An open-label, long-term, phase III extension trial of duloxetine in Japanese patients with fibromyalgia

Fibromyalgia

Fibromyalgia is characterized by chronic, widespread musculoskeletal pain and associated fatigue, sleep disturbances, and other cognitive and somatic symptoms. For many patients, these symptoms persist for years and lead to frequent health care use; for some, fibromyalgia and its symptoms can be debilitating. Although many treatments are available, management remains challenging. This article highlights the clinical features of fibromyalgia, discusses diagnostic criteria and their evolution, and reviews treatment options.

A Systematic Review of Efficacy, Safety, and Tolerability of Duloxetine

Duloxetine is a serotonin-norepinephrine reuptake inhibitor approved for the treatment of patients affected by major depressive disorder (MDD), generalized anxiety disorder (GAD), neuropathic pain (NP), fibromyalgia (FMS), and stress incontinence urinary (SUI). These conditions share parallel pathophysiological pathways, and duloxetine treatment might be an effective and safe alternative. Thus, a systematic review was conducted following the 2009 Preferred Reporting Items (PRISMA) recommendations and Joanna Briggs Institute Critical (JBI) Appraisals guidelines. Eighty-five studies focused on efficacy, safety, and tolerability of duloxetine were included in our systematic review. Studies were subdivided by clinical condition and evaluated individually. Thus, 32 studies of MDD, 11 studies of GAD, 19 studies of NP, 9 studies of FMS, and 14 studies of SUI demonstrated that the measured outcomes indicate the suitability of duloxetine in the treatment of these clinical conditions. This systematic review confirms that the dual mechanism of duloxetine benefits the treatment of comorbid clinical conditions, and supports the efficacy, safety, and tolerability of duloxetine in short- and long-term treatments.

An Association of Serotonin with Pain Disorders and Its Modulation by Estrogens

Ovarian hormones play an important role in pain perception, and are responsible, at least in part, for the pain threshold differences between the sexes. Modulation of pain and its perception are mediated by neurochemical changes in several pathways, affecting both the central and peripheral nervous systems. One of the most studied neurotransmitters related to pain disorders is serotonin. Estrogen can modify serotonin synthesis and metabolism, promoting a general increase in its tonic effects. Studies evaluating the relationship between serotonin and disorders such as irritable bowel syndrome, fibromyalgia, migraine, and other types of headache suggest a clear impact of this neurotransmitter, thereby increasing the interest in serotonin as a possible future therapeutic target. This literature review describes the importance of substances such as serotonin and ovarian hormones in pain perception and illustrates the relationship between those two, and their direct influence on the presentation of the aforementioned pain-related conditions. Additionally, we review the pathways and receptors implicated in each disorder. Finally, the objective was to stimulate future pharmacological research to experimentally evaluate the potential of serotonin modulators and ovarian hormones as therapeutic agents to regulate pain in specific subpopulations.

An Open-Label, 52-Week, Phase III Trial of Duloxetine in Japanese Patients with Chronic Low Back Pain

Objective

To evaluate the safety and efficacy of duloxetine treatment for 52 weeks.

Design

Multicenter, open-label, phase III clinical study.

Setting

Forty-one medical institutions in Japan.

Subjects

Japanese patients with chronic low back pain (CLBP).

Methods

Duloxetine 60 mg once-daily was administered for 52 weeks. Safety was evaluated based on adverse events (AEs), vital signs, laboratory test values, electrocardiogram, Columbia-Suicide Severity Rating Scale, and occurrence of falls. The efficacy outcome measures were the Brief Pain Inventory (BPI; average pain, worst pain, least pain, and pain right now), BPI Interference, Patient’s Global Impression of Improvement (PGI-I), Clinical Global Impressions of Severity (CGI-S), Roland-Morris Disability Questionnaire–24 (RDQ-24), 36-Item Short-Form Health Survey (SF-36), and European Quality of Life-5 Dimensions Questionnaire (EQ-5D).

Results

In total, 151 patients (83 who completed a 14-week placebo-controlled superiority trial and 68 newly registered patients) were enrolled. The incidence rates of AEs and adverse drug reactions (ADRs) were 86.1% and 50.3%, respectively. ADRs with an incidence of ≥5% were somnolence, constipation, nausea, and dry mouth. Treatment discontinuation for AEs occurred in 16 patients. A significant reduction in the BPI average pain score (mean ± SD) was observed at all assessment time points from week 2 (−1.02 ± 1.37) to week 50 (−2.26 ± 1.63), compared with baseline. BPI pain severity (worst pain, least pain, and pain right now), BPI Interference, PGI-I, CGI-S, RDQ-24, SF-36, and EQ-5D showed significant improvement.

