Pregabalin for the treatment of fibromyalgia syndrome: Results of a randomized, double-blind, placebo-controlled trial

Pharmacological Treatment of Fibromyalgia Syndrome: A Practice-Based Review

PURPOSE OF REVIEW

Fibromyalgia Syndrome (FMS) is a complex chronic pain condition characterized by widespread musculoskeletal pain and numerous other debilitating symptoms. The purpose of this review is to provide a comprehensive overview, based on everyday clinical practice, of the drugs presently employed in the treatment of FMS.

RECENT FINDINGS

The treatment of FMS is based on a multimodal approach, with pharmacologic treatment being an essential pillar. The drugs used include tricyclic antidepressants, serotonin and noradrenaline reuptake inhibitors, other antidepressants, anticonvulsants, myorelaxants, and analgesics. The effectiveness of these medications varies, and the choice of drug often depends on the specific symptoms presented by the patient. Many drugs tend to either address only some domains of the complex FMS symptomatology or have a limited effect on pain. Each treatment option comes with potential side effects and risks that necessitate careful consideration. It may be beneficial to divide patients into clinical subpopulations, such as FMS with comorbid depression, for more effective treatment. Despite the complexities and challenges, the pharmacological treatment remains a crucial part for the management of FMS. This review aims to guide clinicians in prescribing pharmacological treatment to individuals with FMS.

Pregabalin produces analgesia in males but not females in an animal model of chronic widespread muscle pain

Introduction

Pregabalin, which acts on the α2δ-1 subunit of voltage-gated calcium channels, relieves ≥50% of pain in a third of individuals with fibromyalgia. Thus far, preclinical studies of pregabalin have predominantly used male animals.

Objectives

The purpose of our study was to investigate potential sex differences in the analgesic efficacy of pregabalin that may contribute to disparities in human outcomes.

Methods

We used a mouse model of chronic widespread muscle pain (CWP) to test the effects of pregabalin on muscle hyperalgesia, nonreflexive pain, and motor behaviors. The CWP pain model combines 2 pH 4.0 saline injections, spaced 5 days apart, into the gastrocnemius muscle and produces bilateral muscle hyperalgesia. Furthermore, we explored sex differences in the mRNA and protein expression of the α2δ-1 subunit of voltage-gated calcium channels in the dorsal horn of the spinal cord and dorsal root ganglia after development of CWP.

Results

Pregabalin fully attenuated muscle hyperalgesia bilaterally in male but not female mice with equal motor deficits produced in both sexes. In addition, using the conditioned place preference test, mice of both sexes with CWP spent significantly more time in the pregabalin-paired chamber compared with baseline, but not significantly greater than pain-free controls. Chronic widespread muscle pain produced no changes in α2δ-1 subunit mRNA or protein expression in the dorsal horn of the spinal cord or dorsal root ganglia in either sex.

Conclusion

Overall, these findings indicate pregabalin may be more effective in treating CWP in males, but the factors leading to these differences are not fully understood.

Pharmacotherapeutic advances in fibromyalgia: what's new on the horizon?

INTRODUCTION

This review delves into Fibromyalgia Syndrome (FMS), a chronic pain condition demanding thorough understanding for precise diagnosis and treatment. Yet, a definitive pharmacological solution for FMS remains elusive.

AREAS COVERED

In this article, we systematically analyze various pharmacotherapeutic prospects for FMS treatment, organized into sections based on the stage of drug development and approval. We begin with an overview of FDA-approved drugs, discussing their efficacy in FMS treatment. Next, we delve into other medications currently used for FMS but still undergoing further study, including opioids and muscle relaxants. Further, we evaluate the evidence behind medications that are currently under study, such as cannabinoids and naltrexone. Lastly, we explore new drugs that are in phase II trials. Our research involved a thorough search on PUBMED, Google Scholar, and clinicaltrials.gov. We also discuss the action mechanisms of these drugs and their potential use in specific patient groups.

EXPERT OPINION

A focus on symptom-driven, combination therapy is crucial in managing FMS. There is also a need for ongoing research into drugs that target neuroinflammation, immunomodulation, and the endocannabinoid system. Bridging the gap between benchside research and clinical application is challenging, but it holds potential for more targeted and effective treatment strategies.

"Fibromyalgia - are there any new approaches?"

INTRODUCTION

Approaching patients with fibromyalgia (FM) is challenging due to the limited availability of scientifically proven effective therapies.

OBJECTIVE

Review the treatments in use for FM and present new knowledge that could benefit these patients. Non-pharmacological interventions are recommended as the first line of treatment: aerobic exercise, cognitive behavioral therapy and patient education, all aimed at improving pain and other symptoms. Additional approaches have been studied, such as, digital health interventions, combined treatments, noninvasive neuromodulation, and others. Concerning pharmacological therapy, the mechanism of action of the medications currently used is to promote pain modulation. Medications approved by Food and Drug Administration are duloxetine, milnacipran and pregabalin. Amitriptyline, cyclobenzaprine, gabapentin and naltrexone are considered for off-label use. Cannabinoids, vitamin D supplementation are still controversial and further research is needed.

CONCLUSION

The combination of therapies, whether old, recent or reformulated, are the most effective strategy for managing symptoms in patients with fibromyalgia.

KEY WORDS

fibromyalgia, treatment, nonpharmacological interventions, pharmacological treatment.

Exploring the Relationship between Diamine Oxidase and Psychotropic Medications in Fibromyalgia Treatment, Finding No Reduction in Diamine Oxidase Levels and Activity except with Citalopram

Background: Histamine intolerance manifests when there is an imbalance between the production of histamine and the body's capacity to metabolise it. Within the gastrointestinal tract, diamine oxidase (DAO) plays a pivotal role in breaking down ingested histamine. Insufficient levels of DAO have been linked to various diseases affecting the respiratory, cardiovascular, nervous, muscular, and digestive systems; some of these symptoms are evidenced in fibromyalgia syndrome. This underscores the crucial role of DAO in maintaining the histamine balance and highlights its association with diverse physiological systems and health conditions. The management of fibromyalgia commonly involves the use of psychotropic medications; however, their potential interactions with DAO remain not fully elucidated. Methods: This study delved into the influence of various psychotropic medications on DAO activity through in vitro experiments. Additionally, we explored their impact on the human intestinal cell line Caco-2, examining alterations in DAO expression at both the mRNA and protein levels along with DAO activity. Results: Notably, the examined drugs-sertraline, pregabalin, paroxetine, alprazolam, and lorazepam-did not exhibit inhibitory effects on DAO activity or lead to reductions in DAO levels. In contrast, citalopram demonstrated a decrease in DAO activity in in vitro assays without influencing DAO levels and activity in human enterocytes. Conclusions: These findings imply that a collaborative approach involving psychotropic medications and DAO enzyme supplementation for individuals with fibromyalgia and a DAO deficiency could offer potential benefits for healthcare professionals in their routine clinical practice.

Dry eye symptoms and signs in United States Gulf War era veterans with myalgic encephalomyelitis/chronic fatigue syndrome

BACKGROUND

To examine ocular symptoms and signs of veterans with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) diagnosis, ME/CFS symptoms, and controls.

METHODS

This was a prospective, cross-sectional study of 124 South Florida veterans in active duty during the Gulf War era. Participants were recruited at an ophthalmology clinic at the Miami Veterans Affairs Hospital and evaluated for a diagnosis of ME/CFS, or symptoms of ME/CFS (intermediate fatigue, IF) using the Canadian Consensus criteria. Ocular symptoms were assessed via standardised questionnaires and signs via comprehensive slit lamp examination. Inflammatory blood markers were analysed and compared across groups.

RESULTS

Mean age was 55.1 ± 4.7 years, 88.7% identified as male, 58.1% as White, and 39.5% as Hispanic. Ocular symptoms were more severe in the ME/CFS (n = 32) and IF (n = 48) groups compared to controls (n = 44) across dry eye (DE; Ocular Surface Disease Index [OSDI]: 48.9 ± 22.3 vs. 38.8 ± 23.3 vs. 19.1 ± 17.8, p < 0.001; 5 item Dry Eye Questionnaire [DEQ-5]: 10.8 ± 3.9 vs. 10.0 ± 4.6 vs. 6.6 ± 4.2, p < 0.001) and pain-specific questionnaires (Numerical Rating Scale 1-10 [NRS] right now: 2.4 ± 2.8 vs. 2.4 ± 2.9 vs 0.9 ± 1.5; p = 0.007; Neuropathic Pain Symptom Inventory modified for the Eye [NPSI-E]: 23.0 ± 18.6 vs. 19.8 ± 19.1 vs. 6.5 ± 9.0, p < 0.001). Ocular surface parameters and blood markers of inflammation were generally similar across groups.

