A double-blind placebo-controlled trial of milnacipran in the treatment of fibromyalgia

Central amplification and fibromyalgia: disorder of pain processing

Fibromyalgia (FM), a complex chronic pain disorder affecting a heterogeneous patient population, is an area of active basic and clinical research. Although diagnostic criteria for FM have been available for 2 decades, there remains no definitive diagnostic and no consensus regarding its etiology. Accumulating evidence suggests the underlying cause of FM pain results from abnormal pain processing particularly in the central nervous system rather than from dysfunction in peripheral tissues where pain is perceived. In this review, we examine recent studies investigating abnormalities in central pain processing as a component of FM in both preclinical models of generalized muscle hypersensitivity and clinical research in patients with FM. We focus our discussion on two areas where strong evidence exists for abnormalities in sensory signaling: the reduction of descending control, including suppression of descending inhibitory pathways and/or enhancement of descending facilitatory pathways, and changes in key neurotransmitters associated with central sensitization. Finally, we discuss currently available pharmacological treatments indicated for the management of pain in FM patients, based on their proposed mechanism of action and efficacy.

Psychological factors affecting response to antidepressant drugs in fibromyalgia

BACKGROUND

The use of antidepressant drugs in fibromyalgia is extensive despite small evidence of the real impact in the clinical practice setting. This study was aimed to evaluate the long-term efficiency of antidepressant treatment in fibromyalgia and the role of psychosocial factors in treatment response.

METHODS

A total of 102 consecutive patients with fibromyalgia from primary health care centers were studied with psychopathological and psychological assessment interviews and questionnaires. Sustained release venlafaxine was added to previous treatments in flexible doses from 150 to 300 mg daily for a 6-month period. Efficacy measures included the Clinical Global Impression (CGI) scale (patient and clinician versions) and the Fibromyalgia Impact Questionnaire (FIQ) score reduction.

RESULTS

At 6 months, 48% patients were considered responders to treatment (CGI change score 1 or 2) and 23.5% had a mild response. Of note, 57.8% had less fatigue and 31.4% had less pain. The proportion of responders was greater in the group with major depression (65%) than in those without depression (45%), but the difference did not reach statistical significance. However, the reduction of FIQ scores was significantly greater in depressed (21.1; IQR: 1.4-42.0) than in non-depressed patients (41.4; IQR: 23.6-52.6) (P<0.05). FIQ score reduction was significantly smaller in patients taking concomitant opiate treatment (P<0.01) and in patients seeking incapacitation (P<0.01).

CONCLUSION

Antidepressant treatment in fibromyalgia was effective in patients with and without major depression, but the functional response was greater in depressed patients. Treatment response to antidepressants might be significantly influenced by attitudinal and psychosocial factors of the disease.

Early reduction in painful physical symptoms is associated with improvements in long-term depression outcomes in patients treated with duloxetine

BACKGROUND

To investigate the association of the change of painful physical symptoms (PPS) after 4 weeks, with the 6-month treatment outcomes of depressive symptoms in patients treated with duloxetine in clinical practice.

METHODS

Multicenter, prospective, 6-month, non-interventional study in adult outpatients with a depressive episode and starting treatment with duloxetine. Depression severity was assessed by the clinician (Inventory for Depressive Symptomatology [IDS-C]) and patient (Kurz-Skala Stimmung/Aktivierung [KUSTA]). Somatic symptoms and PPS were assessed using the patient-rated Somatic Symptom Inventory (SSI) and visual analog scales (VAS) for pain items. Association of change in PPS with outcomes of depressive symptoms was analyzed based on mean KUSTA scores (mean of items mood, activity, tension/relaxation, sleep) and achievement of a 50% reduction in the total IDS-C score after 6 months using linear and logistic regression models, respectively.

RESULTS

Of the 4,517 patients enrolled (mean age: 52.2 years, 71.8% female), 3,320 patients (73.5%) completed the study. 80% of the patients had moderate to severe overall pain (VAS > 30 mm) at baseline. A 50% VAS overall pain reduction after 4 weeks was associated with a 13.32 points higher mean KUSTA score after 6 months, and a 50% pain reduction after 2 weeks with a 6.33 points improvement. No unexpected safety signals were detected in this naturalistic study.

CONCLUSION

Pain reduction after 2 and 4 weeks can be used to estimate outcomes of long-term treatment with duloxetine. PPS associated with depression have a potential role in predicting remission of depressive symptoms in clinical practice.

Medication dosing patterns associated with duloxetine and pregabalin among patients with fibromyalgia

OBJECTIVE

To examine medication dosing patterns of duloxetine and pregabalin among patients with fibromyalgia.

