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.

Pharmacological treatments of fibromyalgia in adults; overview of phase IV clinical trials

Background: Fibromyalgia is a chronic neurological condition characterized by widespread pain. The effectiveness of current pharmacological treatments is limited. However, several medications have been approved for phase IV trials in order to evaluate them.

Aim: To identify and provide details of drugs that have been tested in completed phase IV clinical trials for fibromyalgia management in adults, including the primary endpoints and treatment outcomes. This article was submitted to Neuropharmacology, a section of the journal Frontiers in Pharmacology.

Method: Publicly available and relevant phase IV trials registered at ClinicalTrials.gov were analyzed. The uses of the trialed drugs for fibromyalgia were reviewed.

Results: As of 8 August 2022, a total of 1,263 phase IV clinical trials were identified, of which 121 were related to fibromyalgia. From these, 10 clinical trials met the inclusion criteria for the current study. The drugs used in phase IV trials are milnacipran, duloxetine, pregabalin, a combination of tramadol and acetaminophen, and armodafinil. The effectiveness of the current pharmacological treatments is apparently limited.

Conclusion: Due to its complexity and association with other functional pain syndromes, treatment options for fibromyalgia only are limited and they are designed to alleviate the symptoms rather than to alter the pathological pathway of the condition itself. Pain management specialists have numerous pharmacologic options available for the management of fibromyalgia.

Fibromyalgia: Recent Advances in Diagnosis, Classification, Pharmacotherapy and Alternative Remedies

Fibromyalgia (FM) is a syndrome that does not present a well-defined underlying organic disease. FM is a condition which has been associated with diseases such as infections, diabetes, psychiatric or neurological disorders, rheumatic pathologies, and is a disorder that rather than diagnosis of exclusion requires positive diagnosis. A multidimensional approach is required for the management of FM, including pain management, pharmacological therapies, behavioral therapy, patient education, and exercise. The purpose of this review is to summarize the recent advances in classification criteria and diagnostic criteria for FM as well as to explore pharmacotherapy and the use of alternative therapies including the use of plant bioactive molecules.

Association between erectile dysfunction and fibromyalgia in male patients: A Taiwanese nationwide population-based cohort study

OBJECTIVES

To investigate the association between erectile dysfunction and fibromyalgia, and to clarify related comorbidities and treatment modalities.

METHODS

This retrospective cohort study was carried out using 1 million records in the National Health Insurance Research Database. From 2001 to 2012, a total of 53 678 male patients newly diagnosed with fibromyalgia were recruited as the fibromyalgia cohort, and the same number of the non-fibromyalgia cohort was enrolled and matched with propensity score with age, income, comorbidities, and prescribed medications. All records were followed up until the end of 2013. The Cox proportional hazards model was carried out to assess the risk of erectile dysfunction among fibromyalgia patients.

RESULTS

The incidence rates of erectile dysfunction were 36.86 and 21.15 (per 10 000 person-years) in the fibromyalgia and non-fibromyalgia cohorts, respectively, and a significantly increased risk of erectile dysfunction in fibromyalgia patients was noted (adjusted hazard ratio 1.69, 95% confidence interval 1.55-1.85, P < 0.001). The Cox proportional hazards regression analysis showed increased risk of erectile dysfunction in the fibromyalgia cohort regardless of treatment prescriptions of tramadol, antidepressants, gabapentin and non-steroidal anti-inflammatory drugs.

CONCLUSIONS

Fibromyalgia was found to be an independent risk factor for the incidence of erectile dysfunction.

Tramadol for management of fibromyalgia pain and symptoms: Systematic review

BACKGROUND

Fibromyalgia is a heterogeneous condition that appears to be associated with physiological and biochemical disturbances of pain modulation, and that consequently affects numerous other facets of life. Tramadol is currently being explored as an option to manage fibromyalgia pain and other symptoms because of its inhibitory activity of reuptake of neurotransmitters, but its safety and efficacy have not yet been established in these patients.

OBJECTIVE

To evaluate the effectiveness and safety of tramadol on the management of symptoms of the syndrome.

METHODS

We searched CENTRAL, MEDLINE, EMBASE, LILACS, Opengrey, ClinicalTrials.gov and WHO-ICTRP for randomised controlled trials analysing the association between tramadol used for fibromyalgia either single-agent or in combination with other drugs. Two reviewers independently extracted data and assessed risk of bias using the Cochrane risk-of-bias tool for all included studies. Quality of the evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

Four RCTs comprising 459 patients were included. Tramadol-either as a single-agent or in combination with an antidepressant or analgesic-had a positive effect on pain. Tramadol combined with analgesic showed improved quality of life over placebo as measured by the Fibromyalgia Impact Questionnaire at 91 days. However, this difference did not hold for tramadol as a single agent against placebo. The evidence in these articles was rated "low" using the GRADE approach. No serious adverse events were reported. No improvement in depression and quality of sleep were observed.