CONCLUSION

Individuals with ME/CFS report increased ocular pain but similar DE signs, suggesting that mechanisms beyond the ocular surface contribute to symptoms.

Fibromyalgia Animal Models Using Intermittent Cold and Psychological Stress

Fibromyalgia (FM) is a chronic pain condition characterized by widespread musculoskeletal pain and other frequent symptoms such as fatigue, sleep disturbance, cognitive impairment, and mood disorder. Based on the view that intermittent stress would be the most probable etiology for FM, intermittent cold- and intermittent psychological stress-induced generalized pain (ICGP and IPGP) models in mice have been developed and validated as FM-like pain models in terms of the patho-physiological and pharmacotherapeutic features that are shared with clinical versions. Both models show long-lasting and generalized pain and female-predominant sex differences after gonadectomy. Like many other neuropathic pain models, ICGP and IPGP were abolished in lysophosphatidic acid receptor 1 (LPAR1) knock-out mice or by LPAR1 antagonist treatments, although deciding the clinical importance of this mechanism depends on waiting for the development of a clinically available LPAR1 antagonist. On the other hand, the nonsteroidal anti-inflammatory drug diclofenac with morphine did not suppress hyperalgesia in these models, and this is consistent with the clinical findings. Pharmacological studies suggest that the lack of morphine analgesia is associated with opioid tolerance upon the stress-induced release of endorphins and subsequent counterbalance through anti-opioid NMDA receptor mechanisms. Regarding pharmacotherapy, hyperalgesia in both models was suppressed by pregabalin and duloxetine, which have been approved for FM treatment in clinic. Notably, repeated treatments with mirtazapine, an α2 adrenergic receptor antagonist-type antidepressant, and donepezil, a drug for treating Alzheimer's disease, showed potent therapeutic actions in these models. However, the pharmacotherapeutic treatment should be carried out 3 months after stress, which is stated in the FM guideline, and many preclinical studies, such as those analyzing molecular and cellular mechanisms, as well as additional evidence using different animal models, are required. Thus, the ICGP and IPGP models have the potential to help discover and characterize new therapeutic medicines that might be used for the radical treatment of FM, although there are several limitations to be overcome.

Assessing Ethnic Minority Representation in Fibromyalgia Clinical Trials: A Systematic Review of Recruitment Demographics

The under-representation of non-White participants in Western countries in clinical research has received increased attention, due to recognized physiological differences between ethnic groups, which may affect the efficacy and optimal dosage of some treatments. This review assessed ethnic diversity in pharmaceutical trials for fibromyalgia, a poorly understood chronic pain disorder. We also investigated longitudinal change to non-White participant proportions in trials and non-White participants' likelihood to discontinue with fibromyalgia research between trial stages (retention). First, we identified relevant trials conducted in the United States and Canada between 2000 and 2022, by searching PubMed, Web of Science, Scopus, and the Cochrane Library databases. In trials conducted both across the United States and Canada, and exclusively within the United States, approximately 90% of participants were White. A longitudinal analysis also found no change in the proportion of non-White participants in trials conducted across the United States and Canada between 2000 and 2022. Finally, we found no significant differences in trial retention between White and non-White participants. This review highlights the low numbers of ethnic minorities in fibromyalgia trials conducted in the United States and Canada, with no change to these proportions over the past 22 years. Furthermore, non-White participants were not more likely to discontinue with the fibromyalgia research once they were recruited.

Pregabalin alters reproductive performance in male mice and causes congenital anomalies in offspring

CONTEXT

Pregabalin is an anticonvulsant drug with analgesic activity for the treatment of neuropathic pain.

AIMS

To valuate the toxicity of pregabalin in reproductive parameters, spermatogenesis, and teratogenicity in the offspring of mice.

METHODS

Twenty male mice were randomly distributed into two groups: PGB group and group C (n =10 per group). The animals in the PGB group received, via gavage, 200mg/kg of pregabalin diluted in distilled water daily, for a period of 45days. Group C received distilled water under the same experimental design.

KEY RESULTS

In the paternal parameters of the PGB group, there was a significant increase in the size of the testicles, morphological alterations in the spermatozoa, a decrease in the Johnsen score, an increase in the Leydig cells, and a decrease in the serum level of testosterone. In the intrauterine development parameters of females mated with males from the PGB group, a significant decrease in placental weight, weight and length of fetuses, and fetal viability rate was observed. There was a significant increase in the number of resorptions and post-implantation losses. The significant anomalies observed in the offspring were alteration in the size of the kidneys, absent metacarpals and phalanges, alteration in the sternum, and supernumerary thoracic vertebrae.

CONCLUSION

Results suggest that pregabalin had toxic effects on the reproductive function of male mice and teratogenic potential.

IMPLICATIONS

The findings of this study may provide new hypotheses, taking into account the risk-benefit ratio for male reproduction and offspring health.

Beyond the Pain: A Systematic Narrative Review of the Latest Advancements in Fibromyalgia Treatment

Fibromyalgia is a complex chronic pain disorder that significantly impacts the quality of life of affected individuals. The etiology of fibromyalgia remains elusive, necessitating effective treatment options. This review aims to provide an overview of current treatment options for fibromyalgia and highlight recent updates in managing the condition. The methodology employed in this systematic review comprised the following key steps. We conducted a comprehensive search across various databases to identify pertinent studies published between 2000 and 2023. Inclusion criteria were defined to specifically target studies involving adult individuals diagnosed with fibromyalgia, with a focus on both pharmacological and non-pharmacological interventions for managing the condition. The review encompassed a range of study types, including randomized controlled trials, observational studies, and systematic reviews. To ensure the quality of the selected studies, we employed appropriate assessment tools, and data extraction and synthesis adhered to established guidelines. This rigorous approach allowed for a robust analysis of the literature on fibromyalgia management. In the course of our review, it became evident that a spectrum of treatment approaches holds significant promise in the management of fibromyalgia. Specifically, pharmacological interventions, including selective serotonin-norepinephrine reuptake inhibitors, anticonvulsants, cannabinoids, tropisetron, and sodium oxybate, have exhibited substantial potential in alleviating fibromyalgia symptoms. Concurrently, non-pharmacological strategies, such as cognitive-behavioral therapy, exercise regimens, and complementary and alternative therapies, have yielded positive outcomes in improving the condition's management. Recent developments in the field have introduced innovative pharmacological agents like milnacipran and pregabalin, in addition to non-pharmacological interventions like mindfulness-based stress reduction and aquatic exercise, expanding the array of options available to enhance fibromyalgia care and alleviating patient symptoms. Fibromyalgia necessitates a multidisciplinary approach to treatment, encompassing both pharmacological and non-pharmacological interventions. Recent updates in fibromyalgia management offer additional options to alleviate symptoms and improve the quality of life for individuals with fibromyalgia. Healthcare professionals should remain informed about these advancements to provide evidence-based care, addressing the complex symptoms associated with fibromyalgia and enhancing patient outcomes.

Short‑term effects of pregabalin plus exercise therapy on pain, emotional status, physical function and nociceptive responses in patients with fibromyalgia

The aim of the present study was to investigate the effects of pregabalin plus exercise vs. pregabalin treatment alone on the electromyographic nociceptive flexion reflex (NFR) threshold in patients with fibromyalgia (FM). For this purpose, the present study included a total of 40 patients diagnosed with FM according to the American College of Rheumatology 2010 criteria. The patients were divided into two groups as follows: Group 1 received pregabalin treatment only and group 2 received exercise therapy in addition to pregabalin treatment. Assessments were made at baseline and at the 1st month using a visual analog scale (VAS) to measure pain, the Fibromyalgia Impact Questionnaire (FIQ) to measure the severity of FM, Beck's Depression Inventory (BDI) to measure depression and the NFR to measure the compressive forces on peripheral nerves. In both groups, the NFR threshold following treatment was significantly higher than that at the baseline results (P#x003C;0.001). There was no significant difference between the groups as regards the difference from pre- to post-treatment NFR threshold values (P=0.610 and P=0.555, respectively). There was a strong, negative correlation between the pre-treatment NFR threshold and VAS resting, VAS motion and FIQ scores (Rho=-0.62, Rho=-0.69 and Rho=-0.60, respectively). There was a moderate negative correlation between the pre-treatment NFR threshold and BDI scores (Rho=-0.35). On the whole, the present study demonstrates that in the treatment of FM, pregabalin improves the clinical scores and leads to an increase in the NFR threshold. Herewith, it should be noted that short-term exercise therapy does not appear to provide additional benefits.