METHODS

From a large US administrative claims database, commercially insured fibromyalgia patients aged 18-64 who initiated duloxetine or pregabalin in 2006 were selected. Initiation was defined as a 90-day medication gap, with the dispense date of the first initiation as the index date. All patients selected had continuous enrollment over the 12-month pre- and post-index periods, and were classified into the duloxetine or pregabalin cohorts based on their index agent. Initial daily dose, average daily dose over the 12-month post-index period, mean and median daily doses and daily costs of each of the first 12 prescriptions were examined for both the duloxetine and pregabalin cohorts.

RESULTS

Both the duloxetine (n = 3773) and pregabalin (n = 4189) cohorts had a mean age of 50 years (median age: 52 vs. 53). The average initial daily dose was 55.7 mg for duloxetine and 161.5 mg for pregabalin. Over the 12-month post-index period, the average daily dose per patient was 55.6 mg for duloxetine and 195.7 mg for pregabalin. The average daily doses for the first 12 duloxetine prescriptions ranged 55.7-60.3 mg, with the mean daily costs between $3.77 and $4.59. For the first 12 pregabalin prescriptions, the average daily dose increased from 161.5 mg to 282.4 mg, while the average daily costs ranged between $4.30-4.61.

CONCLUSIONS

Among patients with fibromyalgia, duloxetine and pregabalin initiators had different dosing patterns. The average daily dose for duloxetine was relatively stable over time, while pregabalin patients had significant dose increase over the 12-month post-index period.

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.

Fibromyalgia: from pathophysiology to therapy

Individuals with fibromyalgia generally experience chronic widespread pain, which can be accompanied by further symptoms including fatigue, sleep disturbances, cognitive dysfunction, anxiety and depressive episodes. As the recognition and diagnosis of fibromyalgia has improved, the availability of therapeutic options for patients has increased. Furthermore, research into the neurobiological mechanisms that contribute to the chronic pain and concomitant symptoms experienced by patients with fibromyalgia has advanced our understanding of this debilitating disorder. In this Review, we aim to provide an overview of existing pathophysiological concepts. The roles of biological and psychological stress, genetic factors, and pain and sensory processing in the pathophysiology of fibromyalgia and related conditions are discussed. In addition, pharmacological treatments, including monoamine modulators, calcium channel modulators and γ-aminobutyric acid modulators, as well as nonpharmacological treatment options are considered.

Pharmacotherapy for fibromyalgia

Fibromyalgia (FM) is a chronic disorder characterized by multifocal pain and other associated somatic symptoms including fatigue, insomnia, cognitive/memory problems, and even psychological distress. It appears that 2–4% of the general population suffers from FM. FM negatively impacts the physical functioning of its patients, as evidenced by difficulties with multiple daily activities, as well as affecting emotional health, social functioning, and health related quality of life. This review will discuss the potential theories that possibly contribute to the pathogenesis of FM, although the precise mechanism is unknown. The evolution of the assessment of FM will also be examined, with the waning use of tender point examinations and the appearance of new simple, practical diagnostic criteria. Although non-pharmacologic therapeutic options (exercise, education, cognitive–behavioral therapy) have been shown to be extremely effective in FM, the focus of this article will be on pharmacologic strategies. Non-Food and Drug Administration (FDA) approved as well as FDA approved agents will be presented. Each agent's therapeutic “niche” in FM management will be discussed based on its pharmacologic profile, patient responsiveness, and tolerability. Finally a clinical algorithm will be presented for the step-wise management of pain and other associated symptoms of FM.

Functional somatic complaints in depression: An overview

Depression is a disorder of major public health importance which often manifests through functional somatic complaints. Concept of functional somatic complaints dates back to the time of Wernicke and is later substantiated by various authors. Although considered as an alternative 'idiom of distress' in certain culture, functional somatic complaints are universal. Various international, cross-cultural, inpatient and outpatient based studies have reported that about two-third of subjects of depression present to clinicians with functional somatic complaints which often leads to misrecognition of their illness and in turn leads to increased utilization of health services. These functional somatic complaints can be related to various organ systems but show remarkable homogeneity in their presentation across culture. Various instruments have attempted to tap the functional somatic complaints but are limited by their cross-cultural validity. Among important correlates of functional somatic complaints are female gender, severity of depression, subsyndromal anxiety, alexithymia, somatosensory amplification and hypochondriacal worry are to name a few. Neurobiological understanding implicates neurotransmitters serotonin and norepinephrine, resultantly Serotonin Norepinephrine Reuptake Inhibitors have been found to be effective in treating functional somatic complaints in depression. Future revisions in the nosological systems should consider giving proper importance to some of these symptoms for diagnosing depression.

