoneal macrophages by immunofluorescence localization. Therefore, the aforementioned in vitro experiments demonstrated that F26 blocked the p38 MAPK and NF-κB pathways by binding to COX-2 and cPLA2. In the adjuvant-induced arthritis model, F26 demonstrated a significant effect in preventing arthritis symptoms and inflammatory status in rats, exerting an immunomodulatory role by regulating the homeostasis between Th17 and Treg through inhibition of the p38 MAPK/cPLA2/COX-2/PGE2 and NF-κB pathways. Encouragingly, F26 caused less acute ulcerogenicity in rats at a dose of 50 mg/kg compared to indomethacin. Overall, F26 is a promising candidate worthy of further investigation for treating inflammation and associated pain with lesser gastrointestinal irritation, as well as other symptoms in which cPLA2 and COX-2 are implicated in the pathophysiology.

Discovery of novel NSAID hybrids as cPLA2/COX-2 dual inhibitors alleviating rheumatoid arthritis via inhibiting p38 MAPK pathway

A series of NSAIDs hybrid molecules were synthesized and characterized, and their ability to inhibit NO release in LPS-induced RAW264.7 macrophages was evaluated. Most of the compounds showed significant anti-inflammatory activity in vitro, of which (2E,6Z,9Z,12Z,15Z)-1,1,1-trifluorohenicosa-2,6,9,12,15-pentaen-2-yl 2-(4-benzoylphenyl) propanoate (VI-60) was the most optimal (IC50 = 3.85 ± 0.25 μΜ) and had no cytotoxicity. In addition, VI-60 notably reduced the production of PGE2 in LPS-stimulated RAW264.7 cells compared to ketoprofen. Futhur more, VI-60 significantly inhibited the expression of iNOS, cPLA2, and COX-2 and the phosphorylation of p38 MAPK in LPS-stimulated RAW264.7 cells. The binding of VI-60 to cPLA2 and COX-2 was directly verified by the CETSA technique. In vivo studies illustrated that VI-60 exerted an excellent therapeutic effect on adjuvant-induced arthritis in rats by regulating the balance between Th17 and Treg through inhibiting the p38 MAPK/cPLA2/COX-2/PGE2 pathway. Encouragingly, VI-60 showed a lower ulcerative potential in rats at a dose of 50 mg/kg compared to ketoprofen. In conclusion, the hybrid molecules of NSAIDs and trifluoromethyl enols are promising candidates worthy of further investigation for the treatment of inflammation, pain, and other symptoms in which cPLA2 and COX-2 play a role in their etiology.

How to treat chronic pain in rheumatic and musculoskeletal diseases (RMDs) - A pharmacological review

INTRODUCTION

Chronic pain is a common symptom of rheumatic diseases that impacts patients' quality of life. While non-pharmacological approaches are often recommended as first-line treatments, pharmacological interventions are important for pain management. However, the effectiveness and safety of different pharmacological treatments for chronic pain in rheumatic diseases are unclear.

METHODS

This review critically synthesizes the current evidence base to guide clinicians in selecting appropriate pharmacological treatments for their patients, considering the expected benefits and potential risks and side effects.

RESULTS

For osteoarthritis, nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, opioids, and antidepressants are commonly used, with NSAIDs being the most recommended. In addition, topical agents, such as topical NSAIDs, are recommended for localized pain relief. For fibromyalgia, amitriptyline, serotonin and noradrenaline reuptake inhibitors (SNRIs), and gabapentinoids are commonly used, with SNRIs being the most recommended. For back pain, nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, opioids are used only for acute of flare-up pain, whereas neuropathic pain drugs are only used for chronic radicular pain. For inflammatory rheumatic diseases, disease-modifying antirheumatic drugs (DMARDs) and biological agents are recommended to slow disease progression and manage symptoms.