Gabapentinoids for Pain: A Review of Published Comparative Effectiveness Trials and Data Submitted to the FDA for Approval

Use of the gabapentinoids for pain continues to increase. In 2018, the US Food and Drug Administration (FDA) strengthened the warnings for both gabapentin and pregabalin to emphasize the central nervous system side effects and the risk of respiratory depression, especially when combined with other centrally acting drugs. We reviewed the published comparative effectiveness literature for gabapentinoids for pain as well as all trials (published and unpublished) used by the FDA for the approval of the five pain indications for these agents (one for gabapentin, four for pregabalin). Among the findings of interest are the fact that the FDA rejected the application for gabapentin for diabetic peripheral neuropathy based on the risk versus benefit profile of that drug in the clinical trials that were submitted by the manufacturer. Additionally, both the comparative effectiveness trials as well as the studies used by the FDA tend to be short in duration and show only modest pain benefits for the gabapentinoids. The placebo response in these trials was frequently one-third to one-half as great as the pain benefit demonstrated by the gabapentinoid. Based on the available clinical trial evidence, we feel prescribers should be cautious when using gabapentinoids for pain, particularly when using these agents for a prolonged period or when combined with other, centrally acting agents.

The risk of fragility fractures following initiation of gabapentin and pregabalin-A Danish, nationwide, high-dimensional propensity score-matched cohort study

Gabapentin and pregabalin have been associated with an increased risk of fragility fractures. Due to differences in pharmacokinetics, we aimed to assess the fracture-risk difference between the two medicines. We performed a Danish nationwide new user, high-dimensional propensity score-matched cohort study to assess the 90-day risk of fragility fractures among adults, from January 1996 to December 2018. We applied a high-dimensional propensity score to match new users of gabapentin with new users of pregabalin in a 1:1 intention-to-treat approach. Hazard ratios (HRs), incidence rates (IRs) and incidence rate difference (IRD) were obtained. We identified 388 236 eligible patients of which 294 223 and 98 869 initiated gabapentin and pregabalin, respectively. We included 48 272 matched pairs for further analysis. The mean age was 56 (IQR 44-69) years, and the average follow-up was approximately 11 500 person-years (PY). The IRs of fragility fractures were 23.7 (95%CI 21.0-26.7) and 23.2 (95%CI 20.5-26.2) per 1000 PY for gabapentin and pregabalin-exposed patients, respectively. This yielded an HR of 1.02 (95%CI 0.86-1.21) when using gabapentin as the intervention drug and pregabalin as the reference drug. The IRD was estimated to 0.5 PY (95%CI -3.5-4.5). In conclusion, short-term risk of fragility fractures among gabapentin initiators was not different compared to those initiating pregabalin.

Pregabalin administration in patients with fibromyalgia: a Bayesian network meta-analysis

Several studies investigated the effectiveness and the safety of different doses of pregabalin in fibromyalgia. However, the optimal protocol remains controversial. A Bayesian network meta-analysis comparing 300, 450, and 600 mg/daily of pregabalin for fibromyalgia was conducted. The literature search was conducted in January 2022. All the double-blind randomised clinical trials comparing two or more dose protocols of pregabalin for fibromyalgia were accessed. Studies enrolling less than 50 patients were not eligible, nor were those with a length of follow-up shorter than eight weeks. The outcomes of interests were: Fibromyalgia Impact Questionnaire (FIQ), sleep quality, and adverse events. The network meta-analyses were performed using the routine for Bayesian hierarchical random-effects model analysis, with log odd ratio (LOR) and standardized mean difference (SMD) effect measure. Data from 4693 patients (mean age 48.5 years) were retrieved. 93.1% (4370 of 4693 patients) were women. The median follow-up was 14.8 weeks. Pregabalin 450 mg/daily resulted in greater reduction in Fibromyalgia Impact Questionnaire (SMD - 1.83). Pregabalin 600 demonstrated the greatest sleep quality (SMD 0.15). Pregabalin 300 mg/daily evidenced the lowest rate of adverse events (LOR 0.12). The dose of pregabalin must be customised according to patients' characteristics and main symptoms.

The Pain Outcomes Comparing Yoga vs. Structured Exercise (POYSE) Trial in Veterans With Fibromyalgia: Study Design and Methods

Background

Fibromyalgia is a common pain condition that often leads to significant disability. Unfortunately, the effectiveness of most medications for fibromyalgia is limited, and there is a need for alternative, non-pharmacological therapies. Yoga and aerobic exercise are both evidence-based non-pharmacological treatments for fibromyalgia. However, no prior studies have directly compared the effectiveness of yoga vs. exercise.

Objective

This article describes the study design and recruitment outcomes of the Pain Outcomes comparing Yoga vs. Structured Exercise (POYSE) Trial, a two-arm randomized comparative effectiveness trial.

Methods

Veterans with fibromyalgia, defined by the 2010 American College of Rheumatology diagnostic criteria, who also experienced at least moderate pain severity were enrolled. The participants were randomized to a 12-week yoga-based or a structured exercise program (SEP) and will undergo comprehensive outcome assessments at baseline, 1, 3, 6, and 9 months by interviewers blinded to treatment assignment. The primary outcome will be the overall severity of fibromyalgia as measured by the total Fibromyalgia Impact Questionnaire-Revised. Secondary outcomes included depression, anxiety, health-related quality of life, pain beliefs, fatigue, sleep, and self-efficacy.

Results

A total of 2,671 recruitment letters were sent to potential participants with fibromyalgia. Of the potential participants, 623 (23.3%) were able to be contacted by telephone and had their eligibility assessed. Three hundred seventy-one of those interviewed were found to be eligible (59.6%) and 256 (69.0%) agreed to participate and were randomized to the YOGA (n = 129) or the SEP (n = 127) arm of the trial.

Conclusions

Clinicians are faced with numerous challenges in treating patients with fibromyalgia. The interventions being tested in the POYSE trial have the potential to provide primary care and other care settings with new treatment options for clinicians while simultaneously providing a much needed relief for patients suffering from fibromyalgia.

Trial Registration

Funded by VA Rehabilitation Research and Development (D1100-R); Trial registration: ClinicalTrials.gov, NCT01797263.

Comparative efficacy of amitriptyline, duloxetine and pregabalin for treating fibromyalgia in adults: an overview with network meta-analysis

Treatment recommendations for fibromyalgia (FM) include a range of predominantly pharmacological treatment options designed to ensure the maintenance of symptoms and improvement in the quality of life of these patients. Our aim is to identify and compare the efficacy of amitriptyline (AMT), duloxetine (DLX), and pregabalin (PGB) for reducing pain intensity by 30% (R30%) and 50% (R50%) in adult patients with fibromyalgia. The review was conducted in the Medline/PubMed, Cochrane Library, and Embase databases up to February 2022. This study included systematic reviews (SR) of randomized clinical trials (RCTs) targeting adult patients over 18 years of age diagnosed with fibromyalgia according to the criteria of scientific societies, which include the basic clinical diagnosis characterized by the presence of pressure sensitivity in at least 11 of the 18 tender points, in addition to the presence of widespread musculoskeletal pain for a period longer than 3 months and a general assessment of the patient's health status. Pregnant women and children or adolescents were excluded. The Rob 2.0 tool from the Cochrane Collaboration was used to assess the risk of bias in RCTs. The quality of evidence of the reviews included was assessed according to the Grading of Recommendations Assessment, Development and Evaluation-GRADE. A meta-analysis for the evidence network was performed using the Bayesian approach, which allows simultaneous comparison of all treatment options (medication and dose). The different treatments were ranked according to the response rate according to the surface under the curve (SUCRA), which was expressed as a percentage. The results were presented in tables and figures. The protocol with the detailed methods was registered in PROSPERO (CRD42021229264). Eight systematic reviews were identified, and, from these, 15 clinical trials comparing AMT (n = 273), DLX (n = 2595), and PGB (n = 3,506) against placebo were selected. For the outcome R30%, PGB 450 mg was superior to DLX 30 mg and PGB 150 mg, while DLX 20 mg and 30 mg were not superior to placebo. For the outcome R50%, AMT 25 mg was superior to all other alternatives evaluated. The calculation of the SUCRA indicated that PGB 450 mg was the best performance option for R30% and AMT 25 mg for R50%. PGB 150 mg was the drug with the worst performance in the two outcomes evaluated. The drugs evaluated showed benefits for pain reduction in patients with fibromyalgia. In the absence of direct comparison studies, indirect comparison meta-analyses are an important resource for assisting in clinical decision-making. Our data only provide an indicator of the effectiveness of the three drugs evaluated, but as with other health conditions, tolerability and safety are important for the decision-making process and clinical management. In this regard, we encourage caution in interpreting our data.

Advances in the management of fibromyalgia: what is the state of the art?

INTRODUCTION

Fibromyalgia (FM) is a chronic pain syndrome associated with fatigue, insomnia, dyscognition, and emotional distress. Critical illness mechanisms include central sensitization to nociceptive and non-nociceptive stimuli often resulting in hypersensitivity to all sensory input.