The FIBRO System: A Rapid Strategy for Assessment and Management of Fibromyalgia Syndrome

Fibromyalgia syndrome (FMS) is a complex disorder of widespread pain and tenderness associated with numerous other symptoms including fatigue, cognitive dysfunction, nonrestorative sleep, depression, anxiety, and stiffness. While new diagnostic criteria and previous management guidelines require quantitation of the severity of associated FMS symptoms experienced by individual patients, no system for rapid patient assessment has been made available to provide a basis for diagnosis, treatment selection and follow-up for clinicians in busy practices who have limited time. This review presents the FIBRO System, an easily remembered system for FMS symptom quantitation using the FIBRO mnemonic along with verbal questions on simple 0-10 scales to assess symptom severity (the FIBRO Problem Scale) and response to treatment (the FIBRO Change Scale) along with recommendations for pharmacologic and nonpharmacologic therapies to address individual FIBRO symptoms. This symptom-based approach can improve the care of FMS patients by providing a comprehensive, focused assessment in limited time.

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

Fibromyalgia (FM) is a chronic widespread pain condition that is estimated to affect 5 million US adults. Several molecular pathophysiologies are thought to contribute to the symptoms of FM, complicating the development of effective clinical management techniques. It is now known that abnormalities in both nociceptive and central pain processing systems are necessary (but perhaps not sufficient) to condition the onset and maintenance of FM, producing associated neuropsychologic symptoms such as pronounced fatigue, sleep abnormalities, cognitive difficulties, stress sensitivity, anxiety, and depression. Current treatment strategies are focused primarily on correcting the pathophysiologic mechanisms underlying these nervous system abnormalities. Clinical studies demonstrate the safety and efficacy of three drugs recently approved for the treatment of FM: pregabalin (an alpha-2-delta ligand), and duloxetine and milnacipran (serotonin/norepinephrine reuptake inhibitors). This review describes these pharmaceuticals in detail and discusses their current roles in FM management.

Effectiveness of milnacipran for the treatment of chronic pain in the orofacial region

OBJECTIVES

The effect of milnacipran for the treatment of chronic pain in the orofacial region, including burning mouth syndrome (BMS) and atypical odontalgia (AO), was assessed while accounting for the influence of concurrent depressive symptoms on the pain-relieving effect.

METHODS

Milnacipran was administered for 12 weeks to 36 patients with chronic pain in the orofacial region (3 men and 29 women, aged between 22 and 76 years with a mean age of 59 years). Of those patients, 22 and 10 patients had BMS and AO, respectively. The initial dose of milnacipran was 15 mg a day, and the dose was raised up to 100 mg a day. Pain was assessed using the visual analog scale, and symptoms of depression were evaluated using the Hamilton Depression Rating Scale at baseline and at weeks 1, 2, 4, 6, 8, 10, and 12 of the study treatment.

RESULTS

Data from 32 patients who completed the study were included in the analysis. The visual analog scale score significantly decreased after the 12-week treatment, and it showed a similar time course of decline irrespective of concurrent depressive symptoms during the 12 weeks.

CONCLUSIONS

Treatment with milnacipran resulted in a significant improvement of chronic pain in the orofacial region irrespective of concurrent symptoms of depression. The present results suggested that milnacipran may be an effective agent for treatment of such disorders.

Fibromyalgia syndrome: a discussion of the syndrome and pharmacotherapy

Fibromyalgia is a complex condition that is characterized by chronic widespread pain and multiple other symptoms, including fatigue, sleep disturbances, cognitive dysfunction, stiffness, and depressive episodes. Fibromyalgia may coexist and/or overlap with other conditions that may involve central sensitivity, including chronic fatigue syndrome, irritable bowel syndrome, irritable bladder syndrome or interstitial cystitis, and temporomandibular disorder. The pathophysiology of fibromyalgia remains uncertain but is believed to be partly the result of central systems affecting afferent processing as well as impaired endogenous pain-inhibitory systems. Abnormal central nociceptive processing may contribute to fibromyalgia, producing heightened responses to various noxious stimuli with resulting mechanical hyperalgesia. Fibromyalgia remains a clinical diagnosis. There has been a recent paradigm shift away from requiring 11 or more out of 18 tender points and instead focusing on the presence of chronic widespread pain as well as symptoms of fatigue, unrefreshed sleep, and other somatic complaints. Although there is no known cure for fibromyalgia, multidisciplinary team efforts using combined treatment approaches, including patient education, aerobic exercise, cognitive behavioral therapy, and pharmacologic therapies (serotonin norepinephrine reuptake inhibitors [eg, duloxetine, milnacipran] and alpha 2-delta receptor ligands [eg, pregabalin]) may improve symptoms as well as function of patients with fibromyalgia.

