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

OMERACT-based fibromyalgia symptom subgroups: an exploratory cluster analysis

Introduction

The aim of this study was to identify subsets of patients with fibromyalgia with similar symptom profiles using the Outcome Measures in Rheumatology (OMERACT) core symptom domains.

Methods

Female patients with a diagnosis of fibromyalgia and currently meeting fibromyalgia research survey criteria completed the Brief Pain Inventory, the 30-item Profile of Mood States, the Medical Outcomes Sleep Scale, the Multidimensional Fatigue Inventory, the Multiple Ability Self-Report Questionnaire, the Fibromyalgia Impact Questionnaire–Revised (FIQ-R) and the Short Form-36 between 1 June 2011 and 31 October 2011. Hierarchical agglomerative clustering was used to identify subgroups of patients with similar symptom profiles. To validate the results from this sample, hierarchical agglomerative clustering was repeated in an external sample of female patients with fibromyalgia with similar inclusion criteria.

Results

A total of 581 females with a mean age of 55.1 (range, 20.1 to 90.2) years were included. A four-cluster solution best fit the data, and each clustering variable differed significantly (P <0.0001) among the four clusters. The four clusters divided the sample into severity levels: Cluster 1 reflects the lowest average levels across all symptoms, and cluster 4 reflects the highest average levels. Clusters 2 and 3 capture moderate symptoms levels. Clusters 2 and 3 differed mainly in profiles of anxiety and depression, with Cluster 2 having lower levels of depression and anxiety than Cluster 3, despite higher levels of pain. The results of the cluster analysis of the external sample (n = 478) looked very similar to those found in the original cluster analysis, except for a slight difference in sleep problems. This was despite having patients in the validation sample who were significantly younger (P <0.0001) and had more severe symptoms (higher FIQ-R total scores (P = 0.0004)).

Conclusions

In our study, we incorporated core OMERACT symptom domains, which allowed for clustering based on a comprehensive symptom profile. Although our exploratory cluster solution needs confirmation in a longitudinal study, this approach could provide a rationale to support the study of individualized clinical evaluation and intervention.

Segregating the cerebral mechanisms of antidepressants and placebo in fibromyalgia

Antidepressant drugs are commonly used to treat fibromyalgia, but there is little knowledge about their mechanisms of action. The aim of this study was to compare the cerebral and behavioral response to positive treatment effects of antidepressants or placebo. Ninety-two fibromyalgia patients participated in a 12-week, double-blind, placebo-controlled clinical trial with milnacipran, a serotonin-norepinephrine reuptake inhibitor. Before and after treatment, measures of cerebral pain processing were obtained using functional magnetic resonance imaging. Also, there were stimulus response assessments of pressure pain, measures of weekly pain, and fibromyalgia impact. Following treatment, milnacipran responders exhibited significantly higher activity in the posterior cingulum compared with placebo responders. The mere exposure to milnacipran did not explain our findings because milnacipran responders exhibited increased activity also in comparison to milnacipran nonresponders. Stimulus response assessments revealed specific antihyperalgesic effects in milnacipran responders, which was also correlated with reduced clinical pain and with increased activation of the posterior cingulum. A short history of pain predicted positive treatment response to milnacipran. We report segregated neural mechanisms for positive responses to treatment with milnacipran and placebo, reflected in the posterior cingulum. The increase of pain-evoked activation in the posterior cingulum may reflect a normalization of altered default mode network processing, an alteration implicated in fibromyalgia pathophysiology.

PERSPECTIVE

This study presents neural and psychophysical correlates to positive treatment responses in patients with fibromyalgia, treated with either milnacipran or placebo. The comparison between placebo responders and milnacipran responders may shed light on the specific mechanisms involved in antidepressant treatment of chronic pain.

Once daily controlled-release pregabalin in the treatment of patients with fibromyalgia: a phase III, double-blind, randomized withdrawal, placebo-controlled study

OBJECTIVE

Safety and efficacy of a once daily controlled-released (CR) formulation of pregabalin was evaluated in patients with fibromyalgia using a placebo-controlled, randomized withdrawal design.

RESEARCH DESIGN AND METHODS

This multicenter study included 6 week single-blind pregabalin CR treatment followed by 13 week double-blind treatment with placebo or pregabalin CR. The starting dose of 165 mg/day was escalated during the first 3 weeks, up to 495 mg/day based on efficacy and tolerability. Patients with ≥50% reduction in average daily pain score at the end of the single-blind phase were randomized to continue pregabalin CR at the optimized dose (330-495 mg/day) or to placebo. The primary endpoint was time to loss of therapeutic response (LTR), defined as <30% pain reduction relative to single-blind baseline or discontinuation owing to lack of efficacy or adverse event (AE). Secondary endpoints included measures of pain severity, global assessment, functional status, tiredness/fatigue, and sleep.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT01271933.

RESULTS

A total of 441 patients entered the single-blind phase, and 63 were randomized to pregabalin CR and 58 to placebo. The median time to LTR (Kaplan-Meier analysis) was significantly longer in the pregabalin CR group than placebo (58 vs. 22 days, p = 0.02). By trial end, 34/63 (54.0%) pregabalin CR and 41/58 (70.7%) placebo patients experienced LTR. Significantly more patients reported 'benefit from treatment' (Benefit, Satisfaction, and Willingness to Continue Scale) in the pregabalin CR group; no other secondary endpoints were statistically significant. Most AEs were mild to moderate in severity (most frequent: dizziness, somnolence). The percentage of pregabalin CR patients discontinuing because of AEs was 12.2% and 4.8% in the single-blind and double-blind phases, respectively (placebo, 0%).

CONCLUSIONS

Time to LTR was significantly longer with pregabalin CR versus placebo in fibromyalgia patients who initially showed improvement with pregabalin CR, indicating maintenance of response. Pregabalin CR was well tolerated in most patients. Generalizability may be limited by study duration and selective population.

