New and emerging therapeutic agents for the treatment of fibromyalgia: an update

The effect of duloxetine on postoperative pain and opium consumption in spine surgery: A systematic review

Background

Postoperative pain after spinal surgery is a major problem that can impact patients' quality of life. Duloxetine is a serotonin and norepinephrine reuptake inhibitor (SNRI) with analgesic effect in different pain disorders. In this study, we aim to evaluate the safety and analgesic effect of duloxetine on acute and chronic pain following spine surgery.

Methods

A systematic search was completed on MEDLINE, PsycINFO, and Embase through OVID from inception to April 2023 to find relevant articles. We used Cochrane methodology to evaluate the bias of included studies. Investigated outcomes included postoperative pain, opioid consumption, and adverse events.

Results

Seven articles involving 487 participants were included in our systematic review. Out of 7 papers, 5 were randomized clinical trials, 1 was a pilot trial and 1 was a retrospective observational study. The results of these studies indicated the analgesic effect of duloxetine on postoperative pain, which was measured using numeric rating scale, verbal numeric scale, brief pain inventory, and visual analogue scale. Duloxetine was generally safe without serious adverse events. The most common reported adverse events included headache, nausea, vomiting, itching, dizziness, and drowsiness.

Conclusions

Duloxetine may be an effective treatment option for postoperative pain following spine surgery, but further rigorously designed and well-controlled randomized trials are required.

Efficacy of duloxetine compared with opioid for postoperative pain control following total knee arthroplasty

Background

The purpose of this study was to assess the efficacy of duloxetine as an alternative to opioid treatment for postoperative pain management following total knee arthroplasty (TKA).

Methods

Among 944 patients, 290 (30.7%) of patients received opioid or duloxetine for pain control for 6 weeks when the pain Visual Analogue Scale (VAS) score was greater than 4 out of 10 at the time of discharge. 121 patients in the Opioid group and 118 in the Duloxetine group were followed up for more than one year. Preoperative and postoperative patient reported outcome measures (pain VAS score, Western Ontario and McMaster Universities OA Index (WOMAC) score were compared. The rate of further drug prescription (opioid or duloxetine) after 6 weeks of first prescription, 30-day readmission rate, and side effects were also investigated.

Results

There was no significant difference in pain VAS score, WOMAC Pain and Function score, at each time point between before and after surgery (all p>0.05). Fifteen (9.8%) patients in the opioid group and six (4.4%) patients in the duloxetine group were prescribed additional medication after first 6 weeks, showing no significant (p>0.05) difference in proportion. The 30-day readmission rate and the incidence of side effects were also similar (all p>0.05). There was no difference in the incidence of side effects between the two groups (p>0.05).

Conclusion

Duloxetine and opioid did not show any difference in pain control, function, and side effects for up to one year after TKA. Although large-scale randomized controlled trials are still required to further confirm the side effects of duloxetine, it can be considered as an alternative to opioid for postoperative pain control following TKA.

You get used to it, or do you: symptom length predicts less fibromyalgia physical impairment, but only for those with above-average self-efficacy

To determine whether the effects of symptom duration on fibromyalgia physical impairment are moderated by symptom self-efficacy, data from 572 female participants, who were members of a large health maintenance organization and had a diagnosis of fibromyalgia syndrome (FMS) were assessed. Age, symptom duration, history of physical, sexual, and emotional abuse, fibromyalgia-specific self-efficacy (Arthritis Self-Efficacy Scale adapted for FMS [ASES]), depression (Centers for Epidemiological Studies Depression Scale [CES-D]), fibromyalgia physical impairment (Fibromyalgia Impact Questionnaire [FIQ]), and pain (McGill Present Pain Index [PPI]) were measured five times across 18 months. Linear regressions were performed to predict baseline FIQ and PPI cross-sectionally. Of primary interest was a hypothesized interaction between ASES and symptom duration, which was significant in relation to FIQ but not PPI. Multilevel mixed models were performed to determine whether the same pattern existed longitudinally controlling for baseline symptom duration as an effect of time and ASES. The interaction was significant in the models for both FIQ and PPI. These results suggest that the effects of age and symptom duration on FMS are unique, and that self-efficacy plays a crucial role in moderating disease course (measured by symptom duration or time) in FMS.