Pharmacological treatment of fibromyalgia syndrome: new developments

Fibromyalgia is a chronic pain disorder characterized by widespread pain, stiffness, insomnia, fatigue and distress. Several randomized controlled trials (RCTs) have shown moderate effectiveness of pharmacological therapies for fibromyalgia pain. Evidence from these trials suggests that pharmacological therapy can not only improve pain but also fatigue, function and well-being in patients with fibromyalgia. Duloxetine and milnacipran, two highly selective serotonin-norepinephrine (noradrenaline) reuptake inhibitors, and the alpha(2)delta agonist pregabalin have been approved by the US FDA for the treatment of fibromyalgia symptoms. In general, about half of all treated patients seem to experience a 30% reduction of symptoms, suggesting that many patients with fibromyalgia will require additional therapies. Thus, other forms of treatment, including exercise, cognitive behavioural therapies and self-management strategies, may be necessary to achieve satisfactory treatment outcomes. Despite promising results of pilot trials, RCTs with dopamine receptor agonists and sodium channel antagonists have so far been disappointing for patients with fibromyalgia. However, new pharmacological approaches for the treatment of fibromyalgia pain and insomnia using sodium oxybate appear to be promising.

Milnacipran for the management of fibromyalgia syndrome

Fibromyalgia syndrome (FMS) is a widespread pain condition associated with fatigue, cognitive dysfunction, sleep disturbance, depression, anxiety, and stiffness. Milnacipran is one of three medications currently approved by the Food and Drug Administration in the United States for the management of adult FMS patients. This review is the second in a three-part series reviewing each of the approved FMS drugs and serves as a primer on the use of milnacipran in FMS treatment including information on pharmacology, pharmacokinetics, safety and tolerability. Milnacipran is a mixed serotonin and norepinephrine reuptake inhibitor thought to improve FMS symptoms by increasing neurotransmitter levels in descending central nervous system inhibitory pathways. Milnacipran has proven efficacy in managing global FMS symptoms and pain as well as improving symptoms of fatigue and cognitive dysfunction without affecting sleep. Due to its antidepressant activity, milnacipran can also be beneficial to FMS patients with coexisting depression. However, side effects can limit milnacipran tolerability in FMS patients due to its association with headache, nausea, tachycardia, hyper- and hypotension, and increased risk for bleeding and suicidality in at-risk patients. Tolerability can be maximized by starting at low dose and slowly up-titrating if needed. As with all medications used in FMS management, milnacipran works best when used as part of an individualized treatment regimen that includes resistance and aerobic exercise, patient education and behavioral therapies.

Milnacipran: beyond a role of antidepressant

Milnacipran is a serotonin and norepinephrine reuptake inhibitor (SNRI) with negligible effects on any presynaptic or postsynaptic receptors. Milnacipran has unique pharmacokinetic and pharmacodynamic characteristics that distinguish it from the other marketed serotonin and norepinephrine reuptake inhibitors, venlafaxine, desvenlafaxine, and duloxetine such as equipotent serotonin and norepinephrine reuptake inhibition and a linear dose-concentration trend at therapeutic doses. The half-life of milnacipran is approximately 8 hours. In addition, milnacipran does not inhibit the cytochrome P 450 system, indicating minimal propensity for drug-drug interactions. The antidepressant efficacy of milnacipran has been clearly established in a number of randomized, double-blind, placebo-controlled clinical trials, and it has been widely used for treating major depressive disorder. Moreover, evidence suggests that milnacipran is effective and tolerable in the treatment of fibromyalgia and may have usefulness for fatigue and anxiety symptoms. The current paper reviews researches conducted to date that is relevant to the efficacy, tolerability, and mechanism of action of milnacipran in the treatment of depression, fibromyalgia, and other psychiatric syndromes. Future directions of research are also identified.