AREAS COVERED

The clinical presentation of FM can vary widely and therefore requires therapies tailored to each patient's set of symptoms. This manuscript examines currently prescribed therapeutic approaches supported by empirical evidence as well as promising novel treatments. Although pharmacological therapy until now has been only moderately effective for FM symptoms, it represents a critical component of every treatment plan.

EXPERT OPINION

Currently approved pharmacological therapies for FM symptoms have limited but proven effectiveness. Novel therapies with cannabinoids and naltrexone appear promising. Recent functional imaging studies of FM have discovered multiple brain network abnormalities that may provide novel targets for mechanism-based therapies. Future treatment approaches, however, need to improve more than clinical pain but also other FM domains like fatigue, insomnia, and distress.

Outcomes of a Comprehensive Pain Rehabilitation Program for Patients With Fibromyalgia

OBJECTIVE

To analyze opioid intake interference with psychological, well-being, and functional outcomes and medication tapering in patients with fibromyalgia admitted to the Mayo Clinic Pain Rehabilitation Program (MCPRP) in Florida.

PATIENTS AND METHODS

A retrospective study on MCPRP outcomes was conducted. We reviewed the health records of 150 patients with fibromyalgia who participated in the program from May 1, 2014, to May 1, 2015. All patients were asked to fill out a survey at admission to and dismissal from the program. Surveys contained questions from the numeric pain score, Multidimensional Pain Inventory (perceived life control and interference of pain subscales), Center for Epidemiological Studies-Depression Scale, Pain Catastrophizing Scale, 36-Item Short-Form Health Status Survey (general health perceptions subscale), and Pain Self-Efficacy Questionnaire. A medical record review identified categories and number of medications at program admission and dismissal. Patients were divided in 2 groups: those whose concomitant medication did not include opioids at admission (no opioids group) and those whose concomitant medication included opioids at admission (opioids group).

RESULTS

By dismissal from the MCPRP, patients with fibromyalgia in the no opioids group had a significant (P<.05) improvement in all the self-reported scores. Medication, including opioids, were effectively tapered at a substantially higher percentage in the opioids group.

CONCLUSION

Benefit of the comprehensive pain rehabilitation program in patients with fibromyalgia was indicated by clinical improvements in pain severity, physical and emotional health, and functional capacity while successfully tapering medication. Opioid intake at admission may modify the program outcomes.

Why It Is Important to Consider the Effects of Analgesics on Sleep: A Critical Review

We review the known physiological mechanisms underpinning all of pain processing, sleep regulation, and pharmacology of analgesics prescribed for chronic pain. In particular, we describe how commonly prescribed analgesics act in sleep-wake neural pathways, with potential unintended impact on sleep and/or wake function. Sleep disruption, whether pain- or drug-induced, negatively impacts quality of life, mental and physical health. In the context of chronic pain, poor sleep quality heightens pain sensitivity and may affect analgesic function, potentially resulting in further analgesic need. Clinicians already have to consider factors including efficacy, abuse potential, and likely side effects when making analgesic prescribing choices. We propose that analgesic-related sleep disruption should also be considered. The neurochemical mechanisms underlying the reciprocal relationship between pain and sleep are poorly understood, and studies investigating sleep in those with specific chronic pain conditions (including those with comorbidities) are lacking. We emphasize the importance of further work to clarify the effects (intended and unintended) of each analgesic class to inform personalized treatment decisions in patients with chronic pain. © 2021 American Physiological Society. Compr Physiol 11:1-31, 2021.

Placebo effect in pharmacological management of fibromyalgia: a meta-analysis

INTRODUCTION

The management of fibromyalgia involves a combination of pharmacological and non-pharmacological treatments.

SOURCE OF DATA

Recently published literature in PubMed, Google Scholar and Embase databases.

AREAS OF AGREEMENT

Several pharmacological and non-pharmacological strategies have been proposed for the management of fibromyalgia. However, the management of fibromyalgia remains controversial. The administration of placebo has proved to be more effective than no treatment in many clinical settings and evidence supports the 'therapeutic' effects of placebo on a wide range of symptoms.

AREAS OF CONTROVERSY

The placebo effect is believed to impact the clinical outcomes, but its actual magnitude is controversial.

GROWING POINTS

A meta-analysis comparing pharmacological management versus placebo administration for fibromyalgia was conducted.

AREAS TIMELY FOR DEVELOPING RESEARCH

Drug treatment resulted to be more effective than placebo administration for the management of fibromyalgia. Nevertheless, placebo showed a beneficial effect in patients with fibromyalgia. Treatment-related adverse events occurred more frequently in the drug treatment.

LEVEL OF EVIDENCE

I, Bayesian network meta-analysis of double-blind randomized clinical trials.

The Role of Vitamin D in the Management of Chronic Pain in Fibromyalgia: A Narrative Review

INTRODUCTION

Fibromyalgia (FM) is a complex disorder characterized primarily by chronic, widespread musculoskeletal pain. Currently, the Food and Drug Administration (FDA) has approved the use of three medications to treat FM: pregabalin, duloxetine, and milnacipran. The pharmaceutical intervention has lacked consistent pain relief among all patients. Therefore, the investigation into alternative treatment options has grown in interest. This narrative review aims to evaluate the evidence regarding vitamin D for the treatment of FM.

METHODS

Narrative review.

RESULTS

Low serum vitamin D has been linked to various chronic pain states. An association between vitamin D deficiency and FM has been reported but is controversial in the literature. Some studies have documented the beneficial effects of vitamin D supplementation on reducing pain symptoms and improving the overall quality of life in those with FM. Despite these positive findings, many of the studies regarding this topic lack adequate power to make substantial conclusions about the effects of vitamin D on FM.

CONCLUSION

Existing studies provide promising results. However, additional high-quality data on vitamin D supplementation is needed before recommendations for pain management can be made. Vitamin D supplementation is inexpensive, has minimal side effects, and can benefit FM patients regardless of its efficacy in pain control. Additionally, high-quality studies are warranted to fully elucidate the potential of vitamin D to manage chronic pain in FM.

A comparison of the effects of fire needle and routine acupuncture for myofascitis: A protocol for systematic review and meta-analysis

BACKGROUND

Myofascitis is a common disease in clinic. The main cause of the disease is aseptic inflammation of local muscles and connective tissues such as myofascial, which can be manifested as paralysis, distension, and other discomfort, local muscle stiffness, spasm or palpable strain-like nodules. Chinese medicine ascribes it to "bi disease" and "Arthralgia disease," while Western medicine believes that the disease is mainly due to local muscle and fascia edema and exudation caused by trauma or long-term strain, forcing nerves to jam and producing pain and other abnormal feelings. Although the disease is not life-threatening, the pain and distension caused by local inflammatory stimuli can affect the patient's daily life and sleep quality. The purpose of this systematic review is to evaluate the efficacy of fire needle vs routine acupuncture in the treatment of myofascitis.

METHODS

Randomized controlled trials (RCTS) of fire needle vs routine acupuncture for myofascial inflammation will be comprehensively searched from inception to September 2020 on PubMed, Embase, Cochrane Library, China Biomedical Literature (CBM), China National Knowledge Infrastructure (CNKI), Chongqing VIP (CQVIP), and Wanfang. Additionally, RCT registered sites, including http://www.ClinicalTrials.gov and http://www.chictr.org.cn, also will be the search. Visual analogue scale (VAS) was used to score the pain before and after treatment. The primary outcome will be to compare the difference in pain scores between the 2 interventions. Two independent authors filtered the literature in the above database, extracted the data, and cross-checked it.

RESULTS

This study will offer a reasonable comprehensive evidence for the treatment of myofascitis with fire needle.

CONCLUSION

The conclusion of this study will provide evidence to judge the effectiveness of fire needle on myofascitis.

REGISTRATION NUMBER

INPLASY202080034.

Extraction of Pregabalin in Urine Samples Using a Sulfonated Poly(ether ether ketone) Membrane

In this work, a simple polymer-assisted microextraction technique was developed to determine pregabalin (an anticonvulsant drug) in the urine sample. A sulfonated poly(ether ether ketone) membrane was used as a sorbent for pregabalin extraction, and the extraction performance was compared with that of the conventional polydimethylsiloxane membrane. The extraction device is free moving and tumbles continuously throughout the stirred sample solution during extraction to enhance the extraction efficiency. The electrostatic interactions between the sulfonic-acid-functionalized polymeric membrane and the amine group in the pregabalin molecule facilitate higher preconcentration factor at a shorter extraction time. Optimizing conditions of the extraction method were investigated to obtain higher extraction efficiency. The developed method exhibited good linearity in the range of 0.05 to 2 µg/mL with a correlation of determination (r 2) 0.9998, acceptable limits of detection, limits of quantification, and preconcentration factor of 105-fold. The within-day and between-day precisions of pregabalin were lower than 7% relative standard deviations. Pregabalin was extracted from urine samples with recoveries of >92%, and no significant matrix effects were observed.