Perioperative Duloxetine and Etoricoxibto improve postoperative pain after lumbar Laminectomy: a randomized, double-blind, controlled study

BACKGROUND

Duloxetine, Etoricoxib and opioid are of the commonly administered drugs in Lumbar laminectomy. The aim of this study is to assess the effect of perioperative use of Duloxetine in combination with Etoricoxib on postoperative pain and opioid requirements.

METHODS

One hundred twenty patients with ASA physical status were enrolled with age between 18 and 70 years. Patients were divided randomly into four groups of 30 patients: group P received placebo, group E received etoricoxib 120 mg, group D received duloxetine 60 mg and group D/E received duloxetine 60 mg capsules and etoricoxib 120 mg; 1 h before surgery and 24 h after.

RESULTS

Neither Duloxetine nor etoricoxib individually had effect on pain with movement, while their combination revealed a significant reduction in pain scores over the entire postoperative period at rest and on movement. Etoricoxib showed a significant decrease in pain at all times at rest when compared with group P, while it showed significant pain decrease only at 0, 2 and 4 h when compared with group D. On the other hand duloxetine alone showed significant decrease in pain at rest at 24 h and 48 h when compared with group P. ConcerningMorphine requirement after 24 h.; it wassignificantly lower in the D/E group in comparison with groups P, E and D. It should be noted also that there was a significant decrease morphine requirement in both groups E and D.

CONCLUSION

The perioperative administration of the combination of etoricoxib and duloxetine improved analgesia and reduced opioid consumption without significant side effects.

TRIAL REGISTRATION

ISRCTN48329522 . 17 June 2017.

Milnacipran for pain in fibromyalgia in adults

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 3, 2012. That review considered both fibromyalgia and neuropathic pain, but the efficacy of milnacipran for neuropathic pain is now dealt with in a separate review.Milnacipran is a serotonin-norepinephrine (noradrenaline) reuptake inhibitor (SNRI) that is licensed for the treatment of fibromyalgia in some countries, including Canada, Russia, and the United States.

OBJECTIVES

To assess the analgesic efficacy of milnacipran for pain in fibromyalgia in adults and the adverse events associated with its use in clinical trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE to 18 May 2015, together with reference lists of retrieved papers and reviews, and two clinical trial registries. For the earlier review, we also contacted the manufacturer.

SELECTION CRITERIA

We included randomised, double-blind studies of eight weeks' duration or longer, comparing milnacipran with placebo or another active treatment in fibromyalgia in adults.

DATA COLLECTION AND ANALYSIS

We extracted efficacy and adverse event data, and two review authors examined issues of study quality independently.