Desvenlafaxine succinate: a newer antidepressant for the treatment of depression and somatic symptoms

Desvenlafaxine succinate (DVS) is one of several serotonin-norepinephrine reuptake inhibitors (SNRIs). Others are venlafaxine hydrochloride, milnacipran, and duloxetine. Desvenlafaxine has been approved by the US Food and Drug Administration (FDA) for the treatment of major depressive disorder (MDD) based on a number of randomized, placebo-controlled clinical trials. Clinical studies have investigated the efficacy of DVS in doses ranging from 50 to 400 mg/day for the treatment of MDD in adult outpatients. The effects of DVS 50 mg/day have been clearly distinguished from placebo in the reduction of MDD symptoms in such clinical trials. No additional therapeutic benefits were found at doses > 50 mg/day. The recommended dose of DVS ranges from 50 to 100 mg. Desvenlafaxine is currently the third SNRI approved by the FDA for this indication. Preliminary evidence also suggests the clinical usefulness of DVS in the treatment of vasomotor symptoms of menopause, anxiety symptoms, and painful physical symptoms. The modified pharmacokinetic and pharmacodynamic profiles of DVS differentiate this drug from the original product, venlafaxine. Significant points of difference, compared with venlafaxine, are once-daily dosing and the achievement of steady-state plasma concentrations within 4 to 5 days. To summarize, current evidence indicates that DVS has proven efficacy, acceptable safety and tolerability profiles, convenient dosing, and minimal impact on the cytochrome P450 enzyme system. A reduced risk for pharmacokinetic drug interactions is a potential advantage over other selective serotonin noradrenaline reuptake inhibitors. Desvenlafaxine succinate has demonstrated its efficacy for treating MDD but its variable efficacy, as shown in individual studies, limited long-term data, and its different risk-to-benefit ratio compared with earlier antidepressants, means that further investigation of this drug is necessary.

Duloxetine: a review of its safety and efficacy in the management of fibromyalgia syndrome

Fibromyalgia (FM) is a chronic disorder characterized by widespread pain and other associated symptoms including fatigue, insomnia, cognitive/memory problems, and even psychological distress. Duloxetine is one of three FDA approved medications (the other two being milnacipran and pregabalin) for the treatment of FM. It has been demonstrated that FM patients possess low central nervous system levels of serotonin and norepinephrine. Duloxetine, which is classified pharmacologically as a serotonin-norepinephrine reuptake inhibitor (SNRI), may be beneficial for FM patients by increasing these levels. This review will touch briefly upon the pathophysiology of FM, diagnostic tools, currently available therapeutic options (both pharmacologic and non-pharmacologic), as well as the pharmacokinetic/pharmacodynamic properties of duloxetine. In addition, the efficacy and safety/tolerability of duloxetine exclusively in FM will be assessed through examination of 5 randomized controlled trials, as well as pooled analyses of current data. Suggestions for a therapeutic niche for duloxetine in FM are discussed based on a presentation of the characteristics of duloxetine.

Serotonin-norepinephrine reuptake inhibitors for pain control: premise and promise

The precise mechanisms of pain perception and transmission in the central nervous system have not been fully elucidated. However, extensive data support a role for the monoamine neurotransmitters, serotonin and norepinephrine, in the modulation of pain. Experiments with animal models of pain indicate that noradrenergic interventions, and to a lesser extent serotonergic interventions, reduce pain-related behavior. This is supported by data from clinical trials in humans in which antidepressants have been shown to reduce pain and functional impairment in central and neuropathic pain conditions. These effects are particularly well-studied in trials with serotonin-norepinephrine reuptake inhibitors (SNRIs), which have provided a useful tool in the clinician's arsenal, particularly considering the limitations of other classes of pain medications such as opioids, anti-inflammatories, and anticonvulsants (i.e., limited efficacy, safety and tolerability issues). Moreover, painful physical symptoms are frequently comorbid with major psychiatric disorders such as major depressive disorder and anxiety disorders. This paper reviewed and summarized the rationale and potential role of SNRIs for the control of pain including clinical and preclinical background. Currently evidence does not definitely support a role of the SNRIs, while limited data propose a putative promise of SNRIs in the treatment of pain related disorders including fibromyalgia and depressed patients with multiple somatic complaints. More researches are warranted to generalize currently available preliminary evidences.

Elevated insular glutamate in fibromyalgia is associated with experimental pain

OBJECTIVE

Central pain augmentation resulting from enhanced excitatory and/or decreased inhibitory neurotransmission is a proposed mechanism underlying the pathophysiology of functional pain syndromes such as fibromyalgia (FM). Multiple functional magnetic resonance imaging studies implicate the insula as a region of heightened neuronal activity in this condition. Since glutamate (Glu) is a major cortical excitatory neurotransmitter that functions in pain neurotransmission, we undertook this study to test our hypothesis that increased levels of insular Glu would be present in FM patients and that the concentration of this molecule would be correlated with pain report.

METHODS

Nineteen FM patients and 14 age- and sex-matched pain-free controls underwent pressure pain testing and a proton magnetic resonance spectroscopy session in which the right anterior insula and right posterior insula were examined at rest.