Information for physicians and pharmacists about drugs that might cause dry mouth: a study of monographs and published literature

BACKGROUND

Over three-quarters of the older population take medications that can potentially cause dry mouth. Physicians or pharmacists rarely inform patients about this adverse effect and its potentially severe damage to the teeth, mouth and general health.

OBJECTIVES

The objectives of this study were to (1) identify warnings in the literature about dry mouth associated with the most frequently prescribed pharmaceutical products in Canada; and (2) consider how this information might be obtained by physicians, pharmacists and patients.

METHODS

Monographs on the 72 most frequently prescribed medications during 2010 were retrieved from the Compendium of Pharmaceuticals and Specialties (CPS, a standard drug information reference for physicians and pharmacists), the National Library of Medicine's 'DailyMed' database, directly from the manufacturers, and from a systematic search of biomedical journals.

RESULTS

The CPS provided monographs for 43% of the medications, and requests to manufacturers produced the remaining monographs. Mentions of dry mouth were identified in 61% of the products (43% amongst CPS monographs; an additional 43% amongst manufacturers' monographs; 7% in the DailyMed database and 7% from biomedical journals); five medications had contradictory reports in different monographs.

CONCLUSION

Nearly two-thirds (61%) of the most commonly prescribed medications can cause dry mouth, yet warnings about this adverse effect and its potentially serious consequences are not readily available to physicians, pharmacists, dentists or patients.

Update on neuropathic pain treatment: ion channel blockers and gabapentinoids

Neuropathic pain is a debilitating chronic pain condition, which remains difficult to treat. The current mainstays of treatment include physical therapy, interventional procedures and medications. Among medications, ion channel blockers and gabapentinoids are the 2 classes of drugs commonly used to treat neuropathic pain. It has been suggested that these medications may be useful to treat a variety of neuropathic pain conditions. This article provides several updates on the utility of both ion channel blockers and gabapentinoids for the treatment of neuropathic pain.

Combining cognitive-behavioral therapy and milnacipran for fibromyalgia: a feasibility randomized-controlled trial

OBJECTIVES

To evaluate the feasibility of a randomized-controlled trial and to obtain estimates of the effects of combined cognitive-behavioral therapy (CBT) and milnacipran for the treatment of fibromyalgia.

METHODS

Fifty-eight patients with fibromyalgia were randomized to 1 of the 3 treatment arms: (1) combination therapy (n = 20); (2) milnacipran+education (n = 19); and (3) placebo+CBT (n = 19). Patients received either milnacipran (100 mg/d) or placebo. Patients also received 8 sessions of phone-delivered CBT or educational instructions, but only from baseline to week 9. Assessments were conducted at baseline, week 9, and 21. The primary endpoints were baseline to week 21 changes in weekly average pain intensity and physical function (SF-36 physical function scale).

RESULTS

Compared with milnacipran, combination therapy demonstrated a moderate effect on improving SF-36 physical function (SE = 9.42 [5.48], P = 0.09, effect size = 0.60) and in reducing weekly average pain intensity (mean difference [SE] = -1.18 [0.62], P = 0.07, effect size = 0.67). Compared with milnacipran, CBT had a moderate to large effect in improving SF-36 physical function (mean difference [SE] = 11.0 [5.66], P = 0.06, effect size = 0.70). Despite the presence of concomitant centrally acting therapies, dropout rate was lower than anticipated (15% at week 21). Importantly, at least 6 out of the 8 phone-based therapy sessions were successfully completed by 89% of the patients; and adherence to the treatment protocols was > 95%.

CONCLUSIONS

In this pilot study, a therapeutic approach that combines phone-based CBT and milnacipran was feasible and acceptable. Moreover, the preliminary data supports conducting a fully powered randomized-controlled trial.

Pregabalin in neuropathic pain: evidences and possible mechanisms

Pregabalin is an antagonist of voltage gated Ca2+ channels and specifically binds to alpha-2-delta subunit to produce antiepileptic and analgesic actions. It successfully alleviates the symptoms of various types of neuropathic pain and presents itself as a first line therapeutic agent with remarkable safety and efficacy. Preclinical studies in various animal models of neuropathic pain have shown its effectiveness in treating the symptoms like allodynia and hyperalgesia. Clinical studies in different age groups and in different types of neuropathic pain (peripheral diabetic neuropathy, fibromyalgia, post-herpetic neuralgia, cancer chemotherapy-induced neuropathic pain) have projected it as the most effective agent either as monotherapy or in combined regimens in terms of cost effectiveness, tolerability and overall improvement in neuropathic pain states. Preclinical studies employing pregabalin in different neuropathic pain models have explored various molecular targets and the signaling systems including Ca2+ channel-mediated neurotransmitter release, activation of excitatory amino acid transporters (EAATs), potassium channels and inhibition of pathways involving inflammatory mediators. The present review summarizes the important aspects of pregabalin as analgesic in preclinical and clinical studies as well as focuses on the possible mechanisms.

Pregabalin rectifies aberrant brain chemistry, connectivity, and functional response in chronic pain patients

BACKGROUND

Chronic pain remains a significant challenge for modern health care as its pathologic mechanisms are largely unknown and preclinical animal models suffer from limitations in assessing this complex subjective experience. However, human brain neuroimaging techniques enable the assessment of functional and neurochemical alterations in patients experiencing chronic pain and how these factors may dynamically change with pharmacologic treatment.

METHODS

To identify the clinical action of pregabalin, a proven analgesic, the authors performed three complementary brain neuroimaging procedures: (proton magnetic resonance spectroscopy, functional magnetic resonance imaging, and functional connectivity magnetic resonance imaging) in 17 chronic pain patients diagnosed with fibromyalgia.