CONCLUSION

While DMARDs and biological agents are recommended for inflammatory rheumatic diseases, pharmacological treatments for other rheumatic diseases only alleviate symptoms and do not provide a cure for the underlying condition. The use of pharmacological treatments should be based on the expected benefits and evaluation of side effects, with non-pharmacological modalities also being considered, especially for fibromyalgia.

Anti-inflammatory and analgesic effect of Forsythiaside B on complete Freund's adjuvant-induced inflammatory pain in mice

Chronic pain is frequently reported in clinical practice. Therefore, it is important to identify effective therapy to relieve pain. In this work, we selected Forsythoside B (FB), a phenylethanoid glycoside isolated from Forsythia suspensa (Thunb.) Vahl, to evaluate its effect in modulating inflammatory pain induced by complete Freund's adjuvant (CFA) and the involved mechanisms. We discovered that FB could attenuate inflammatory pain triggered by CFA injection and exert anti-anxiety effects. In detail, proinflammatory cytokines, consisting of IL-6 and TNF-α, were decreased after FB administration in the CFA-injected mice. Furthermore, the FB application ameliorated the activation of ionized calcium-binding adaptor molecule 1 (Iba-1) and glial fibrillary acidic protein (GFAP), the microglia and astrocytes markers respectively. Therefore, our findings indicate that FB could be a promising treatment for chronic inflammatory pain.

Review of publications evaluating opioid use in patients with inflammatory rheumatic disease

PURPOSE OF REVIEW

This article discusses publications assessing the prevalence, efficacy, and safety of opioid analgesics in patients with rheumatic diseases, including rheumatoid arthritis, systemic lupus erythematosus, psoriatic arthritis, ankylosing spondylitis, and systemic sclerosis.

RECENT FINDINGS

Recent studies show long-term opioid use is common in patients with inflammatory rheumatic disease. We did not find any studies demonstrating improved function or pain control with long-term opioid use in people with rheumatic diseases. Some data shows potential adverse effects including increased risk for fractures and opioid poisoning hospitalizations. There is evidence demonstrating an association of opioid use with mental health disorders, fibromyalgia, obesity, and disability, although causative links have not been established. Only minimal reductions in opioid use were observed after initiation of biologic disease modifying antirheumatic drugs (DMARDs). Studies have shown delayed DMARD initiation and reduced DMARD use in patients on opioids, raising concerns that these analgesics may delay care or initially mask symptoms of active disease.

SUMMARY

Available literature highlights high levels of opioid use in people with rheumatic disease, without scientific evidence to support efficacy for chronic pain control and increasing evidence of adverse events. These findings strongly suggest that opioids do not have a routine role in the chronic management of inflammatory rheumatic diseases.

Recent advances in the opioid mu receptor based pharmacotherapy for rheumatoid arthritis

INTRODUCTION

Opioids are used for severe forms of acute and cancer pain. Over the last years, their potential use in patients with noncancer pain such as those with rheumatoid arthritis (RA) has been postulated. A recent population-based comparative study showed that chronic opioid use was 12% vs. 4% among RA and non-RA patients, respectively. Another study showed an increase from 7.4% to 16.9% (2002 to 2015). In general, there has been an increasing tendency to use opioids in recent years.

AREAS COVERED

The authors have performed an extensive literature search using PubMed for articles including noncancer pain and the use of the mu opioid receptor (MOR) agonists in patients with RA.