RESULTS

Compared with healthy controls, FM patients had significantly higher levels of Glu (mean +/- SD 8.09 +/- 0.72 arbitrary institutional units versus 6.86 +/- 1.29 arbitrary institutional units; P = 0.009) and combined glutamine and Glu (i.e., Glx) (mean +/- SD 12.38 +/- 0.94 arbitrary institutional units versus 10.59 +/- 1.48 arbitrary institutional units; P = 0.001) within the right posterior insula. No significant differences between groups were detected in any of the other major metabolites within this region (P > 0.05 for all comparisons), and no group differences were detected for any metabolite within the right anterior insula (P > 0.11 for all comparisons). Within the right posterior insula, higher levels of Glu and Glx were associated with lower pressure pain thresholds across both groups for medium pain (for Glu, r = -0.43, P = 0.012; for Glx, r = -0.50, P = 0.003).

CONCLUSION

Enhanced glutamatergic neurotransmission resulting from higher concentrations of Glu within the posterior insula may play a role in the pathophysiology of FM and other central pain augmentation syndromes.

Clinical Aspects and Management of Fibromyalgia Syndrome

Fibromyalgia syndrome (FMS) is a chronic and debilitating musculoskeletal pain disorder of unknown aetiology with usual accompanying features of fatigue, sleep disturbances and stiff- ness. Its place in medical textbooks was controversial with rheumatologists holding the helm of its management for many years. Over the last decade, abnormalities have been identified at multiple levels in the peripheral, central, and sympathetic nervous systems as well as the hypothalomo-pitutary-adrenal axis stress response system. With the elucidation of these pathways of pain, FMS is known more as a central sensitivity syndrome. This led to tremendous increment in interest in both pharmacological and non-pharmacological treatment of FMS. The United States Food and Drug Administration (FDA) has also successively approved 3 drugs for the management of fibromyalgia – pregabalin, duloxetine and milnacipran. Non-pharmacological modalities showed aerobic exercise, patient education and cognitive behavioural therapy to be most effective. Overall, management of FMS requires a multi-disciplinary approach. Key words: Aetiology, Fibromyalgia-Fibromyositis Syndromes, History, Pain syndrome

Predictors of premature discontinuation of treatment in multiple disease states

BACKGROUND

Premature discontinuation of treatment impacts outcomes of clinical practice. The traditional perception has been patient discontinuation is mainly driven by unwanted side effects. Systematic analysis of data from clinical trials across several disease states was performed to identify predictors of premature discontinuation during clinical interventions.

METHODS

A post hoc analysis was conducted on 22 randomized, double-blind, placebo-controlled clinical trials for treatment of fibromyalgia, diabetic peripheral neuropathic pain, major depressive disorder, and generalized anxiety disorder. Analyses were conducted on pooled data within each disease state.

RESULTS

Lack of early therapeutic response was a significant predictor of patient discontinuation in each disease state. Visit-wise changes in therapeutic response and severity of adverse events were also significant risk factors, with change in therapeutic response having a higher significance level in three disease states. Patients who discontinued due to adverse events had similar therapeutic responses as patients completing treatment.

CONCLUSION

Contrary to the conventional belief that premature treatment discontinuation is primarily related to adverse events, our findings suggest lack of therapeutic response also plays a significant role in patient attrition. This research highlights the importance of systematic monitoring of therapeutic response in clinical practice as a measure to prevent patients' discontinuation from pharmacological treatments.

Neurophysiopathogenesis of fibromyalgia syndrome: a unified hypothesis

The characteristic presenting complaint of patients with fibromyalgia syndrome (FMS) is chronic widespread allodynia. Research findings support the view that FMS is an understandable and treatable neuropathophysiologic disorder. The pain of FMS is often accompanied by one or more other manifestations, such as affective moods, cognitive insecurity, autonomic dysfunction, or irritable bowel or bladder. Growing evidence suggests that this is a familial disorder with many underlying genetic associations. New findings from brain imaging and polysomnography imply that FMS may be a disorder of premature neurologic aging. A conceptual model at the molecular level is proposed to explain many of the observed features of FMS. The model can also explain anticipated responses to FDA approved pharmacologic therapies.

Desvenlafaxine: a new antidepressant or just another one?

Desvenlafaxine (DVS) is a serotonin-norepinephrine reuptake inhibitor (SNRI) with a different pharmacokinetic and pharmacodynamic profile to venlafaxine. It was approved in February 2008 by the United States Food and Drug Administration for the treatment of major depressive disorder (MDD) based on a number of randomized, placebo-controlled clinical trials demonstrating efficacy and safety for patients with MDD. Current evidence indicates that DVS has proven efficacy, acceptable safety and tolerability profiles, convenient once-daily dosing and minimal impact on cytochrome P450 enzyme system and adverse event-prone neuroreceptors. As with all monoamine-based antidepressants, DVS has mixed efficacy results from individual studies, unestablished dosing strategies and limited long-term data, and comparative efficacy/safety with other existing antidepressants should be further investigated. Preliminary evidence also suggests the clinical usefulness of DVS in the treatment of vasomotor symptoms of menopause, anxiety symptoms and painful physical symptoms, although only MDD is the approved indication.