BMI but not age and sex negatively impact on the outcome of pharmacotherapy in fibromyalgia: a systematic review

INTRODUCTION

The impact of sex, age, body mass index (BMI) in fibromyalgia is still unclear. A systematic review was conducted to investigate whether sex, age and BMI influence the clinical outcomes and rate of adverse events.

METHODS

The present study was performed according to the PRISMA guidelines. The literature search was performed in February 2021. All the RCTs investigating pharmacological strategies for fibromyalgia were accessed.

RESULTS

Data from 51 RCTs (17,311 patients) were collected. Short Form 36 emotional, Social function and physical role subscales showed evidence of a negative association with BMI (P = 0.02, P = 0.002 and P = 0.0001, respectively). Depression and anxiety subscales of the Hospital Anxiety and Depression score demonstrated evidence of a positive association with age (P = 0.04 and P = 0.001, respectively) and sex (P = 0.00005 and P = 0.0001, respectively). Visual analog scale evidenced a positive association with BMI (P = 0.04). Clinical Global Impression Severity scale demonstrated evidence of a negative association with BMI (P = 0.02).

CONCLUSION

Irrespective from the pharmacological approach, a higher BMI is negatively associated with a favorable outcome in patients with fibromyalgia. The association with sex and age remains controversial.

LEVEL OF EVIDENCE

I, systematic review of RCTs.

Double-blind, randomized, placebo-controlled crossover trial of alpha-lipoic acid for the treatment of fibromyalgia pain: the IMPALA trial

ABSTRACT

Fibromyalgia is a common and challenging chronic pain disorder with few, if any, highly effective and well-tolerated treatments. Alpha-lipoic acid (ALA) is a nonsedating antioxidant with evidence of efficacy in the treatment of symptomatic diabetic neuropathy that has not been evaluated in the setting of fibromyalgia treatment. Thus, we conducted a single-centre, proof-of-concept, randomized, placebo-controlled, crossover trial of ALA for the treatment of fibromyalgia. Twenty-seven participants were recruited, and 24 participants completed both treatment periods of the trial. The median maximal tolerated dose of ALA in this trial was 1663 mg/day. Treatment-emergent adverse events with ALA were infrequent and not statistically different from placebo. For the primary outcome of pain intensity, and for several other validated secondary outcomes, there were no statistically significant differences between placebo and ALA. A post hoc exploratory subgroup analysis showed a significant interaction between gender and treatment with a significant favourable placebo-ALA difference in pain for men, but not for women. Overall, the results of this trial do not provide any evidence to suggest promise for ALA as an effective treatment for fibromyalgia, which is predominantly prevalent in women. This negative clinical trial represents an important step in a collective strategy to identify new, better tolerated and more effective treatments for fibromyalgia.

Central sensitisation in chronic pain conditions: latest discoveries and their potential for precision medicine

Chronic pain is a leading cause of disability globally and associated with enormous health-care costs. The discrepancy between the extent of tissue damage and the magnitude of pain, disability, and associated symptoms represents a diagnostic challenge for rheumatology specialists. Central sensitisation, defined as an amplification of neural signalling within the CNS that elicits pain hypersensitivity, has been investigated as a reason for this discrepancy. Features of central sensitisation have been documented in various pain conditions common in rheumatology practice, including fibromyalgia, osteoarthritis, rheumatoid arthritis, Ehlers-Danlos syndrome, upper extremity tendinopathies, headache, and spinal pain. Within individual pain conditions, there is substantial variation among patients in terms of presence and magnitude of central sensitisation, stressing the importance of individual assessment. Central sensitisation predicts poor treatment outcomes in multiple patient populations. The available evidence supports various pharmacological and non-pharmacological strategies to reduce central sensitisation and to improve patient outcomes in several conditions commonly seen in rheumatology practice. These data open up new treatment perspectives, with the possibility for precision pain medicine treatment according to pain phenotyping as a logical next step. With this view, studies suggest the possibility of matching non-pharmacological approaches, or medications, or both to the central sensitisation pain phenotypes.

Efficacy and Safety of Pregabalin for Fibromyalgia in a Population of Chinese Subjects

PURPOSE

Fibromyalgia (FM) may go underdiagnosed and untreated in China in part due to a lack of awareness and understanding of the condition, and limited available treatments.

PATIENTS AND METHODS

This randomized, double-blind, Phase III local registration trial compared the efficacy and safety of pregabalin (flexibly dosed 300-450 mg/day) versus placebo for the management of pain in Chinese adults diagnosed with FM according to American College of Rheumatology 1990 criteria, across 22 centers within China. Patients reported pain score of ≥40 mm on 100-mm scale (from 0 "no pain" to 100 "worst possible pain"). The primary efficacy endpoint was change from baseline to Week 14 in mean pain score (MPS). Secondary endpoints included measures of sleep and sleep interference. Safety and tolerability were monitored throughout.

RESULTS

Median pregabalin dose was 335 mg/day. A significant reduction from baseline to Week 14 in weekly MPS was seen for patients treated with pregabalin (n=170) versus placebo (n=164) (least-squares mean difference [95% confidence interval]: -0.73 [-1.10 to -0.36]; P=0.0001). Significantly greater proportions of patients experienced ≥30% and ≥50% reductions in MPS at Week 14 with pregabalin versus placebo. Pregabalin-treated subjects demonstrated improvements in measures of sleep and sleep interference. Pregabalin was generally well tolerated. The most common adverse events were dizziness and somnolence; no serious adverse events (SAEs) occurred in pregabalin-treated subjects. Nine placebo-treated subjects experienced SAEs.

CONCLUSION

Pregabalin (300-450 mg/day) is a safe and effective treatment for reducing pain and improving sleep in native Chinese subjects with FM.

CLINICALTRIALSGOV IDENTIFIER

NCT01387607.

Cognitive behavioral therapy for insomnia in patients with chronic pain - A systematic review and meta-analysis of randomized controlled trials

Several randomized controlled trials have implemented cognitive behavioral therapy for insomnia (CBT-I) for patients with comorbid insomnia and chronic pain. This systematic review and meta-analysis investigated the effectiveness of CBT-I on patient-reported sleep, pain, and other health outcomes (depressive symptoms, anxiety symptoms, and fatigue) in patients with comorbid insomnia and chronic non-cancer pain. A systematic literature search was conducted using eight electronic databases. Upon duplicate removal, 6374 records were screened against the inclusion criteria. Fourteen randomized controlled trials were selected for the review, with twelve (N = 762 participants) included in the meta-analysis. At post-treatment, significant treatment effects were found on global measures of sleep (standardized mean difference = 0.89), pain (0.20), and depressive symptoms (0.44). At follow-up (up to 12 mo), CBT-I significantly improved sleep (0.56). Using global measures of sleep, we found a probability of 81% and 71% for having better sleep after CBT-I at post-treatment and final follow-up, respectively. The probability of having less pain after CBT-I at post-treatment and final follow-up was 58% and 57%, respectively. There were no statistically significant effects on anxiety symptoms and fatigue at either assessment point. Future trials with sufficient power, longer follow-up periods, and inclusion of CBT for pain components are warranted.

Association of Therapies With Reduced Pain and Improved Quality of Life in Patients With Fibromyalgia: A Systematic Review and Meta-analysis

IMPORTANCE

Fibromyalgia is a chronic condition that results in a significant burden to individuals and society.

OBJECTIVE

To investigate the effectiveness of therapies for reducing pain and improving quality of life (QOL) in people with fibromyalgia.

DATA SOURCES

Searches were performed in the MEDLINE, Cochrane, Embase, AMED, PsycInfo, and PEDro databases without language or date restrictions on December 11, 2018, and updated on July 15, 2020.

STUDY SELECTION

All published randomized or quasi-randomized clinical trials that investigated therapies for individuals with fibromyalgia were screened for inclusion.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted data and assessed risk of bias using the 0 to 10 PEDro scale. Effect sizes for specific therapies were pooled using random-effects models. The quality of evidence was assessed using the Grading of Recommendations Assessment (GRADE) approach.

MAIN OUTCOMES AND MEASURES

Pain intensity measured by the visual analog scale, numerical rating scales, and other valid instruments and QOL measured by the Fibromyalgia Impact Questionnaire.