EXPERT OPINION

Data is not sufficient to support opioid use for the treatment of chronic pain in patients with RA. Data is scarce and inconclusive. Rheumatologists should think and ponder the question: Why is this patient in pain? Differential diagnosis should include a disease flare, degenerative changes of the musculoskeletal system, and fibromyalgia. And while there are new strategies for opioid administration currently being researched, unfortunately, they are far from being applied to human subjects in the everyday clinical setting, and are still being evaluated at an experimental level. CNS: Central nervous system; DORs: delta opioid receptor agonists; GI: Gastrointestinal; GPCRs: G protein-coupled receptors; IL: Interleukin; JAK: Janus kinase; KORs: kappa opioid receptor agonists; MCPs: Metacarpophalangeal joints; MORs: Mu opioid receptor agonists; MTPs: Metatarsophalangeal joints; NSAIDs: Non-steroidal anti-inflammatory drugsOA: Osteoarthritis; ORs: Opioid receptors; PD: Pharmacodynamic; PIPs: Proximal interphalangeal joints; PK: Pharmacokinetic; PNS: Peripheral nervous system; RA: Rheumatoid arthritis; RGS: Regulator of G protein signaling; SSRIs: Selective serotonin reuptake inhibitors; TNF: Tumor necrosis factor.

Dorsal Root Ganglion Stimulation Alleviates Pain-related Behaviors in Rats with Nerve Injury and Osteoarthritis

BACKGROUND

Dorsal root ganglion field stimulation is an analgesic neuromodulation approach in use clinically, but its mechanism is unknown as there is no validated animal model for this purpose. The authors hypothesized that ganglion stimulation is effective in reducing pain-like behaviors in preclinical chronic pain models.

METHODS

The authors provided ganglion stimulation or spinal cord stimulation to rats with traumatic neuropathy (tibial nerve injury), or osteoarthritis induced by intraarticular knee monosodium iodoacetate, or without injury (naïve). Analgesia was evaluated by testing a battery of pain-related reflexive, functional, and affective behaviors.

RESULTS

In rats with nerve injury, multilevel L4 and L5 ganglion stimulation decreased hypersensitivity to noxious mechanical stimulation more (area under curve, -1,447 ± 423 min × % response; n = 12) than single level ganglion stimulation at L4 ([-960 ± 251 min × % response; n = 8; P = 0.012] vs. L4 and L5), and L5 ([-676 ± 295 min × % response; n = 8; P < 0.0001] vs. L4 and L5). Spontaneous pain-like behavior, evaluated by conditioned place preference, responded to single L4 (Pretest [-93 ± 65 s] vs. Test [87 ± 82 s]; P = 0.002; n = 9), L5 (Pretest [-57 ± 36 s] vs. Test [137 ± 73 s]; P = 0.001; n = 8), and multilevel L4 and L5 (Pretest: -81 ± 68 s vs. Test: 90 ± 76 s; P = 0.003; n = 8) ganglion stimulation. In rats with osteoarthritis, multilevel L3 and L4 ganglion stimulation reduced sensitivity to knee motion more (-156 ± 28 min × points; n = 8) than L3 ([-94 ± 19 min × points in knee bend test; n = 7; P = 0.002] vs. L3 and L4) or L4 ([-71 ± 22 min × points; n = 7; P < 0.0001] vs. L3 and L4). Conditioned place preference during osteoarthritis revealed analgesic effectiveness for ganglion stimulation when delivered at L3 (Pretest [-78 ± 77 s] vs. Test [68 ± 136 s]; P = 0.048; n = 9), L4 (Pretest [-96 ± 51 s] vs. Test [73 ± 111 s]; P = 0.004; n = 9), and L3 and L4 (Pretest [-69 ± 52 s; n = 7] vs. Test [55 ± 140 s]; P = 0.022; n = 7).

CONCLUSIONS

Dorsal root ganglion stimulation is effective in neuropathic and osteoarthritic preclinical rat pain models with peripheral pathologic origins, demonstrating effectiveness of ganglion stimulation in a placebo-free setting and justifying this model as a suitable platform for mechanistic studies.

Opioid Use among Patients with Early Inflammatory Arthritides Compared to the General Population

OBJECTIVE

To assess to what extent the worldwide opioid epidemic affects Finnish patients with early inflammatory arthritis (IA).