RESULTS

The authors found that pregabalin but not placebo reduces combined glutamate + glutamine levels within the posterior insula (pregabalin P = 0.016; placebo P = 0.71). Interestingly, reductions in clinical pain were associated with reductions in brain connectivity of this structure to brain regions within the default mode network during pregabalin (r = 0.82; P = 0.001) but not placebo (r = -0.13; P = 0.63). Response of default mode network regions to experimental pain was also reduced with pregabalin (P = 0.018) but not placebo (P = 0.182). Perhaps most importantly, baseline values for all three neuroimaging markers predicted subsequent analgesic response to pregabalin but not placebo.

CONCLUSIONS

The results of this study suggest that pregabalin works in part by reducing insular glutamatergic activity, leading to a reduction of the increased functional connectivity seen between brain regions in chronic pain states. The study also supports a role for human brain imaging in the development, assessment, and personalized use of central-acting analgesics.

Juvenile fibromyalgia: current status of research and future developments

Juvenile-onset fibromyalgia (JFM) is a poorly understood chronic pain condition most commonly affecting adolescent girls. The condition is characterized by widespread musculoskeletal pain and other associated symptoms, including fatigue, nonrestorative sleep, headaches, irritable bowel symptoms, dysautonomia and mood disorders such as anxiety and/or depression. In the past few years, there has been a greater focus on understanding JFM in adolescents. Research studies have provided insight into the clinical characteristics of this condition and its effect on both short-term and long-term psychosocial and physical functioning. The importance of early and effective intervention is being recognized, as research has shown that symptoms of JFM tend to persist and do not resolve over time as was previously believed. Efforts to improve treatments for JFM are underway, and new evidence strongly points to the potential benefits of cognitive-behavioural therapy on improving mood and daily functioning. Research into pharmacotherapy and other nonpharmacological options is in progress. Advancements in the understanding of adult fibromyalgia have paved the way for future studies on diagnosis, assessment and management of JFM. This Review focuses on our current knowledge of the condition, provides an update of the latest research advances, and highlights areas for further study.

Interest in yoga among fibromyalgia patients: an international internet survey

Studies in circumscribed clinical settings have reported the adoption of yoga by many fibromyalgia (FM) patients. However, it is unclear from existing studies which types of yoga practices FM patients are typically engaging in and the extent to which they experience yoga as helpful or not. The purpose of this study was to survey FM patients in many different regions to inquire about their engagement in various yoga practices, the perceived benefits, and the obstacles to further practice. A 13-question Internet survey of persons self-identified as FM patients was conducted among subscribers to 2 electronic newsletters on the topic of FM. Respondents (N = 2543) replied from all 50 U.S. states and also from Canada, Australia, and the United Kingdom, and from more than two dozen other countries. On average, respondents were 57 years of age and 96% were female, with an average time since diagnosis of 13 years. Of these respondents, 79.8% had considered trying yoga and 57.8% had attended 1 yoga class. The respondents' classes typically focused almost exclusively on yoga poses, with minimal training in meditation, breathing techniques, or other practices. The most commonly cited benefits were reduced stiffness, relaxation, and better balance. The most frequently cited obstacles were concerns about the poses being too physically demanding and fear that the poses would cause too much pain. These findings confirm strong interest in yoga across a geographically diverse range of FM patients. However, concerns about yoga-induced pain and yoga poses being too difficult are common reasons that FM patients do not engage in yoga exercises. This study supports the need for yoga programs tailored for FM patients to include modification of poses to minimize aggravating movements and substantive training in meditation and other yoga-based coping methods to minimize pain-related fear.

Central pain processing in osteoarthritis: implications for treatment

SUMMARY Osteoarthritis (OA) is a major cause of pain and is characterized by loss of articular cartilage integrity, synovitis and remodeling of subchondral bone. However, OA pain mechanisms remain incompletely understood. Pain severity does not always correlate with the extent of joint damage. Furthermore, many people with OA continue to experience pain despite optimal use of standard therapies that target the joints, including joint-replacement surgery. There is compelling evidence that altered central pain processing plays an important role in maintaining pain and increasing pain severity in some people with OA. A key challenge is to identify this subgroup of patients with abnormal central pain processing in order to improve their clinical outcomes by developing and targeting specific analgesic treatments.

Fibromyalgia

Fibromyalgia is a chronic pain condition present in 2-4% of the population. Fibromyalgia consists of widespread pain with similarities to neuropathic pain in clinical findings, pathophysiology, and neuropharmacology. Pain is the predominant symptom and allodynia and hyperalgesia are common signs. Extreme fatigue, impaired cognition and nonrestorative sleep difficulties coexist in addition to other somatic symptoms. Research including neuroimaging investigations shows abnormalities in neurotransmitters and an abnormal response to pain. Altered pain processing peripherally and centrally contribute to central sensitization and a dampened effect of the diffuse noxious inhibitory control (DNIC). Successful management incorporates education of the patient in self-management skills, cognitive behavioral therapy (CBT), exercise, and drug therapy. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors (SNRIs) (duloxetine and milnacipran), α2-δ ligands (gabapentin and pregabalin) are effective in reducing pain by≥30%. Some success has been shown with dopamine agonists (pramipexole), tramadol, other opioids and cannabinoids (nabilone). Further evidence-based trials using complementary treatments are needed. Fibromyalgia is complex and requires a multidisciplinary approach to treatment. Patient self-management is key.

A systematic cost-effectiveness analysis of pregabalin in the management of fibromyalgia: an Iranian experience

INTRODUCTION

Fibromyalgia is a neuropathic syndrome which is more common in adult females. Pregabalin is the first medicine which was approved by the United States Food and Drug Administration for treatment of fibromyalgia. In this study we aimed to evaluate the cost-efficacy of pregabalin in the treatment of fibromyalgia in Iran.