CONCLUSIONS

This systematic review found a dearth of clinical trials on tramadol in patients with fibromyalgia. Although the combination of monoamine and opioid mechanism of tramadol has shown positive effects for fibromyalgia, the available evidence is not sufficient to support or refute the use of tramadol in clinical practice for pain or symptom management. Protocol registration number in the PROSPERO database: CRD42017062139.

Medical Cannabis for the Treatment of Fibromyalgia

BACKGROUND

Fibromyalgia is a chronic pain syndrome, characterized by chronic musculoskeletal pain, fatigue, and mood disturbances. There are nearly no data on the effect of medical cannabis (MC) treatment on patients with fibromyalgia.

METHODS

Data were obtained from the registries of 2 hospitals in Israel (Laniado Hospital and Nazareth Hospital) on patients with a diagnosis of fibromyalgia who were treated with MC. After obtaining patient consent, demographic, clinical, and laboratory parameters were documented. All the patients also completed the Revised Fibromyalgia Impact Questionnaire regarding the period before and after MC treatment.

RESULTS

Thirty patients were identified, and 26 patients were included in the study. There were 19 female patients (73%), and the mean age of the study group was 37.8 ± 7.6 years. The mean dosage of MC was 26 ± 8.3 g per month, and the mean duration of MC use was 10.4 ± 11.3 months. After commencing MC treatment, all the patients reported a significant improvement in every parameter on the questionnaire, and 13 patients (50%) stopped taking any other medications for fibromyalgia. Eight patients (30%) experienced very mild adverse effects.

CONCLUSIONS

Medical cannabis treatment had a significant favorable effect on patients with fibromyalgia, with few adverse effects.

Docking, characterization and investigation of β-cyclodextrin complexed with citronellal, a monoterpene present in the essential oil of Cymbopogon species, as an anti-hyperalgesic agent in chronic muscle pain model

BACKGROUND

Citronellal (CT) is a monoterpene with antinociceptive acute effect. β-Cyclodextrin (βCD) has enhanced the analgesic effect of various substances.

HYPOTHESIS/PURPOSE

To evaluate the effect of CT both complexed in β-cyclodextrin (CT-βCD) and non-complexed, in a chronic muscle pain model (CMP) in mice.

STUDY DESIGN

The complex containing CT in βCD was obtained and characterized in the laboratory. The anti-hyperalgesic effect of CT and CT-βCD was evaluated in a pre-clinical in vivo study in a murine CMP.

METHODS

The complex was characterized through differential scanning calorimetry, derivative thermogravimetry, moisture determination, infrared spectroscopy and scanning electron microscopy. Male Swiss mice were pre-treated with CT (50mg/kg, po), CT-βCD (50mg/kg, po), vehicle (isotonic saline, po) or standard drug (tramadol4 mg/kg, ip). 60 min after the treatment and then each 1h, the mechanic hyperalgesia was evaluated to obtain the time effect. In addition, the muscle strength using grip strength meter and hyperalgesia were also performed daily, for 7 days. We assessed by immunofluorescence for Fos protein on brains and spinal cords of mice. The involvement of the CT with the glutamatergic system was studied with molecular docking.

RESULTS

All characterization methods showed the CT-βCD complexation. CT-induced anti-hyperalgesic effect lasted until 6h (p <0.001) while CT-βCD lasted until 8h (p <0.001vs vehicle and p <0.001vs CT from the 6th h). CT-βCD reduced mechanical hyperalgesia on all days of treatment (p <0.05), without changing muscle strength. Periaqueductal gray (p <0.01) and rostroventromedular area (p <0.05) showed significant increase in the Fos protein expression while in the spinal cord, there was a reduction (p <0.001). CT showed favorable energy binding (-5.6 and -6.1) to GluR2-S1S2J protein based in the docking score function.

CONCLUSION

We can suggest that βCD improved the anti-hyperalgesic effect of CT, and that effect seems to involve the descending pain-inhibitory mechanisms, with a possible interaction of the glutamate receptors, which are considered as promising molecules for the management of chronic pain such as CMP.

Is there a role for opioids in the treatment of fibromyalgia?

The use of opioids for chronic pain has increased significantly due to a combination of the high patient burden of pain and the more widespread availability of a range of long-acting opioid preparations. This increased opioid use has translated into the care of many patients with fibromyalgia. The pain mechanism in fibromyalgia is complex but does not seem to involve disturbance of opioid analgesic functions. Hence, there is general concern about the harms in the absence of benefits of opioids in this setting. There is no evidence that pure opioids are effective in fibromyalgia but there is some evidence that opioids with additional actions on the norepinephrine-related pain modulatory pathways, such as tramadol, can be clinically useful in some patients. Novel actions of low-dose opioid antagonists may lead to better understanding of the role of opioid function in fibromyalgia.