METHODS

From the nationwide register maintained by the Social Insurance Institution of Finland, we collected all incident adult patients with newly onset seropositive and seronegative rheumatoid arthritis (RA+ and RA-) and undifferentiated arthritis (UA) between 2010 and 2014. For each case, 3 general population (GP) controls were matched according to age, sex, and place of residence. Drug purchases between 2009 and 2015 were evaluated 1 year before and after the index date (date of IA diagnosis), further dividing this time into 3-month periods.

RESULTS

A total of 12,115 patients (66% women) were identified. At least 1 opioid purchase was done by 23-27% of the patients 1 year before and 15-20% one year after the index date. Relative risk (RR) of opioid purchases compared to GP was highest during the last 3-month time period before the index date [RR 2.81 (95% CI 2.55-3.09), 3.06 (2.68-3.49), and 4.04 (3.51-4.65) for RA+, RA-, and UA, respectively] but decreased after the index date [RR 1.38 (1.23-1.58), 1.91 (1.63-2.24), and 2.51 (2.15-2.93)]. Up to 4% of the patients were longterm users both before and after the diagnosis.

CONCLUSION

During 2009-15 in Finland, opioid use peaked just before the diagnosis of IA but decreased rapidly after that, suggesting effective disease control, especially in seropositive RA. Further, opioids were used to treat arthritis pain of patients with incident RA and UA less often than previously reported from other countries.

Changes in Opioid Utilization Following Tumor Necrosis Factor Inhibitor Initiation in Patients with Rheumatoid Arthritis

INTRODUCTION

Pain control is one of the most important aspects of rheumatoid arthritis (RA) management from the patient's perspective. Newer generations of RA treatment including tumor necrosis factor inhibitor (TNFi) have the potential to alleviate pain and thus reduce opioid utilization. However, patterns of opioid utilization before and after TNFi initiation have not been well characterized. This study aims to examine multiple measures of change in opioid utilization after the initiation of TNFi.

METHODS

Patients aged ≥ 18 years with RA and 24 months continuous enrollment between January 2007 and December 2015 who newly initiated a TNFi in IQVIA™ Health Plan Claims Data were included in our study. Opioid utilization at baseline and during follow-up were identified and compared.

RESULTS

Of 2330 patients with RA that were included in the study, 38.8% of patients used opioids in both baseline and follow-up periods. From pre-index to post-index, the proportion of patients receiving any opioid decreased from 54.0 to 51.0%. In addition, the proportion of those who received ≥ 50 mg median daily MED decreased from 12.6 to 10.6% during pre-post periods.

CONCLUSIONS

This real-world study of commercially insured patients with RA suggests that opioid use among these patients is prevalent. There was a small decrease in overall opioid utilization after TNFi initiation.

Chronic Opioid Use in Rheumatoid Arthritis: Prevalence and Predictors

OBJECTIVE

The opioid epidemic is a major public health concern. However, little is known about opioid use among rheumatoid arthritis (RA) patients. We undertook this study to examine trends in chronic opioid use in RA patients in 2002-2015 and to identify clinical predictors.

METHODS

RA patients were identified from the Corrona registry. Opioid use was ascertained from surveys obtained at clinical visits as often as every 3 months. Chronic opioid use was defined as any opioid use reported during ≥2 consecutive study visits. Annual prevalence of chronic opioid use was calculated using data from 33,739 RA patients with information on opioid use from ≥2 visits. Among the 26,288 individuals who were not taking opioids at baseline, Cox proportional hazards models identified associations between patient characteristics and incident chronic opioid use. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Chronic opioid use increased from 7.4% in 2002 to 16.9% in 2015. Severe pain (HR 2.53 [95% CI 2.19-2.92]) and antidepressant use (HR 1.79 [95% CI 1.64-1.92]) were associated with an increased risk of chronic opioid use. High disease activity (HR 1.55 [95% CI 1.30-1.84]) and a high level of disability (HR 1.45 [95% CI 1.27-1.65]) were also associated with chronic opioid use, whereas Asian ethnicity (HR 0.49 [95% CI 0.36-0.68]) was associated with a decreased risk of chronic opioid use.