MATERIAL AND METHODS

To evaluate the efficacy of pregabalin, a systematic review was carried out by conducting a wide literature search for the main outcomes of interest that were pain score reduction from the baseline and the percentage of patients with more than 50% pain reduction. To evaluate costs of treatment, only the direct medical costs were considered. The calculated incremental cost-effectiveness ratio (ICER) were compared with one and three times the gross domestic product (GDP) per capita as the threshold to evaluate the economic condition of treatment to be "highly cost-effective", "cost-effective" or "not cost-effective".

RESULTS

Out of 4012 searched reports, only four reports were included in the study, all of which were randomized controlled trials with placebo controls. The calculated ICERs for pregabalin 450 mg/day and 600 mg/day with both available forms of brand and generic medicines in the country were in the range of 44-1170 US dollars (USD) and 48-814 USD, which in all cases could be considered as highly cost-effective. Pregabalin 150 mg/day based on available evidence does not have significant efficacy in comparison to placebo. But for pregabalin 300 mg/day, no decision can be made based on current data.

CONCLUSIONS

Our analysis indicated that generic pregabalin in the treatment doses of 450 mg/day and 600 mg/day is highly cost-effective.

Anticonvulsants for fibromyalgia

BACKGROUND

Fibromyalgia (FM) is a clinically well-defined chronic condition of unknown aetiology characterised by chronic widespread pain that often co-exists with sleep problems and fatigue. People often report high disability levels and poor health-related quality of life (HRQoL). Drug therapy focuses on reducing key symptoms and disability, and improving HRQoL. Anticonvulsants (antiepileptic drugs) are drugs frequently used for the treatment of chronic pain syndromes.

OBJECTIVES

To assess the benefits and harms of anticonvulsants for treating FM symptoms.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 8, 2013), MEDLINE (1966 to August 2013), PsycINFO (1966 to August 2013), SCOPUS (1980 to August 2013) and the reference lists of reviewed articles for published studies and www.clinicaltrials.gov (to August 2013) for unpublished trials.

SELECTION CRITERIA

We selected randomised controlled trials of any formulation of anticonvulsants used for the treatment of people with FM of any age.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data of all included studies and assessed the risks of bias of the studies. We resolved discrepancies by discussion.

MAIN RESULTS

We included eight studies: five with pregabalin and one study each with gabapentin, lacosamide and levetiracetam. A total of 2480 people were included into anticonvulsants groups and 1099 people in placebo groups. The median therapy phase of the studies was 13 weeks. The amount and quality of evidence were insufficient to draw definite conclusions on the efficacy and safety of gabapentin, lacosamide and levetiracetam in FM. The amount and quality of evidence was sufficient to draw definite conclusions on the efficacy and safety of pregabalin in FM. Therefore, we focused on our interpretation of the evidence for pregabalin due to our greater certainty about its effects and its greater relevance to clinical practice. All pregabalin studies had a low risk of bias. Reporting a 50% or greater reduction in pain was more frequent with pregabalin use than with a placebo (risk ratio (RR) 1.59; 95% confidence interval (CI) 1.33 to 1.90; number needed to treat for an additional beneficial outcome (NNTB) 12; 95% CI 9 to 21). The number of people who reported being 'much' or 'very much' improved was higher with pregabalin than with placebo (RR 1.38; 95% CI 1.23 to 1.55; NNTB 9; 95% CI 7 to 15). Pregabalin did not substantially reduce fatigue (SMD -0.17; 95% CI -0.25 to -0.09; 2.7% absolute improvement on a 1 to 50 scale) compared with placebo. Pregabalin had a small benefit over placebo in reducing sleep problems by 6.2% fewer points on a scale of 0 to 100 (standardised mean difference (SMD) -0.35; 95% CI -0.43 to -0.27). The dropout rate due to adverse events was higher with pregabalin use than with placebo use (RR 1.68; 95% CI 1.36 to 2.07; number needed to treat for an additional harmful outcome (NNTH) 13; 95% CI 9 to 23). There was no significant difference in serious adverse events between pregabalin and placebo use (RR 1.03; 95% CI 0.71 to 1.49). Dizziness was reported as an adverse event more frequently with pregabalin use than with placebo use (RR 3.77; 95% CI 3.06 to 4.63; NNTH 4; 95% CI 3 to 5).

AUTHORS' CONCLUSIONS

The anticonvulsant, pregabalin, demonstrated a small benefit over placebo in reducing pain and sleep problems. Pregabalin use was shown not to substantially reduce fatigue compared with placebo. Study dropout rates due to adverse events were higher with pregabalin use compared with placebo. Dizziness was a particularly frequent adverse event seen with pregabalin use. At the time of writing this review, pregabalin is the only anticonvulsant drug approved for treating FM in the US and in 25 other non-European countries. However, pregabalin has not been approved for treating FM in Europe. The amount and quality of evidence were insufficient to draw definite conclusions on the efficacy and safety of gabapentin, lacosamide and levetiracetam in FM.

Evaluation of the effectiveness of pregabalin in alleviating pain associated with fibromyalgia: using functional magnetic resonance imaging study

Purpose

To assess the efficacy of pregabalin by showing differences in the neuronal activities of fibromyalgia (FM) patients before and after longitudinal treatment using functional magnetic resonance imaging (fMRI).

Materials and Methods

In total, 21 female patients with FM and 11 age- and gender-matched healthy controls participated. FM patients underwent fMRI at baseline and following pharmacological therapy with pregabalin to diminish their pain. Pressure-pain stimuli were delivered on the subject’s thumbnail bed during fMRI scans. Brain activation regions in fMRI were evaluated for longitudinal changes using a paired t-test. Changes in clinical features were also assessed with the Fibromyalgia Impact Questionnaire (FIQ), Brief Fatigue Inventory (BFI), Beck Depression Inventory (BDI), Widespread Pain Index (WPI), Symptom Severity Scale Score (SSS), and State-Trait Anxiety Inventory (STAI).