RESULTS

A total of 224 trials including 29 962 participants were included. High-quality evidence was found in favor of cognitive behavioral therapy (weighted mean difference [WMD], -0.9; 95% CI, -1.4 to -0.3) for pain in the short term and was found in favor of central nervous system depressants (WMD, -1.2 [95% CI, -1.6 to -0.8]) and antidepressants (WMD, -0.5 [95% CI, -0.7 to -0.4]) for pain in the medium term. There was also high-quality evidence in favor of antidepressants (WMD, -6.8 [95% CI, -8.5 to -5.2]) for QOL in the short term and in favor of central nervous system depressants (WMD, -8.7 [95% CI, -11.3 to -6.0]) and antidepressants (WMD, -3.5 [95% CI, -4.5 to -2.5]) in the medium term. However, these associations were small and did not exceed the minimum clinically important change (2 points on an 11-point scale for pain and 14 points on a 101-point scale for QOL). Evidence for long-term outcomes of interventions was lacking.

CONCLUSIONS AND RELEVANCE

This systematic review and meta-analysis suggests that most of the currently available therapies for the management of fibromyalgia are not supported by high-quality evidence. Some therapies may reduce pain and improve QOL in the short to medium term, although the effect size of the associations might not be clinically important to patients.

Efficacy of pregabalin as a monotherapy versus combined pregabalin and milnacipran in the management of fibromyalgia

AIM

To compare the efficacy and tolerability of combined pregabalin (PGB) and milnacipran (MLN) in female patients with fibromyalgia (FM) versus PGB as a monotherapy.

METHODS

The present randomized open study included 58 female patients diagnosed with FM (registered on 4/2/19: NCT03905486). Patients were randomly divided into 2 groups (2:2); group 1 included 29 patients who received PGB monotherapy (150 mg twice daily) and group 2 included 29 patients who received combined PGB (150 mg twice daily) and MLN (50 mg twice daily) for 3 months. At the initial visit, patients were subjected to demographic data collection and assessed by the visual analog scale (VAS) for pain and the FM impact questionnaire (FIQ). Outcome measures after 3 months: FIQ, VAS and Leeds Sleep Evaluation Questionnaire.

RESULTS

The median disease duration was 2 years in group 1 (6 months to 5 years) and 2 years in group 2 (6 months to 12 years). The dropout rate was 20.7% in group 1 (n = 6) and 10.3% in group 2 (n = 3). At the follow-up evaluation, a statistically significant improvement was observed in VAS and FIQ scores in both groups (P < 0.001). Although the percentage of patients demonstrating significant improvement in pain, disease impact and sleep pattern were higher in group 2, this did not reach statistical significance.

CONCLUSION

Although PGB as a monotherapy and in combination with MLN have both shown adequate efficacy in the treatment of patients with FM, the combined therapy did not demonstrate superiority over the monotherapy.

Cannabis and cannabidiol (CBD) for the treatment of fibromyalgia

Fibromyalgia is a complex disease process that is as prevalent as it is poorly understood. Research into the pathophysiology is ongoing, and findings will likely assist in identifying new therapeutic options to augment those in existence today that are still insufficient for the care of a large population of patients. Recent evidence describes the use of cannabinoids in the treatment of fibromyalgia. This study provides a systematic, thorough review of the evidence alongside a review of the seminal data regarding the pathophysiology, diagnosis, and current treatment options. Fibromyalgia is characterized by widespread chronic pain, fatigue, and depressive episodes without an organic diagnosis, which may be prevalent in up to 10% of the population and carries a significant cost in healthcare utilization, morbidity, a reduced quality of life, and productivity. It is frequently associated with psychiatric comorbidities. The diagnosis is clinical and usually prolonged, and diagnostic criteria continue to evolve. Some therapies have been previously described, including neuropathic medications, milnacipran, and antidepressants. Despite some level of efficacy, only physical exercise has strong evidence to support it. Cannabis has been used historically to treat different pain conditions since ancient times. Recent advances allowed for the isolation of the active substances in cannabis and the production of cannabinoid products that are nearly devoid of psychoactive influence and provide pain relief and alleviation of other symptoms. Many of these, as well as cannabis itself, are approved for use in chronic pain conditions. Evidence supporting cannabis in chronic pain conditions is plentiful; however, in fibromyalgia, they are mostly limited. Only a handful of randomized trials exists, and their objectivity has been questioned. However, many retrospective trials and patient surveys suggest the significant alleviation of pain, improvement in sleep, and abatement of associated symptoms. Evidence supporting the use of cannabis in chronic pain and specifically in fibromyalgia is being gathered as the use of cannabis increases with current global trends. While the current evidence is still limited, emerging data do suggest a positive effect of cannabis in fibromyalgia. Cannabis use is not without risks, including psychiatric, cognitive, and developmental as well as the risks of addiction. As such, clinical judgment is warranted to weigh these risks and prescribe to patients who are more likely to benefit from this treatment. Further research is required to define appropriate patient selection and treatment regimens.

Silver acupuncture for myofascitis: A protocol for systematic review and meta-analysis

BACKGROUND

This systematic review aims to evaluate the effectiveness and safety of silver acupuncture in treatment of myofascitis.

METHODS

Electronic databases of all silver acupuncture for myofascitis will be searched at PubMed, Cochrane Library, Springer, Embase, China National Knowledge Infrastructure, Wanfang, and Chinese Biological Medical disc from inception to March 31, 2020, with language restricted in Chinese and English. The primary outcome is visual analog scale, a short pain scale with sensitivity and comparability. Secondary outcomes included Clinical Assessment Scale for Cervical Spondylosis, Japanese Orthopaedic Association Scores, Oswestry dysfunction index, American Orthopaedic Foot and Ankle Society-Ankle Hindfoot scale, Foot and Ankle Ability Measure, The Cumberland ankle instability tool, Pittsburgh sleep quality index, self-rating anxiety scale, self-depression rating scale, and follow-up relapse rate. The systematic review and searches for randomized controlled trials of this therapy for myofascitis. The Cochrane RevMan V5.3 bias assessment tool is implemented to assess bias risk, data integration risk, meta-analysis risk, and subgroup analysis risk (if conditions are met). Mean difference, standard mean deviation, and binary data will be used to represent continuous results.

RESULTS

This study will provide a comprehensive review and evaluation of the available evidence for the treatment of myofascitis with this therapy.

CONCLUSION

This study will provide new evidence to evaluate the effectiveness and side effects of silver acupuncture for myofascitis. Due to the data are not personalized, no formal ethical approval is required.

ETHICS AND DISSEMINATION

There is no requirement of ethical approval and it will be in print or disseminated by electronic copies.

PROSPERO REGISTRATION NUMBER

CRD42020151476.

Postmortem analysis of quetiapine and pregabalin in human bone

In this study quetiapine and pregabalin were analyzed in human bones. A method previously developed for the determination of antidepressants in human bone was tested for the analysis of these two substances. Bones were pulverized and subjected to the extraction protocol, and after undergoing solid-phase extraction, samples were analyzed using gas chromatography-mass spectrometry. The assay was validated in the range 0.3-500 ng/mg, mean analytical recovery was 76.9% for quetiapine and 90.9% for pregabalin, matrix effect was 83% for quetiapine and 91% for pregabalin and process efficiency was 63.8% for quetiapine and 82.7% for pregabalin. The intra- and inter-day precision was below 3% in all cases and the intra- and inter-assay accuracy values were in almost all cases better than 12%. The validated method was then applied to bone samples from forensic cases. Drugs were detected in bone in 2 of the 3 blood positive cases. The approximate concentrations in bone were 40 ng/mg for pregabalin and 7 ng/mg for quetiapine. To our knowledge, this is the first time these substances were detected in bones. With this study the number of substances with a validated protocol to be used in human bones in case of necessity is expanded.

Current and Emerging Pharmacotherapy for Fibromyalgia

Introduction. Fibromyalgia syndrome (FMS) is a pain disorder with an estimated prevalence of 1–5%. It is associated with a variety of somatic and psychological disorders. Its exact pathogenesis is still unclear but is involved with neural oversensitization and decreased conditioned pain modulation (CPM), combined with cognitive dysfunction, memory impairment, and altered information processing. Connectivity between brain areas involved in pain processing, alertness, and cognition is increased in the syndrome, making its pharmacologic therapy complex. Only three drugs, pregabalin, duloxetine, and milnacipran are currently FDA-approved for FM treatment, but many other agents have been tested over the years, with varying efficacy. Areas Covered. The purpose of this review is to summarize current clinical experience with different pharmacologic treatments used for fibromyalgia and introduce future perspectives in developing therapies. Expert Opinion. Future insights into the fields of cannabinoid and opioid research, as well as an integrative approach towards the incorporation of genetics and functional imaging combined with additional fields of research relevant towards the study of complex CNS disorders, are likely to lead to new developments of novel tailor-made treatments for FMS patients.