MAIN RESULTS

We identified one new study with 100 participants for the pooled analysis. We identified two additional reports of a study using an enriched enrolment randomised withdrawal (EERW) design that included participants from earlier randomised controlled trials and an open-label study. Because this study used the same participants already included in our main analysis, and a different design, we dealt with it separately.The main analysis included six studies (five from the earlier review; 4238 participants in total), all of which were placebo-controlled, and used titration to a target dose of milnacipran 100 or 200 mg, with assessment after 8 to 24 weeks of stable treatment. There were no studies with active comparators. Study quality was generally good, although the imputation method used in analyses of the primary outcomes could overestimate treatment effect.Both doses of milnacipran provided moderate levels of pain relief (at least 30% pain intensity reduction) to about 40% of participants treated, compared to 30% with placebo, giving a number needed to treat for an additional beneficial outcome (NNT) of 6 to 10 (high quality evidence). Using a stricter definition for responder and a more conservative method of analysis gave lower levels of response (while maintaining a 10% difference between milnacipran and placebo) and increased the NNT to 11 (high quality evidence). One EERW study was broadly supportive.Adverse events were common in both milnacipran (86%) and placebo (78%) groups (high quality evidence), but serious adverse events did not differ between groups (less than 2%) (low quality evidence). Nausea, constipation, and headache were the most common events showing the greatest difference between groups (number needed to treat for an additional harmful outcome (NNH) of 5.7 for nausea, 13 for constipation, and 29 for headache) (moderate quality evidence).Withdrawals for any reason were more common with milnacipran than placebo, and more common with 200 mg (NNH 9) than 100 mg (NNH 23), compared with placebo. This was largely driven by adverse event withdrawals, where the NNH compared with placebo was 14 for 100 mg and 7.0 for 200 mg (high quality evidence). Withdrawals due to lack of efficacy were less common with milnacipran than placebo but did not differ between doses (number needed to treat to prevent an additional unwanted outcome (NNTp) of 41) (moderate quality evidence).

AUTHORS' CONCLUSIONS

The evidence available indicates that milnacipran 100 mg or 200 mg is effective for a minority in the treatment of pain due to fibromyalgia, providing moderate levels of pain relief (at least 30%) to about 40% of participants, compared with about 30% with placebo. There were insufficient data to assess substantial levels of pain relief (at least 50%), and the use of last observation carried forward imputation may overestimate drug efficacy. Using stricter criteria for 'responder' and a more conservative method of analysis gave lower response rates (about 26% with milnacipran versus 17% with placebo). Milnacipran was associated with increased adverse events and adverse event withdrawals, which were significantly greater for the higher dose.

Reduction of pain thresholds in fibromyalgia after very low-intensity magnetic stimulation: a double-blinded, randomized placebo-controlled clinical trial

BACKGROUND

Exposure to electromagnetic fields has been reported to have analgesic and antinociceptive effects in several organisms.

OBJECTIVE

To test the effect of very low-intensity transcranial magnetic stimulation on symptoms associated with fibromyalgia syndrome.

METHODS

A double-blinded, placebo-controlled clinical trial was performed in the Sagrado Corazón Hospital, Seville, Spain. Female fibromyalgia patients (22 to 50 years of age) were randomly assigned to either a stimulation group or a sham group. The stimulation group (n=28) was stimulated using 8 Hz pulsed magnetic fields of very low intensity, while the sham group (n=26) underwent the same protocol without stimulation. Pressure pain thresholds before and after stimulation were determined using an algometer during the eight consecutive weekly sessions of the trial. In addition, blood serotonin levels were measured and patients completed questionnaires to monitor symptom evolution.

RESULTS

A repeated-measures ANOVA indicated statistically significant improvement in the stimulation group compared with the control group with respect to somatosensory pain thresholds, ability to perform daily activities, perceived chronic pain and sleep quality. While improvement in pain thresholds was apparent after the first stimulation session, improvement in the other three measures occurred after the sixth week. No significant between-group differences were observed in scores of depression, fatigue, severity of headaches or serotonin levels. No adverse side effects were reported in any of the patients.

CONCLUSIONS

Very low-intensity magnetic stimulation may represent a safe and effective treatment for chronic pain and other symptoms associated with fibromyalgia.