Results

Clinical scores were reduced significantly following therapy with five of the six clinical tests (FIQ, BFI, BDI, WPI, SSS; p < 0.05). Brain activation post-treatment was significantly lower than that pre-treatment in 13 regions of the brain (p < 0.001).

Conclusions

Our findings confirm that pregabalin influences aspects of the whole pain matrix, using fMRI, inducing longitudinal changes in neuronal activity during the pain state, and that it reduces pain and other core symptoms of FM. This method could be applied to other longitudinal clinical trials of pharmacological treatments for FM.

Chronic opioid use in fibromyalgia syndrome: a clinical review

Chronic opioid therapy in the treatment of chronic nonmalignant pain has increased drastically over the past decade. This is a worrisome trend in general, but specifically, given pathophysiologic characteristics seen in fibromyalgia (FM) syndrome patients, the use of this class of medication deserves special scrutiny. We first describe the current understanding of the etiology and pathophysiology of FM, including the role of genetic and environmental factors in the development of this syndrome. We then discuss the biologic effects of opioid use. Next, we review the pharmaceutical treatment options for FM, including 3 Food and Drug Administration-approved medications, and the evolution of treatment guidelines since 2004. We then highlight the various consequences associated with the mechanism of action of opioids and the specific concerns for FM patients.Finally, summarizing the existing literature, we make the case that chronic opioid use is inappropriate in the treatment of FM because of the interaction of unique pathophysiologic characteristics of the patients and effects associated with chronic opioid use.

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.

Fibromyalgia syndrome--novel therapeutic targets

Fibromyalgia is a syndrome characterized by the presence of chronic widespread pain, representing sensitization of the central nervous system. The pthophysiology of fibromyalgia is a complex and remains in evolution, encompassing diverse issues such as disturbed patterns of sleep, alter processing and decreased conditioned pain modulation at the spinal level, as well as increased connectivity between various pain - processing areas of the brain. This evolution is continuously uncovering potential novel therapeutic targets. Treatment of fibromyalgia is a multi - faceted endeavor, inevitably combining pharmacological as well as non - pharmacological approaches. 2δ ligands and selective nor-epinephrine - serotonin reuptake inhibitors are the current mainstays of pharmacological treatment. Novel re-uptake inhibitors targeting both nor -epinephrine and dopamine are potential additions to this armamentarium as are substance P antagonists, Opiod antagonism is another intriguing possibility. Canabinoid agonists hold promise in the treatment of fibromyalgia although current evidence is incomplete. Sodium Oxybate is a unique sleep - promoting medication while drugs those promot arousals such as modafilnil are also under investigation. In the current review, current and emerging therapeutic options for the syndrome of fibromyalgia are covered.

Interpreting effect sizes and clinical relevance of pharmacological interventions for fibromyalgia

Duloxetine, milnacipran, and pregabalin are approved by the United States Food and Drug Administration for the management of fibromyalgia. A number of meta-analyses, pooled analyses, and systematic reviews have been published in recent years involving the efficacy of these three medications for pain in fibromyalgia. Despite being based on the same clinical data, some analyses found these treatments to have a clinically relevant effect on pain, while others concluded that the advantages were small or of questionable clinical relevance. This commentary discussed possible reasons behind these differing conclusions and explored ways of evaluating the clinical relevance of pharmacological treatments for fibromyalgia. In particular, we considered: (1) the importance of judicious and careful interpretation of average treatment effect size and the recognition that average treatment effect sizes do not always tell the whole story; (2) the utility of individual patient response data to assess clinical relevance; and (3) the importance of considering pain reduction within the context of other benefits due to the presence of associated symptoms in patients with fibromyalgia.

Complementary and alternative exercise for fibromyalgia: a meta-analysis

Complementary and alternative medicine includes a number of exercise modalities, such as tai chi, qigong, yoga, and a variety of lesser-known movement therapies. A meta-analysis of the current literature was conducted estimating the effect size of the different modalities, study quality and bias, and adverse events. The level of research has been moderately weak to date, but most studies report a medium-to-high effect size in pain reduction. Given the lack of adverse events, there is little risk in recommending these modalities as a critical component in a multimodal treatment plan, which is often required for fibromyalgia management.

Direct medical costs and medication compliance among fibromyalgia patients: duloxetine initiators vs. pregabalin initiators

OBJECTIVES

To assess and compare direct medical costs and medication compliance between patients with fibromyalgia who initiated duloxetine and patients with fibromyalgia who initiated pregabalin in 2008.

METHODS

A retrospective cohort study design was used based on a large US national commercial claims database (2006 to 2009). Patients with fibromyalgia aged 18 to 64 who initiated duloxetine or pregabalin in 2008 and who had continuous health insurance 1 year preceding and 1 year following the initiation were selected into duloxetine cohort or pregabalin cohort based on their initiated agent. Medication compliance was measured by total supply days, medication possession ratio (MPR), and proportion of patients with MPR ≥ 0.8. Direct medical costs were measured by annual costs per patient and compared between the cohorts in the year following the initiation. Propensity score stratification and bootstrapping methods were used to adjust for distribution bias, as well as cross-cohort differences in demographic, clinical and economic characteristics, and medication history prior to the initiation.

RESULTS

Both the duloxetine (n = 3,033) and pregabalin (n = 4,838) cohorts had a mean initiation age around 49 years, 89% were women. During the postindex year, compared to the pregabalin cohort, the duloxetine cohort had higher totally annual supply days (273.5 vs. 176.6, P < 0.05), higher MPR (0.7 vs. 0.5, P < 0.05), and more patients with MPR ≥ 0.8 (45.1% vs. 29.4%, P < 0.05). Further, relative to pregabalin cohort, duloxetine cohort had lower inpatient costs ($2,994.9 vs. $4,949.6, P < 0.05), lower outpatient costs ($8,259.6 vs. $10,312.2, P < 0.05), similar medication costs ($5,214.6 vs. $5,290.8, P > 0.05), and lower total medical costs ($16,469.1 vs. $20,552.6, P < 0.05) in the postinitiation year.