Chronic Pain and Sleep Disturbances: A Pragmatic Review of Their Relationships, Comorbidities, and Treatments

Objective

The objective of this review is to answer three questions: 1) How are chronic pain severity and pain duration affected in patients with chronic pain and sleep disturbances that occur simultaneously? 2) What are common comorbidities and pain-related symptoms seen in patients with chronic pain and sleep disturbances? and 3) What are potentially effective pharmacological and nonpharmacological treatment options for both conditions?

Methods

Ovid Medline and PubMed were searched. Search terms included sleep wake disorder, chronic pain, fibromyalgia, treatment outcome, psychotherapy, complementary therapies, and therapeutics. Studies that assessed outcomes between individuals with chronic pain and those with concurrent chronic pain and sleep disturbances were included. Randomized controlled clinical trials of treatments for both conditions were included.

Results

Sixteen studies indicated that patients with both chronic pain and sleep disturbances have greater pain severity, longer duration of pain, greater disability, and are less physically active than those without sleep disturbances. Patients with both conditions are more likely to have concurrent depression, catastrophizing, anxiety, and suicidal ideation. Thirty-three randomized controlled trials assessed treatment for both chronic pain and sleep disturbances. Pregabalin was the most frequently studied medication, showing improvement in pain and sleep symptoms. Cognitive behavioral therapy for insomnia showed long-term improvement in sleep for patients with chronic pain.

Conclusions

Individuals with chronic pain and sleep disturbances have greater symptom severity, longer duration of symptoms, more disability, and additional comorbidities. Pharmacological and nonpharmacological treatments may be useful in the treatment of concurrent chronic pain and sleep disturbances, but further study is needed.

Natural polyphenols for the prevention of irritable bowel syndrome: molecular mechanisms and targets; a comprehensive review

Irritable bowel syndrome (IBS) is a well diagnosed disease, thoroughly attributed to series of symptoms criteria that embrace a broad range of abdominal complainers. Such criteria help to diagnosis the disease and can guide controlled clinical trials to seek new therapeutic agents. Accordingly, a verity of mechanisms and pathophysiological conditions including inflammation, oxidative stress, lipid peroxidation and different life styles are involved in IBS. Predictably, diverse therapeutic approaches are available and prescribed by clinicians due to major manifestations (i.e., diarrhea-predominance, constipation-predominance, abdominal pain and visceral hypersensitivity), psychological disturbances, and patient preferences between herbal treatments versus pharmacological therapies, dietary or microbiological approaches. Herein, we gathered the latest scientific data between 1973 and 2019 from databases such as PubMed, Google Scholar, Scopus and Cochrane library on relevant studies concerning beneficial effects of herbal treatments for IBS, in particular polyphenols. This is concluded that polyphenols might be applicable for preventing IBS and improving the IBS symptoms, mainly through suppressing the inflammatory signaling pathways, which nowadays are known as novel platform for the IBS management. Graphical abstract.

Customized Novel Design of 3D Printed Pregabalin Tablets for Intra-Gastric Floating and Controlled Release Using Fused Deposition Modeling

Three-dimensional (3D) printing has been recently employed in the design and formulation of various dosage forms with the aim of on-demand manufacturing and personalized medicine. In this study, we formulated a floating sustained release system using fused deposition modeling (FDM). Filaments were prepared using hypromellose acetate succinate (HPMCAS), polyethylene glycol (PEG 400) and pregabalin as the active ingredient. Cylindrical tablets with infill percentages of 25%, 50% and 75% were designed and printed with the FDM printer. An optimized formulation (F6) was designed with a closed bottom layer and a partially opened top layer. Filaments and tablets were characterized by means of fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and thermogravimetric analysis (TGA). The results show that the processing condition did not have a significant effect on the stability of the drug and the crystallinity of the drug remained even after printing. A dissolution study revealed that drug release is faster in an open system with low infill percentage compared to closed systems and open systems with a high infill ratio. The optimized formulation (F6) with partially opened top layer showed zero-order drug release. The results show that FDM printing is suitable for the formulation of floating dosage form with the desired drug release profile.

A Systematic Review of Studies Using the Multidimensional Assessment of Fatigue Scale

PURPOSE

To review how the Multidimensional Assessment of Fatigue (MAF) has been used and evaluate its psychometric properties.

METHODS

We conducted a database search using "multidimensional assessment of fatigue" or "MAF" as key terms from 1993 to 2015, and located 102 studies.

RESULTS

Eighty-three were empirical studies and 19 were reviews/evaluations. Research was conducted in 17 countries; 32 diseases were represented. Nine language versions of the MAF were used. The mean of the Global Fatigue Index ranged from 10.9 to 49.4. The MAF was reported to be easy-to-use, had strong reliability and validity, and was used in populations who spoke languages other than English.

CONCLUSION

The MAF is an acceptable assessment tool to measure fatigue and intervention effectiveness in various languages, diseases, and settings across the world.

Efficacy and safety of mirogabalin for the treatment of fibromyalgia: results from three 13-week randomized, double-blind, placebo- and active-controlled, parallel-group studies and a 52-week open-label extension study

Objective: To investigate the efficacy and safety of mirogabalin, an α₂δ ligand, in patients with fibromyalgia (FM). Methods: In three 13-week, multicenter, double-blind, phase 3 studies (studies A, B, and C), patients with FM (n = 1293, 1270, and 1301, respectively) were randomized (1:1:1:1) to placebo, pregabalin 150 mg twice daily, mirogabalin 15 mg once daily or mirogabalin 15 mg twice daily. The primary endpoint was the change in weekly average daily worst pain score (ADPS) at week 13. Key secondary endpoints included Patient Global Impression of Change and change in the Fibromyalgia Impact Questionnaire total score. Long-term safety of mirogabalin was assessed in a 52-week extension study. Results: Neither mirogabalin dose demonstrated a significant ADPS reduction from baseline vs. placebo at week 13 in any of the three studies. Pregabalin significantly reduced ADPS from baseline vs. placebo in studies B and C (p = .0008 and .0001, respectively). The effect of mirogabalin compared with placebo on key secondary endpoints was variable across the studies. Mirogabalin was well tolerated by most patients in the phase 3 studies; no unexpected adverse events occurring during the 52-week extension study. Conclusion: While both mirogabalin doses were well tolerated by most patients and showed potential for reducing pain associated with FM, the primary endpoint of significant pain reduction in patients on mirogabalin compared with placebo was not achieved in any of the three randomized controlled studies. Clinical trial registration: NCT02146430; NCT02187159; NCT02187471; and NCT02234583 (extension study).

Application of ICD-11 among individuals with chronic pain: A post hoc analysis of the Stanford Self-Management Program

BACKGROUND

Chronic primary pain (CPP) is one of seven diagnostic groups within the proposed classification of chronic pain in ICD-11. Our aims were to apply the proposed ICD-11 criteria in a large cohort of chronic pain patients participating in the Chronic Pain Self-Management Program (CPSMP) and further investigate whether participants with CPP differed from participants with chronic secondary pain (CSP) regarding health, health expenditure and the effect of participating in the CPSMP.

METHODS

A secondary analysis of a randomized, controlled trial on the effect of the CPSMP. Four examiners categorized participants' pain according to ICD-11 using register-based medical diagnoses and patients' self-reported symptoms. Afterwards, differences between CPP and CSP were examined.

RESULTS

Out of 394 participants, 312 were successfully classified into CPP (n = 164) or CSP (n = 148) whereas 76 had a mixed pain condition. Participants with CPP were younger, more likely to be women, and had longer pain duration compared to participants with CSP. Participants with CPP reported worse health-related quality of life on the SF-36 Mental Component Summary and subscales of vitality, social functioning and bodily pain. Participants with CSP had more physical comorbidities and higher total health expenditure. None of the groups benefitted from the CPSMP.

CONCLUSIONS

We successfully applied the new classification of chronic pain in ICD-11 on the basis of ICD-10 medical diagnoses and symptom self-report. Participants with CPP differed significantly from participants with CSP on baseline characteristics, self-reported health measures and total health expenditure. The CPSMP was not effective in any of the groups.

SIGNIFICANCE

The current study applies the proposed new classification of chronic pain in ICD-11 and shares the experiences of the diagnostic rating procedure of individuals with chronic pain. Furthermore, it evaluates the effect of the Stanford Self-Management Program.

The relationship between the reporting of euphoria events and early treatment responses to pregabalin: an exploratory post-hoc analysis

Background

Euphoria is a complex, multifactorial problem that is reported as an adverse event in clinical trials of analgesics including pregabalin. The relationship between the reporting of euphoria events and pregabalin early treatment responses was examined in this exploratory post-hoc analysis.