Synergistic effects of celecoxib and bupropion in a model of chronic inflammation-related depression in mice

This study was aimed to characterize the depression-like behaviour in the classical model of chronic inflammation induced by Complete Freund's Adjuvant (CFA). Male Swiss mice received an intraplantar (i.pl.) injection of CFA (50 µl/paw) or vehicle. Behavioural and inflammatory responses were measured at different time-points (1 to 4 weeks), and different pharmacological tools were tested. The brain levels of IL-1β and BDNF, or COX-2 expression were also determined. CFA elicited a time-dependent edema formation and mechanical allodynia, which was accompanied by a significant increase in the immobility time in the tail suspension (TST) or forced-swimming (FST) depression tests. Repeated administration of the antidepressants imipramine (10 mg/kg), fluoxetine (20 mg/kg) and bupropion (30 mg/kg) significantly reversed depression-like behaviour induced by CFA. Predictably, the anti-inflammatory drugs dexamethasone (0.5 mg/kg), indomethacin (10 mg/kg) and celecoxib (30 mg/kg) markedly reduced CFA-induced edema. The oral treatment with the analgesic drugs dipyrone (30 and 300 mg/kg) or pregabalin (30 mg/kg) significantly reversed the mechanical allodyinia induced by CFA. Otherwise, either dipyrone or pregabalin (both 30 mg/kg) did not significantly affect the paw edema or the depressive-like behaviour induced by CFA, whereas the oral treatment with dipyrone (300 mg/kg) was able to reduce the immobility time in TST. Noteworthy, CFA-induced edema was reduced by bupropion (30 mg/kg), and depression behaviour was prevented by celecoxib (30 mg/kg). The co-treatment with bupropion and celecoxib (3 mg/kg each) significantly inhibited both inflammation and depression elicited by CFA. The same combined treatment reduced the brain levels of IL-1β, as well as COX-2 immunopositivity, whilst it failed to affect the reduction of BDNF levels. We provide novel evidence on the relationship between chronic inflammation and depression, suggesting that combination of antidepressant and anti-inflammatory agents bupropion and celecoxib might represent an attractive therapeutic strategy for depression.

Efficacy and safety of mirtazapine in fibromyalgia syndrome patients: a randomized placebo-controlled pilot study

BACKGROUND

Data from an open-label trial suggest that mirtazapine might prove useful in treatment of fibromyalgia syndrome (FMS).

OBJECTIVE

To obtain preliminary efficacy data of mirtazapine for estimation of sample size requirements for a Phase 2 clinical trial in FMS.

METHODS

This 13-week randomized controlled trial compared the effects of mirtazapine 15 mg/day, mirtazapine 30 mg/day, and placebo in 40 patients with FMS. The primary outcomes were change in Pain Visual Analog Scale (PVAS) and proportion of pain responders (≥30% PVAS reduction). Secondary outcomes included scores from the Jenkins Sleep Scale (JSS), Patient Global Impression of Change (PGIC), Fibromyalgia Impact Questionnaire (FIQ), Hamilton Depression Rating Scale (HAM-D), Patient Global Assessment, and self-reported adverse events.

RESULTS

Significant within-group PVAS reductions from baseline were observed in all 3 groups, with the greatest improvement in the mirtazapine 30-mg group (p < 0.005); between-group difference was not significant. The proportion of pain responders did not meet significance criteria (66.67% for mirtazapine 30 mg, 50% for mirtazapine 15 mg, 41.67% for placebo). Significant within-group improvement in JSS scores was seen for mirtazapine 30 mg (p < 0.01) and mirtazapine 15 mg (p < 0.05). Between-group comparison achieved significance for JSS item 3, waking several times per night (p < 0.05). On the PGIC, 72.73% felt better with both mirtazapine dosages compared with 50% for placebo. Within-group FIQ responses indicated improvement in only mirtazapine-treated groups, whereas within-group improvement for HAM-D and Patient Global Assessment was observed in all groups. Based on our findings, the sample size requirement (80% power, 5% type I error) should be 83 per group to detect PVAS change difference between mirtazapine 30 mg and placebo. Common mirtazapine-related adverse events were increased appetite and weight gain.

CONCLUSIONS

Patients with FMS taking mirtazapine exhibited within-group significant improvement in most of the measured outcomes. Between-group analysis was predictably compromised by the small sample size. Mirtazapine was well tolerated. Further study with a larger sample size is likely to be useful.