CONCLUSIONS

In a real-world setting, patients with fibromyalgia who initiated duloxetine in 2008 had better medication compliance and consumed less inpatient, outpatient, and total medical costs than those who initiated pregabalin.

Myofascial pain syndrome: a treatment review

Myofascial pain syndrome (MPS) is defined as pain that originates from myofascial trigger points in skeletal muscle. It is prevalent in regional musculoskeletal pain syndromes, either alone or in combination with other pain generators. The appropriate evaluation and management of myofascial pain is an important part of musculoskeletal rehabilitation, and regional axial and limb pain syndromes. This article reviews the current hypotheses regarding the treatment modalities for myofascial trigger points and muscle pain. Through a critical evidence-based review of the pharmacologic and nonpharmacologic treatments, the authors aim to provide clinicians with a more comprehensive knowledge of the interventions for myofascial pain.

[Psychopharmacological treatment in patients with somatoform disorders and functional body syndromes]

Somatoform disorders and functional body syndromes define a major, diagnostically heterogeneous group of patients with medically unexplained physical symptoms. Psychopharmacological approaches can be derived from the conceptualization of somatoform symptoms and syndromes within a biopsychosocial model. The survey presented focuses on randomized, double-blind and placebo-controlled studies. Antidepressants show a statistically and clinically relevant impact on many somatoform symptoms. In special reference to pain symptoms serotonergic and noradrenergic antidepressants seem to mediate a more favorable effect than selective serotonin reuptake inhibitors. For some functional body syndromes, e.g. irritable bowel syndrome and fibromyalgia, a major analgesic effect of antidepressants can be underlined as well. The empirical data for fibromyalgia, however, seem to be more convincing than for irritable bowel syndrome. Pregabalin holds an empirically well established position in the treatment of fibromyalgia. As yet there is no convincing psychopharmacological strategy for chronic fatigue syndrome. Probably due to the inherent relationships to anxiety, obsessive-compulsive and depressive disorders, both hypochondria and body dysmorphic disorder can be positively treated by serotonergic antidepressants as well.

Adjunctive pregabalin in partial responders with major depressive disorder and residual anxiety

BACKGROUND

Anxiety symptoms in depression result often in treatment resistance, residual symptoms, and persistent functional impairment.

OBJECTIVE

To assess the effectiveness and safety of adjunctive pregabalin to antidepressants for residual anxiety in patients with major depressive disorder (MDD).

METHODS

A retrospective chart review was conducted to identify partial responders among patients with MDD with residual anxiety. Twenty such patients (age, 58.4 ± 11.2 years; 15 women; baseline Hamilton Depression Rating Scale [HDRS], 17.1 ± 3.5) who received adjunctive pregabalin for residual anxiety were included. Antidepressants augmented were the selective serotonin reuptake inhibitors (n = 12), mirtazapine (n = 2), and selective serotonin-norepinephrine reuptake inhibitors (n = 6).

RESULTS

Twenty patients received at least 4 weeks of pregabalin treatment after 8 weeks of antidepressant therapy. At week 1 (9 weeks after initiating treatment), pregabalin was prescribed at a mean ± SD dose of 71.2 ± 31.7 mg, and the mean maximum pregabalin dose prescribed was 156.2 ± 76.5 mg (range, 75-300 mg). At week 8, there were 13 responders (13/20 [65%]), and 7 of these 13 patients achieved remission (HDRS17 < 8). There were significant decreases in HDRS scores (13.5 ± 3.1 vs 9.1 ± 2.9, P < 0.000), and HDRS anxiety/somatization subscale scores (6.3 ± 2 to 3.6 ± 1.7, P < 0.000). Adverse effects included somnolence (n = 7), weight gain (n = 3), dizziness (n = 4), dry mouth (n = 6), edema (n = 3), blurred vision (n = 3), difficulty with concentration/attention (n = 8), headache (n = 6), and diarrhea (n = 5).

CONCLUSIONS

The results suggest a possible augmentation role for pregabalin when used in conjunction with conventional antidepressants for residual anxiety in MDD.

[Drug therapy of fibromyalgia syndrome. Systematic review, meta-analysis and guideline]

BACKGROUND

The scheduled update to the German S3 guidelines on fibromyalgia syndrome (FMS) by the Association of the Scientific Medical Societies ("Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften", AWMF; registration number 041/004) was planned starting in March 2011.

MATERIALS AND METHODS

The development of the guidelines was coordinated by the German Interdisciplinary Association for Pain Therapy ("Deutsche Interdisziplinären Vereinigung für Schmerztherapie", DIVS), 9 scientific medical societies and 2 patient self-help organizations. Eight working groups with a total of 50 members were evenly balanced in terms of gender, medical field, potential conflicts of interest and hierarchical position in the medical and scientific fields. Literature searches were performed using the Medline, PsycInfo, Scopus and Cochrane Library databases (until December 2010). The grading of the strength of the evidence followed the scheme of the Oxford Centre for Evidence-Based Medicine. The recommendations were based on level of evidence, efficacy (meta-analysis of the outcomes pain, sleep, fatigue and health-related quality of life), acceptability (total dropout rate), risks (adverse events) and applicability of treatment modalities in the German health care system. The formulation and grading of recommendations was accomplished using a multi-step, formal consensus process. The guidelines were reviewed by the boards of the participating scientific medical societies.

RESULTS AND CONCLUSION

Amitriptyline and-in case of comorbid depressive disorder or generalized anxiety disorder-duloxetine are recommended. Off-label use of duloxetine and pregabalin can be considered in case of no comorbid mental disorder. Strong opioids are not recommended. The English full-text version of this article is available at SpringerLink (under "Supplemental").

Long-term maintenance of response across multiple fibromyalgia symptom domains in a randomized withdrawal study of pregabalin

OBJECTIVE

To determine the incidence and duration of response of clinically meaningful improvements with pregabalin across several key symptoms of fibromyalgia (FM).