Methods

Data were from patients with neuropathic or non-neuropathic chronic pain enrolled in 40 randomized clinical trials, who received pregabalin (75–600 mg/day) or placebo. Reports of treatment-emergent euphoria events were based on the Medical Dictionary of Regulatory Activities preferred term “euphoric mood”. Prevalence rates of euphoria events overall and by indication were assessed. Post-treatment endpoints included ≥30% improvements in pain and sleep scores up to 3 weeks as well as a ≥1-point improvement in daily pain score up to 11 days after treatment.

Results

13,252 patients were analyzed; 8,501 (64.1%) and 4,751 (35.9%) received pregabalin and placebo, respectively. Overall, 1.7% (n=222) of patients reported euphoria events. Among pregabalin-treated patients, a larger proportion who reported euphoria events achieved an early pain response compared with those who did not report euphoria (30% pain responders in week 1 with euphoria events [43.0%], without euphoria events [24.2%]). Results were similar for weeks 2 and 3. For Days 2–11, a larger proportion of pregabalin-treated patients with (relative to without) euphoria events were 1-point pain responders. Findings were similar in pregabalin-treated patients for sleep endpoints (30% sleep responders in week 1 with euphoria events [50.7%], without euphoria events [36.1%]). Similar results were found for weeks 2 and 3. Patients who received placebo showed similar patterns, although the overall number of them who reported euphoria events was small (n=13).

Conclusion

In patients who received pregabalin for neuropathic or non-neuropathic chronic pain, those who experienced euphoria events may have better early treatment responses than those who did not report euphoria events.

Effect of Baseline Characteristics on the Pain Response to Pregabalin in Fibromyalgia Patients with Comorbid Depression

Objective

To evaluate the effect of baseline characteristics on the treatment response to pregabalin in fibromyalgia (FM) patients with depression.

Design

Post hoc analysis from a randomized, double-blind, placebo-controlled, two-way crossover study of pregabalin (300 or 450 mg/day, twice daily).

Subjects

A total of 193 FM patients taking an antidepressant for comorbid depression.

Methods

The effect of patient baseline characteristics on the treatment response to pregabalin vs placebo was assessed for the primary efficacy end point (mean pain score on an 11-point numeric rating scale). Variables were analyzed using a linear mixed effects model with sequence, period, and treatment as fixed factors, and subject within sequence and within subject error as random factors.

Results

Pregabalin significantly improved mean pain scores vs placebo irrespective of age, duration of FM, number of prior FM medications, depression diagnosis, shorter-term depression (<10 years), prior or no prior opioid use, pain severity, anxiety severity, and sleep disruption severity (all P < 0.05). Compared with placebo, pregabalin did not significantly affect mean pain scores in patients with comorbid insomnia, irritable bowel syndrome, or gastroesophageal reflux disease; severe FM; a diagnosis of depression before FM, longer-term depression (≥ 10 years), more severe depression, or who were taking a high dose of antidepressant.

Conclusions

Pregabalin significantly improved mean pain scores when compared with placebo for the majority of baseline characteristics assessed in FM patients taking an antidepressant for comorbid depression.

The Effectiveness of an Intensive Interdisciplinary Pain Rehabilitation Program in the Treatment of Post-Laminectomy Syndrome in Patients Who Have Failed Spinal Cord Stimulation

Introduction

Post-laminectomy syndrome (PLS) patients who have previously undergone spinal cord stimulation and failed to have significant improvement create a unique challenge for ongoing pain management. We hypothesize that, following successful completion of intensive, interdisciplinary pain rehabilitation (IPR), this patient population can achieve a significant reduction in pain, improvement in mood, functional levels, and self-efficacy.

Materials and methods

A retrospective chart review was conducted comparing the following for patients prior to enrollment in the IPR program and upon completion: numeric rating scale (NRS) pain scores; functional status via the six-minute walk test; mood via the Center for Epidemiologic Studies Depression Scale (CES-D), Multidimensional Pain Inventory (MPI) Life control scores and MPI Interference, and the Pain Catastrophizing Scale (PCS); and self-efficacy via the Pain Self-Efficacy Questionnaire (PSEQ).

Results

Forty-three patients met inclusion criteria, with 17 males and 26 females and a mean age of 64 years. Patients demonstrated a statistically significant increase in six-minute walk test distance of 104 m, a decrease in average NRS pain score of 1.4 points, an increase in average MPI life control by 8.3 points, a decrease average MPI interference by 5.3 points, an increase in average Short Form-36 by 6.5 points, an increase in average PCS by 4.4 points, and an increase in average PSEQ score of 18.1. Their average mood via CES-D improved by 4.2 points.

Conclusions

Intensive, interdisciplinary pain rehabilitation provides an effective therapeutic modality for patients with post-laminectomy syndrome who have failed spinal cord stimulation by decreasing pain levels and by increasing functional status and self-efficacy.

Influence of pregabalin on post-operative pain after laparoscopic cholecystectomy: A meta-analysis of randomised controlled trials

Background:

Pregabalin may have some potential in reducing post-operative pain after laparoscopic cholecystectomy. However, the results remain controversial. We conduct a systematic review and meta-analysis to explore the influence of pregabalin on post-operative pain after laparoscopic cholecystectomy.

Materials and Methods:

PubMed, Embase, Web of science, EBSCO and Cochrane Library databases have been systematically searched. Randomised controlled trials (RCTs) assessing the effect of pregabalin versus placebo on post-operative pain after laparoscopic cholecystectomy are included. The primary outcomes are pain scores at 8–12 h and 20–24 h. Secondary outcomes include sedation score, intraoperative fentanyl requirement, post-operative analgesic requirement, operative duration, post-operative nausea and vomiting, as well as respiratory depression. This meta-analysis is performed using the random-effect model.

Results:

Eight RCTs involving 528 patients were included in the meta-analysis. Overall, compared with control intervention after laparoscopic cholecystectomy, pregabalin treatment is found to significantly reduce pain scores at 20–24 h (Standard Mean difference [Std. MD] = −0.46; 95% confidence interval [CI] = −0.82–−0.10), and post-operative analgesic requirement (Std. MD = −2.64; 95% CI = −3.94–−1.33), but cannot substantially decrease pain scores at 8–12 h (Std. MD = −0.71; 95% CI = −1.70–0.27). In addition, pregabalin results in improved sedation score (Std. MD = 0.92; 95% CI = 0.55–1.29), but has no remarkable influence on intraoperative fentanyl requirement (Std. MD = 0.04; 95% CI = −0.30–0.39), operative duration (Std. MD = 0.34; 95% CI = −0.10–0.77), post-operative nausea and vomiting (Std. MD = 0.79; 95% CI = 0.59–1.11) as well as respiratory depression (Std. MD = 0.71; 95% CI = 0.17–3.02).

Conclusions:

Compared to control intervention after laparoscopic cholecystectomy, pregabalin treatment can significantly decrease pain scores at 20–24 h and post-operative analgesic requirement, with no increase in adverse events.

Psychopharmacology of chronic pain

Chronic pain is a frequent condition that affects an estimated 20% of people worldwide, accounting for 15%-20% of doctors' appointments (Treede et al., 2015). It lacks the acute warning function of physiologic nociception, and instead involves the activation of multiple neurophysiologic mechanisms in the somatosensory system, a complex neuronal network under the control of powerful autoregulatory loops and able to undergo rapid neuroplastic alteration (Verdu et al., 2008). There is a growing body of research suggesting that some such pathways are shared by major psychologic disorders such as depression and anxiety, opening new avenues in co-treatment strategies. In particular, besides anticonvulsants, which are today used as analgesics, other psychopharmaceuticals, such as the tricyclic antidepressants, are displaying efficacy in the treatment of neuropathic and nociceptive chronic pain. The state of the art regarding the mechanisms of nociception and the pharmacology of both the neurotransmitters involved and the wide range of psychoactive compounds that may be useful in the treatment of chronic pain are discussed.

High-Performance Liquid Chromatography Enantioseparations Using Macrocyclic Glycopeptide-Based Chiral Stationary Phases: An Overview

Since their introduction by Daniel W. Armstrong in 1994, antibiotic-based chiral stationary phases have proven their applicability for the chiral resolution of various types of racemates. The unique structure of macrocyclic glycopeptides and their large variety of interactive sites (e.g., hydrophobic pockets, hydroxy, amino and carboxyl groups, halogen atoms, aromatic moieties) are the reasons for their wide-ranging selectivity. The commercially available Chirobiotic™ phases, which display complementary characteristics, are capable of separating a broad variety of enantiomeric compounds with good efficiency, good column loadability, high reproducibility, and long-term stability. These are the major reasons for the frequent use of macrocyclic antibiotic-based stationary phases in HPLC enantioseparations.This overview chapter provides a brief summary of general aspects of antibiotic-based chiral stationary phases including their preparation and their application to direct enantioseparations of various racemates focusing on the literature published since 2004.