Patients' and professionals' views on managing fibromyalgia

BACKGROUND

Managing fibromyalgia is a challenge for both health care systems and the professionals caring for these patients, due, in part, to the fact that the etiology of this disease is unknown, its symptoms are not specific and there is no standardized treatment.

OBJECTIVE

The present study examines three aspects of fibromyalgia management, namely diagnostic approach, therapeutic management and the health professional-patient relationship, to explore specific areas of the health care process that professionals and patients may consider unsatisfactory.

METHODS

A qualitative study involving semistructured interviews with 12 fibromyalgia patients and nine health professionals was performed.

RESULTS

The most commonly recurring theme was the dissatisfaction of both patients and professionals with the management process as a whole. Both groups expressed dissatisfaction with the delay in reaching a diagnosis and obtaining effective treatment. Patients reported the need for greater moral support from professionals, whereas the latter often felt frustrated and of little help to patients. Patients and professionals agreed on one point: the uncertainty surrounding the management of fibromyalgia and, especially, its etiology.

CONCLUSION

The present study contributes to a better understanding regarding why current management of fibromyalgia is neither effective nor satisfactory. It also provides insight into how health professionals can support fibromyalgia patients to achieve beneficial results. Health care services should offer greater support for these patients in the form of specific resources such as fibromyalgia clinics and health professionals with increased awareness of the disease.

Milnacipran for neuropathic pain and fibromyalgia in adults

BACKGROUND

Milnacipran is a serotonin-norepinephrine reuptake inhibitor (SNRI) that is sometimes used to treat chronic neuropathic pain and fibromyalgia.

OBJECTIVES

To evaluate the analgesic efficacy and adverse effects of milnacipran in the management of chronic neuropathic pain or fibromyalgia.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and EMBASE to 4th of January 2012, together with reference lists of retrieved papers and reviews.

SELECTION CRITERIA

We included randomised, double-blind studies of eight weeks duration or longer, comparing milnacipran with placebo or another active treatment in chronic neuropathic pain or fibromyalgia.

DATA COLLECTION AND ANALYSIS

We extracted efficacy and adverse event data, and two study authors examined issues of study quality independently.

MAIN RESULTS

Five studies (4138 participants) were included, all of which were placebo-controlled, involved participants with fibromyalgia, and used titration to a target dose of 100 mg or 200 mg milnacipran. There were no other active comparators or studies in other neuropathic pain conditions. Study quality was generally good, although the imputation method used in analyses of the primary outcomes could overestimate treatment effect.Both doses of milnacipran provided moderate levels of pain relief to about 40% of those treated, compared to 30% with placebo, giving a number needed to treat of 8 to 10. Adverse events were common in both milnacipran (87%) and placebo (78%) groups, but serious adverse events (< 2%) did not differ between groups. Nausea and constipation were the most common events showing the greatest difference between groups (number needed to treat for an additional harmful outcome of 7 and 13 respectively, compared with placebo).Withdrawals for any reason were more common with milnacipran than placebo, and more common with 200 mg than 100 mg (NNH of 23 and 8.8 respectively, compared with placebo). This was largely driven by adverse event withdrawals, where the NNH compared with placebo was 14 for 100 mg, and 7.0 for 200 mg). Withdrawals due to lack of efficacy were more common with milnacipran than placebo but did not differ between doses (number needed to treat to prevent an additional unwanted outcome of 45 and 41 respectively).

AUTHORS' CONCLUSIONS

The evidence available indicates that milnacipran 100 mg or 200 mg is effective for a minority in the treatment of pain due to fibromyalgia, providing moderate levels of pain relief (at least 30%) to about 40% of participants, compared with about 30% with placebo. There were insufficient data to assess substantial levels of pain relief (at least 50%), and the use of last observation carried forward imputation may overestimate drug efficacy. Milnacipran is associated with increased adverse events and adverse event withdrawals, which were significantly greater for the higher dose. There were no data for the use of milnacipran for other chronic neuropathic pain conditions.