CONCLUSION

Among RA patients, chronic opioid use doubled from 2002 to 2015. Pain and antidepressant use were the strongest predictors of chronic opioid use. To curb the rise in chronic opioid use, strategies for stringent control of RA disease activity and management of pain and depression should be research priorities.

Evaluation of opioid use among patients with back disorders and arthritis

PURPOSE

Long-term opioid use for chronic pain has increased, but limited evidence exists on its benefits. Evaluation of long-term benefits in pain is based on patient-reported measures such as health-related quality of life (HRQoL). This study examined the long-term effects of opioid use on HRQoL and its subdomains in patients with back pain or arthritis by comparing opioid users to non-opioid users for three metrics: (1) any opioid use, (2) duration of opioid use, and (3) average daily morphine equivalent dose.

METHODS

A nationally representative sample of cancer-free adults with chronic back pain or arthritis was selected. Using the 12-Item Short Form Survey, HRQoL measures of Mental Component Score (MCS), Physical Component Score (PCS), and individual subdomains were assessed at baseline and 1 year later. Opioid users were matched to non-opioid users in a 1:1 greedy match using propensity scores estimated based on many patient demographics and baseline HRQoL measures.

RESULTS

At year one, PCS was significantly lower among opioid users, mostly driven by bodily pain subdomain; MCS was not different. Short-term opioid users (< 1 month) had higher MCS while long-term users (≥ 1 month) had lower PCS. Low-dose [< 20 morphine milligram equivalents (MME)/day] opioid use was associated with lower PCS, while no difference was found between high dose (≥ 20 MME/day) and non-opioid users. However, most differences were not clinically significant.

CONCLUSIONS

Long-term opioid use is not associated with improvements in HRQoL. Clinicians should carefully evaluate the need for opioid use, especially long-term use in managing chronic back pain and arthritis.

Topical Loperamide-Encapsulated Liposomal Gel Increases the Severity of Inflammation and Accelerates Disease Progression in the Adjuvant-Induced Model of Experimental Rheumatoid Arthritis

This study evaluates the prophylactic effect of the peripherally-selective mu-opioid receptor agonist, loperamide, administered topically in a liposomal gel formulation on pain, inflammation, and disease progression in the adjuvant-induced model of experimental rheumatoid arthritis in female Lewis rats. In a randomized, blinded and controlled animal trial, AIA rats were divided into six groups consisting of eleven rats per group based on the following treatments: loperamide liposomal gel, free loperamide gel, empty liposomal gel, diclofenac gel (Voltaren®), no treatment, and naive control. Topical formulations were applied daily for a maximum of 17 days-starting from day 0 at the same time as immunization. The time course of the effect of the treatments on antinocieption and inflammation was assessed using a paw pressure analgesiometer and plethysmometer, respectively. Arthritis progression was scored daily using an established scoring protocol. At the end of the study, hind paws were processed for histological analysis. Administration of loperamide liposomal gel daily across the duration of the study produced significant peripheral antinociception as expected; however, increased the severity of inflammation and accelerated arthritis progression. This was indicated by an increase in paw volume, behavioral and observational scoring, and histological analysis compared to the control groups. In particular, histology results showed an increase in pannus formation and synovial inflammation, as well as an upregulation of markers of inflammation and angiogenesis. These findings may have implications for the use of loperamide and other opioids in arthritis and potentially other chronic inflammatory diseases.