METHODS

This was a post hoc analysis of data from a multicenter, double-blind, placebo-controlled, randomized, withdrawal study, originally designed to evaluate the efficacy of pregabalin monotherapy for durability of effect on FM pain based on pain and Patient Global Impression of Change (PGIC) criteria. Responder criteria for Fibromyalgia Impact Questionnaire total score (≥16-point change), Medical Outcomes Study Sleep Scale Sleep Disturbance subscale (≥15.8-point change), and the 36-item Short-Form Health Survey Vitality scale (≥10-point change) were used to evaluate the incidence and duration of improvements in function, sleep, and fatigue for pregabalin versus placebo among pain and PGIC responders. A composite responder index consisting of pain, PGIC, function, and sleep endpoints was used to explore multidimensional response.

RESULTS

Approximately 80% of patients meeting pain and PGIC improvement criteria at randomization had clinically meaningful improvement in fatigue, sleep, or function. Higher proportions of patients in the pregabalin group maintained a clinically meaningful response, and pregabalin-treated patients had a significantly longer time to loss of therapeutic response compared with the placebo group. Composite responder Kaplan-Meier analysis, performed with patients demonstrating clinically meaningful improvements in pain, PGIC, function, and sleep at randomization showed a significantly longer median time to loss of therapeutic response for pregabalin-treated patients.

DISCUSSION

The results from this post hoc analysis indicate that pregabalin provides long-term effects across multiple domains of FM (ClinicalTrials.gov registry ID: NCT00151489).

Evaluation of the fibromyalgia impact questionnaire at baseline as a predictor for time to pain improvement in two clinical trials of pregabalin

BACKGROUND

The Fibromyalgia Impact Questionnaire (FIQ) is a patient-reported outcome that evaluates the impact of fibromyalgia (FM) on daily life. This study evaluated the relationships between the functional status of FM patients, measured with the FIQ at baseline, and median time to a clinically relevant pain reduction.

METHODS

Data were derived from two randomised, placebo-controlled trials that evaluated pregabalin 300, 450 and 600 mg/day for the treatment of FM. The Kaplan-Meier (nonparametric) method was applied to estimate median times to 'transient' and 'stable' events. The transient event was defined as a ≥ 27.9% improvement on an 11-point daily pain diary scale (0 = no pain, 10 = worst possible pain), and the stable event was defined as the mean of the daily improvements ≥ 27.9% relative to baseline over the subsequent study duration starting on the day of the transient event. A parametric model using time-to-event analysis was developed for evaluating the relationship between baseline FIQ score and the median time to these events.

RESULTS

Median time was longer among patients treated with placebo relative to pregabalin for the transient events (11-12 days vs. 5-7 days) and stable events (86 days vs. 13-29 days). A significant association was observed between baseline FIQ scores and median time to transient and stable events (p < 0.001). Median times to events were similar between the studies. For transient pain reduction events, median times ranged from 3.0 to 4.5 days for baseline FIQ scores of 10, and 9.1-9.6 days for FIQ scores of 100; for stable pain reduction events, the median time ranged from 11.0 to 13.0 days and from 27.0 to 28.5 days for baseline FIQ scores of 10 and 100 respectively.

CONCLUSIONS

Time to a clinically relevant reduction in pain was significantly associated with FM severity at baseline as measured by the FIQ. Such an analysis can inform patient and physician expectations in clinical practice.

Enantioseparations by high-performance liquid chromatography using macrocyclic glycopeptide-based chiral stationary phases: an overview

Since their introduction by Armstrong in 1994, macrocyclic 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, hydroxyl, amino and carboxyl groups, halogen atoms, aromatic moieties, etc.) are the reason 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 use of macrocyclic antibiotic-based stationary phases in HPLC enantioseparations. This overview chapter provides a brief summary of general aspects of macrocyclic antibiotic-based chiral stationary phases including their preparation and their application to direct enantioseparations of various racemates focusing on the literature published since 2004.

A comparative bioavailability study of two formulations of pregabalin in healthy Chilean volunteers

OBJECTIVE

The aim of this study was to compare the pharmacokinetic parameters between two brands of pregabalin in healthy Chilean volunteers.

METHODS

A randomized, single-dose, two-period, two-sequence, crossover study design with a 2-week washout period was conducted in healthy Chilean males. Plasma samples were collected over a 12-hour period after administration of 150 mg pregabalin in each period. A validated ultra-performance liquid chromatography with positive ionization mass spectrometric detection method was used to analyze pregabalin concentration in plasma. Pharmacokinetic parameters were determined using a noncompartmental method. Bioequivalence between the test and reference products was determined when the ratio for the 90% confidence intervals (CIs) of the difference in the means of the log-transformed area under the curve (AUC)(0-t), AUC(0-∞), and maximum concentration (C(max)) of the two products were within 0.80 and 1.25.

RESULTS

The study was carried out on 22 healthy Chilean volunteers. The mean (SD) C(max), AUC(0-t) and AUC(0-∞) of the test formulation (Pregobin™) of pregabalin were 2.10 (0.56) μg/ml, 10.35 (2.00) μgxh/ml and 13.92 (2.74) μgxh/ml, respectively. The mean (SD) C(max), AUC(0-t) and AUC(0-∞) of the reference formulation (Lyrica™) of pregabalin were 2.15 (0.52) μg/ml, 10.31 (1.85) μgxh/ml and 13.78 (2.25) μgxh/ml, respectively. The parametric 90% CIs for C(max), AUC(0-t), and AUC(0-∞) were 0.97-1.13, 1.01-1.04, and 0.98-1.02, respectively.

CONCLUSIONS

These results suggest that both products are bioequivalent and can be used as interchangeable options in the clinical setting.