Cost-effectiveness analysis of pharmacologic treatment of fibromyalgia in Mexico

OBJECTIVE

To identify, from the Mexican Public Health System perspective, which would be the most cost-effective treatment for patients with Fibromyalgia (FM).

MATERIAL AND METHODS

A Markov model including three health states, divided by pain intensity (absence or presence of mild, moderate or severe pain) and considering three-month cycles; costs and effectiveness were estimated for amitriptyline (50mg/day), fluoxetine (80 mg/day), duloxetine (120 mg/day), gabapentin (900 mg/day), pregabalin (450 mg/day), tramadol/acetaminophen (150 mg/1300 mg/día) and amitriptyline/fluoxetine (50mg/80 mg/día) for the treatment of FM. The clinical outcome considered was the annual rate of pain control. Probabilities assigned to the model were collected from published literature. Direct medical costs for FM treatment were retrieved from the 2006 data of the Mexican Institute of Social Security (IMSS) databases and were expressed in 2010 Mexican Pesos. Probabilistic Sensitivity Analyses were conducted.

RESULTS

The best pain control rate was obtained with pregabalin (44.8%), followed by gabapentin (38.1%) and duloxetine (34.2%). The lowest treatment costs was for amitriptyline ($ 9047.01), followed by fluoxetine ($ 10,183.89) and amitriptyline/fluoxetine ($ 10,866.01). By comparing pregabalin vs amitriptyline, additional annual cost per patient for pain control would be around $ 50.000 and $ 75.000 and would result cost-effective in 70% and 80% of all cases.

CONCLUSIONS

Among all treatment options for FM, pregabalin achieved the highest pain control and was cost-effective in 80% of patients of the Mexican Public Health System.

Intersection of chronic pain treatment and opioid analgesic misuse: causes, treatments, and policy strategies

Treating chronic pain in the context of opioid misuse can be very challenging. This paper explores the epidemiology and potential treatments for chronic pain and opioid misuse and identifies educational and regulation changes that may reduce diversion of opioid analgesics. We cover the epidemiology of chronic pain and aberrant opioid behaviors, psychosocial influences on pain, pharmacological treatments, psychological treatments, and social treatments, as well as educational and regulatory efforts being made to reduce the diversion of prescription opioids. There are a number of ongoing challenges in treating chronic pain and opioid misuse, and more research is needed to provide strong, integrated, and empirically validated treatments to reduce opioid misuse in the context of chronic pain.

Listening to Lyrica: contested illnesses and pharmaceutical determinism

Fibromyalgia syndrome is a debilitating pain disorder of unknown origins and a paradigmatic contested illness. As with other contested illnesses, the reality of fibromyalgia is disputed by many physicians. Thus, millions of individuals who are diagnosed with fibromyalgia must cope with chronic symptoms as well as medical and public skepticism. In this context, the U.S. Federal Drug Administration's approval of Lyrica, the first prescription medication specifically for the management of fibromyalgia, is of considerable interest. In this paper I examine the cultural logic whereby the existence (and marketing) of an officially approved prescription medication for a condition lends support to the biomedical existence of the condition itself. I label this logic pharmaceutical determinism and argue that it represents an important new phase in the proliferation of contested illness diagnoses. Using the case of Lyrica, I describe the role that pharmaceutical companies and pharmaceuticals themselves play in promoting and legitimating contested diagnoses and validating those who are so diagnosed. Through a narrative analysis of the Lyrica direct-to-consumer advertising campaign and the responses of fibromyalgia sufferers to the introduction and marketing of Lyrica, I demonstrate the symbiotic relationship between the interests of the pharmaceutical industry, contested illness legitimization, and medicalization. I also provide a gender analysis of this relationship, foregrounding how contested illnesses continue to be shaped by their feminization in a cultural context that equates women with irrationality. Finally, I address the consequences and limitations of relying on the pharmaceutical industry for illness validation.