History of depressive and/or anxiety disorders as a predictor of treatment response: a post hoc analysis of a 12-week, randomized, double-blind, placebo-controlled trial of paroxetine controlled release in patients with fibromyalgia

BACKGROUND

Despite of a high comorbidity of depressive and/or anxiety disorders with fibromyalgia, information on the clinical implications of this comorbidity is limited but antidepressants are commonly prescribed to treat fibromyalgia in clinical practice. We investigated whether a history of depressive and/or anxiety disorders was associated with response to paroxetine controlled release (CR) in the treatment of fibromyalgia.

METHODS

One hundred sixteen (116) fibromyalgia subjects were randomized to receive paroxetine CR or placebo for 12 weeks. The primary outcome was treatment response defined as >or=25% reduction in the Fibromyalgia Impact Questionnaire (FIQ) score. In multivariate logistic regression, we determined if a history of depression and/or anxiety disorders was an independent predictor of response to paroxetine CR.

RESULTS

In logistic regression, the history of depression and/or anxiety did not predict treatment response as measured by >or=25% reduction in Fibromyalgia Impact Questionnaire (FIQ) score (OR=0.66, 95% CI=.29-1.49, Wald=0.97, p=0.32), while the drug status (paroxetine CR) was significantly associated with treatment response (OR=2.57, CI=1.2-5.61, Wald=5.5, p=0.02).

CONCLUSION

A significant proportion of patients with fibromyalgia had a history of anxiety and or depressive disorders. However response to treatment of fibromyalgia symptoms with paroxetine CR was not associated with a history of depressive and/or anxiety disorders. Our findings need to be confirmed in more adequately-powered and well-designed subsequent studies.

[Pharmacologic treatment of fibromyalgia: Towards chemical neuromodulation]

Fibromyalgia is a chronic pathology and its main symptom is pain which usually does not respond to traditional analgesia. Its clinical characteristics and the diverse neurophysiologic findings in these patients point to a central sensitization process of the nociceptive system as the central physiopathologic axis in this disease. The knowledge of the nociceptive system functioning and its behavior in this disease has led, in the past few years, to new possibilities for the therapeutic approach. In that way, drugs with a differential mechanism of action, allowing a modulation of the nociceptive system capable of producing analgesia where other medications have failed are being developed. Different drugs with the capacity increasing the activity of biologically active amines implicated in the nociceptive inhibition process and others which are destined to reduce the excitability of the system through ion channels, are being tested with some benefit in Fibromyalgia patients and may constitute a more rational neuromodulating drug profile for this disease. This article reviews the different pharmacological strategies supported by scientific evidence and points to some future research lines that fortifies the therapeutic change taking place in the treatment approach of these patients.

Understanding fibromyalgia: lessons from the broader pain research community

Fibromyalgia (FM) is a chronic pain condition marked by centrally mediated augmentation of pain and sensory processes. Skepticism has marked the history of this condition, but more recent study has identified neurobiological underpinnings supporting many of the symptoms associated with this condition. Early research in FM had unprecedented latitude within the rheumatology community to borrow heavily from theory and methods being applied in chronic pain research more generally. These insights facilitated rapid advances in FM research, not the least of which was the abandonment of a peripheral focus in favor of studying central mechanisms associated with central augmentation. Currently, rapid-paced discovery is taking place in FM genetics, patient assessment, new therapeutic targets, and novel methods of treatment delivery. Such insights are not likely to be limited in application just to FM and could have relevance to the broader field of pain research as well.

PERSPECTIVE

This manuscript reviews the history of FM and its diagnosis, evidence supporting central augmentation of pain in FM, potential mechanisms of central augmentation, current approaches to integrated care of FM, and areas of active collaboration between FM research and other chronic pain conditions.

Milnacipran

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The Efficacy and Safety of Milnacipran for Treatment of Fibromyalgia. A Randomized, Double-blind, Placebo-controlled Trial

Objective.

To evaluate the safety and efficacy of milnacipran, a dual norepinephrine and serotonin reuptake inhibitor, in the treatment of fibromyalgia (FM).

Methods.