Effects of Koumine on Adjuvant- and Collagen-Induced Arthritis in Rats

To examine the effect of koumine, a Gelsemium alkaloid, on two experimental models of rheumatoid arthritis (RA), rats with adjuvant-induced arthritis (AIA) and collagen-induced arthritis (CIA) were administered koumine (0.6, 3, or 15 mg/kg/day) or vehicle through gastric gavage (i.g.). Clinical evaluation was performed via measurements of hind paw volume, arthritis index (AI) score, mechanical withdrawal threshold, organ weight, and by radiographic and histological examinations. Levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and antitype II collagen (CII) antibody were also examined. In rats with AIA, koumine reduced the AI score and mechanical allodynia of the injected hind paw in a dose-dependent manner and significantly inhibited increase in thymus and liver weights. In rats with CIA, koumine inhibited increase in hind paw volume, AI score, and mechanical allodynia in a dose-dependent manner and reduced joint space narrowing. Furthermore, koumine also attenuated the increase in the expression of IL-1β and TNF-α, as well as the robust increase of serum anti-CII antibodies in response to immunization. These results suggested that koumine effectively attenuated arthritis progression in two rat models of RA and that this therapeutic effect may be associated with its immunoregulatory action.

Pain management in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the most common inflammatory conditions in the United States affecting approximately 1 million adults. This article briefly reviews the evidence-based diagnosis of RA, mainstays of treatment to prevent joint destruction, and pain management.

Uncovering pharmacological mechanisms of Wu-tou decoction acting on rheumatoid arthritis through systems approaches: drug-target prediction, network analysis and experimental validation

Wu-tou decoction (WTD) has been extensively used for the treatment of rheumatoid arthritis (RA). Due to lack of appropriate methods, pharmacological mechanisms of WTD acting on RA have not been fully elucidated. In this study, a list of putative targets for compositive compounds containing in WTD were predicted by drugCIPHER-CS. Then, the interaction network of the putative targets of WTD and known RA-related targets was constructed and hub nodes were identified. After constructing the interaction network of hubs, four topological features of each hub, including degree, node betweenness, closeness and k-coreness, were calculated and 79 major hubs were identified as candidate targets of WTD, which were implicated into the imbalance of the nervous, endocrine and immune (NEI) systems, leading to the main pathological changes during the RA progression. Further experimental validation also demonstrated the preventive effects of WTD on inflammation and joint destruction in collagen-induced arthritis (CIA) rats and its regulatory effects on candidate targets both in vitro and in vivo systems. In conclusion, we performed an integrative analysis to offer the convincing evidence that WTD may attenuate RA partially by restoring the balance of NEI system and subsequently reversing the pathological events during RA progression.

S1RA, a selective sigma-1 receptor antagonist, inhibits inflammatory pain in the carrageenan and complete Freund's adjuvant models in mice

The therapeutic potential of S1RA (E-52862), a selective sigma-1 receptor (σ1R) antagonist, has been explored in experimental neuropathic pain, but not in inflammatory pain models. The present study investigated the effect of the intraperitoneal administration of S1RA on the hind paw withdrawal response to thermal and mechanical stimulation following an intraplantar injection of carrageenan (CARR) and complete Freund's adjuvant (CFA), which are two well-characterized models of acute and chronic inflammatory pain, respectively. S1RA fully reversed both mechanical [dose of drug that produced half of its maximal response (ED50)=35.9 and 42.1 mg/kg for CARR-induced and CFA-induced pain, respectively] and thermal (ED50=27.9 mg/kg, CARR) hypersensitivity, whereas ibuprofen (CARR, mechanical allodynia) and celecoxib (CARR, thermal hyperalgesia; CFA, mechanical allodynia) failed to reach maximum efficacy. Morphine also showed maximum efficacy in all tests. Unlike celecoxib and ibuprofen, which decreased paw volume significantly, CARR-induced paw oedema was not reduced by S1RA and morphine, thus suggesting that the antinociceptive effect of S1RA does not involve a major anti-inflammatory (antioedema) action. S1RA was devoid of efficacy when administered to σ1R knockout mice, thus suggesting the involvement of σ1R in the antinociceptive effects exerted by S1RA. We conclude that S1RA represents a promising novel analgesic therapy for inflammatory pain.