An open-label long-term phase III extension trial to evaluate the safety and efficacy of pregabalin in Japanese patients with fibromyalgia

OBJECTIVES

To assess the long-term safety and efficacy of pregabalin for the treatment of Japanese patients with fibromyalgia (FM).

METHODS

This 53-week, open-label extension study was conducted at 20 study sites in Japan in patients with FM who had completed a preceding 16-week, placebo-controlled, double-blind trial. Patients received pregabalin, starting at 150 mg/day and increasing to a maintenance dose of 300 or 450 mg/day. The primary endpoint was safety, and secondary endpoints included measures of pain, sleep, and physical functioning.

RESULTS

106 patients entered the trial and received at least one dose of the study drug. The most common treatment-related adverse events were somnolence, dizziness, increased weight, and constipation. There were no treatment-related serious or severe adverse events. There were five (4.7%) discontinuations due to adverse events, of which three (2.8%) were considered related to the study drug. Most adverse events resolved over time and could be managed without dose reduction or treatment discontinuation. Improvements in secondary efficacy endpoints of pain, sleep, and physical functioning emerged early in the study and were maintained for the duration of treatment.

CONCLUSIONS

These data indicate that the long-term treatment of Japanese FM patients with pregabalin may be both safe and effective.

A randomized, double-blind, multicenter, placebo-controlled phase III trial to evaluate the efficacy and safety of pregabalin in Japanese patients with fibromyalgia

Introduction

Fibromyalgia is a chronic disorder characterized by widespread pain and tenderness. Prior trials have demonstrated the efficacy of pregabalin for the relief of fibromyalgia symptoms, and it is approved for the treatment of fibromyalgia in the United States. However, prior to this study, there has not been a large-scale efficacy trial in patients with fibromyalgia in Japan.

Methods

This randomized, double-blind, multicenter, placebo-controlled trial was conducted at 44 centers in Japan to assess the efficacy and safety of pregabalin for the symptomatic relief of pain in fibromyalgia patients. Patients aged ≥18 years who had met the criteria for fibromyalgia were randomized to receive either pregabalin, starting at 150 mg/day and increasing to a maintenance dose of 300 or 450 mg/day, or placebo, for 15 weeks. The primary efficacy endpoint was mean pain score at final assessment. Secondary endpoints included Patient Global Impression of Change (PGIC) together with measures of sleep, physical functioning and quality of life.

Results

A total of 498 patients (89% female) were randomized to receive either pregabalin (n = 250) or placebo (n = 248). Pregabalin significantly reduced mean pain score at final assessment (difference in mean change from baseline, compared with placebo -0.44; P = 0.0046) and at every week during the study (P <0.025). Key secondary endpoints were also significantly improved with pregabalin treatment compared with placebo, including PGIC (percentage reporting symptoms "very much improved" or "much improved", 38.6% vs 26.7% with placebo; P = 0.0078); pain visual analog scale (difference in mean change from baseline, compared with placebo -6.19; P = 0.0013); Fibromyalgia Impact Questionnaire total score (-3.33; P = 0.0144); and quality of sleep score (-0.73; P <0.0001). Treatment was generally well tolerated, with somnolence and dizziness the most frequently reported adverse events.

Conclusions

This trial demonstrated that pregabalin, at doses of up to 450 mg/day, was effective for the symptomatic relief of pain in Japanese patients with fibromyalgia. Pregabalin also improved measures of sleep and functioning and was well tolerated. These data indicate that pregabalin is an effective treatment option for the relief of pain and sleep problems in Japanese patients with fibromyalgia.

Trial Registration

ClinicalTrials.gov: NCT00830167

Treatment of fibromyalgia: a changing of the guard

Fibromyalgia remains one of the most common and enigmatic musculoskeletal disorders among patients with pain and, until recently, few effective treatments have been discovered. This review will briefly consider the rationale supporting traditional treatment options and their efficacy, including the role of exercise and pharmacotherapy. Juxtaposed with these common approaches to relieve fibromyalgia pain and fatigue are the promising new medications that are being developed, such as pregabalin, milnacipran, duloxetine, sodium oxybate, ropinirole and pramipexole. Outcomes from recent randomized trials will be reviewed and compared.

Clinical characteristics of 150 consecutive fibromyalgia patients attending an Australian public hospital clinic

AIM

To describe clinical characteristics of fibromyalgia in an Australian population.

METHOD

Data was collected from 150 consecutive patients with clinical features of fibromyalgia seen in an Australian public hospital clinic. Demographic information and clinical characteristics were recorded. Significant correlations between clinical characteristics were identified, then used in multiple regression analyses to identify factors influencing outcome in physical function, pain, fatigue and sleep disturbance. Clinical features in groups who were or were not using different treatment strategies were compared.

RESULTS

Most patients were female and Caucasian. The majority reported a recognizable trigger factor and many had associated conditions, most commonly headache and irritable bowel syndrome. Physical function was significantly accounted for by pain levels (P = 0.001); pain score was significantly predicted by tenderness (P = 0.002) and physical function level (P = 0.001); fatigue levels were significantly influenced by age (P = 0.007) and sleep disturbance (P < 0.001), and sleep disturbance was significantly predicted by fatigue (P < 0.001). Just over one-third (34%) of patients were using fibromyalgia medications (low-dose tricyclic antidepressant, pregabalin or duloxetine); however, they had less anxiety (P = 0.006) and better reported physical function (P = 0.04) than those who were not. Less than half (43.6%) of the patients were regularly exercising; however, they had reduced overall illness impact scores (P = 0.004), better physical function (P = 0.01) and less fatigue (P = 0.03), anxiety (P = 0.02) and depressive features (P = 0.008) than non-exercisers.

CONCLUSION

Baseline clinical characteristics in this group were comparable to other study populations. The use of management modalities with proven benefit in fibromyalgia was limited; however, those patients who were engaged in regular exercise or using medication had better self-reported outcome measures than those who were not.