A 27-week, randomized, double-blind, multicenter study compared milnacipran 100 and 200 mg/day with placebo in the treatment of 888 patients with FM. Two composite responder definitions were used to classify each patient’s individual response to therapy. “FM responders” concurrently satisfied response criteria for improvements in pain (visual analog scale 24-h morning recall), patient global impression of change (PGIC), and physical functioning (SF-36 Physical Component Summary); while “FM pain responders” concurrently satisfied response criteria for improvements in pain and PGIC.

Results.

At the primary endpoint, after 3-month stable dose treatment, a significantly higher percentage of milnacipran-treated patients met criteria as FM responders versus placebo (milnacipran 200 mg/day, p = 0.017; milnacipran 100 mg/day, p = 0.028). A significantly higher percentage of patients treated with milnacipran 200 mg/day also met criteria as FM pain responders versus placebo (p = 0.032). Significant pain reductions were observed after Week 1 with both milnacipran doses. At 15 weeks, milnacipran 200 mg/day led to significant improvements over placebo in pain (realtime, daily and weekly recall; all measures, p < 0.05), PGIC (p < 0.001), fatigue (p = 0.016), cognition (p = 0.025), and multiple SF-36 domains. Milnacipran was safe and well tolerated by the majority of patients during 27 weeks of treatment; nausea and headache were the most common adverse events.

Conclusion.

Milnacipran is safe and effective for the treatment of multiple symptoms of FM.

Treatment options and patient perspectives in the management of fibromyalgia: future trends

Fibromyalgia (FM) is a common, complex, and difficult to treat chronic widespread pain disorder, which usually requires a multidisciplinary approach using both pharmacological and non-pharmacological (education and exercise) interventions. It is a condition of heightened generalized sensitization to sensory input presenting as a complex of symptoms including pain, sleep dysfunction, and fatigue, where the pathophysiology could include dysfunction of the central nervous system pain modulatory systems, dysfunction of the neuroendocrine system, and dysautonomia. A cyclic model of the pathophysiological processes is compatible with the interrelationship of primary symptoms and the array of postulated triggers associated with FM. Many of the molecular targets of current and emerging drugs used to treat FM have been focused to the management of discrete symptoms rather than the condition. Recently, drugs (eg, pregabalin, duloxetine, milnacipran, sodium oxybate) have been identified that demonstrate a multidimensional efficacy in this condition. Although the complexity of FM suggests that monotherapy, non-pharmacological or pharmacological, will not adequately address the condition, the outcomes from recent clinical trials are providing important clues for treatment guidelines, improved diagnosis, and condition-focused therapies.

[Pharmacological treatment of fibromyalgia syndrome]

BACKGROUND

An interdisciplinary guideline for the treatment of fibromyalgia syndrome (FMS) and chronic widespread pain (CWP) was developed in cooperation with ten German medical and psychological associations and two patients' self-help organizations.

METHODS

Using the Cochrane Collaboration Reviews (1993-12/2006), Medline (1980-2006), PsychInfo (1966-12/2006), and Scopus (1980-12/ 2006) a systematic literature search was performed, which included all randomised controlled trials (RCT) evaluating multicomponent therapy in FMS and CWP. Levels of evidence were assigned according to the classification system of the Oxford Centre for Evidence-Based Medicine. The strength of recommendation was graded according to the German program for disease management guidelines. Consensus was achieved using a multi-step nominal group procedure.

RESULTS

The short-term use of amitriptyline is strongly recommended (grade A) and the short-term use of fluoxetine und duloxetine is recommended (grade B).

CONCLUSIONS

The recommendations regarding pharmacological treatment of FMS are limited by the short duration of the RCT, the lack of follow-ups and absence of cost-effectiveness studies.

The relationship between fibromyalgia and major depressive disorder: a comprehensive review

OBJECTIVE

A large body of evidence suggests that the relationship between major depressive disorder (MDD) and fibromyalgia (FM) is complex. Improved understanding of this relationship promises to provide clinicians with better assessment and treatment options for both disorders.

METHOD

This paper reviews research on the prevalence, etiology and pathogenesis, clinical characterization, and treatment of FM and MDD, as well as studies that examined the relationship between these disorders. Studies were identified via PubMed literature search.

RESULTS

Our findings point to substantial similarities in neuroendocrine abnormalities, psychological characteristics, physical symptoms and treatments between FM and MDD. However, currently available findings do not support the assumption that MDD and FM refer to the same underlying construct or can be seen as subsidiaries of one disease concept.

CONCLUSION

New methodological and theoretical approaches may lead to a better understanding of the link between FM and MDD, and to more effective psychological and psychopharmacological therapies for FM patients. In the meantime, clinicians should carefully screen for a history of MDD in patients with FM.