Conclusion

Japanese patients with CLBP had significant pain reduction over 52 weeks without new safety concerns.

Serum levels of serotonin as a biomarker of newly diagnosed fibromyalgia in women: Its relation to the platelet indices

Background:

This study aimed to assess the serum serotonin levels in the newly diagnosed fibromyalgia (FM) and to relate these levels to the presenting signs and symptoms.

Materials and Methods:

This case–control study included 35 healthy women (Group I) served as controls and 130 women with newly diagnosed FM (Group II). The diagnosis of FM was confirmed by the diagnostic criteria of the American College of Rheumatology-10. The assessment of pain using a revised fibromyalgia impact questionnaire and tender points scoring, blood platelet indices, and serum serotonin levels were determined.

Results:

Group II patients had significantly (P < 0.001) higher values of mean platelet volume (MPV) (10.60 ± 1.57fL) and platelet width distribution (16.25 ± 1.45%) than the corresponding values in Group I (8.73 ± 0.81fL and 15.0 ± 1.15%). Significant low-serum serotonin levels observed in Group II patients compared with Group I healthy individuals (187.3 ± 50.3 ng/ml vs. 219.5 ± 78.3 ng/ml, P = 0.026). Multiple linear regression analysis showed the nonsignificant correlations between serum serotonin levels and platelet indices in Group II patients.

Conclusion:

Newly diagnosed FM women have significantly low-serum serotonin levels, which does not correlate with a significant increment of the platelet activity expressed as increase MPV and platelet width distribution percentage. Therefore, this study highlighted that the correction of serum serotonin level by medicines could help the patients.

Safety and efficacy of duloxetine in Japanese patients with chronic knee pain due to osteoarthritis: an open-label, long-term, Phase III extension study

Purpose

To assess long-term safety, tolerability, and efficacy of duloxetine in Japanese patients with chronic knee pain due to osteoarthritis.

Methods

In this open-label extension study (NCT02335346), Japanese patients with knee osteoarthritis and pain (Brief Pain Inventory [BPI] - Severity average pain score ≥4 at start of randomized trial) who had previously received duloxetine 60 mg/day or placebo for 14 weeks in a double-blind randomized trial entered the extension and received duloxetine 60 mg/day for 48 weeks. The primary outcome was safety/tolerability, secondary outcomes were change in BPI-Severity (BPI-S) average pain, BPI-Interference (BPI-I), Patient Global Impression-Improvement (PGI-I), Clinical Global Impression-Improvement (CGI-I), 36-item Short-Form Health Survey (SF36), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and exploratory outcomes were knee range of motion (efficacy outcome) and Kellgren-Lawrence grade (safety outcome).

Results

Of 323 patients who completed the randomized trial, 93 (50 placebo, 43 duloxetine) entered the extension. Most patients (85, 91.4%) experienced an adverse event, most commonly constipation, nasopharyngitis, somnolence, and dry mouth (≥10% of patients). There were eight serious adverse events in seven patients and no deaths. No obvious duloxetine-related changes were observed in laboratory tests, vital signs, or electrocardiograms. The change from baseline in BPI-S average pain score was significant throughout the extension. Significant reductions in BPI-I, PGI-I, CGI-I, WOMAC, and SF36 scores were also maintained through 52 weeks. There were no substantial changes in range of motion or Kellgren-Lawrence grade.

Conclusion

In Japanese patients with chronic knee pain due to osteoarthritis, long-term treatment with duloxetine was well tolerated and associated with sustained improvements in pain and health-related quality of life without radiographic deterioration.

Serotonin and noradrenaline reuptake inhibitors (SNRIs) for fibromyalgia

BACKGROUND

Fibromyalgia is a clinically defined chronic condition of unknown etiology characterized by chronic widespread pain that often co-exists with sleep disturbances, cognitive dysfunction and fatigue. People with fibromyalgia often report high disability levels and poor quality of life. Drug therapy, for example, with serotonin and noradrenaline reuptake inhibitors (SNRIs), focuses on reducing key symptoms and improving quality of life. This review updates and extends the 2013 version of this systematic review.

OBJECTIVES

To assess the efficacy, tolerability and safety of serotonin and noradrenaline reuptake inhibitors (SNRIs) compared with placebo or other active drug(s) in the treatment of fibromyalgia in adults.

SEARCH METHODS

For this update we searched CENTRAL, MEDLINE, Embase, the US National Institutes of Health and the World Health Organization (WHO) International Clinical Trials Registry Platform for published and ongoing trials and examined the reference lists of reviewed articles, to 8 August 2017.

SELECTION CRITERIA

We selected randomized, controlled trials of any formulation of SNRIs against placebo or any other active treatment of fibromyalgia in adults.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data, examined study quality, and assessed risk of bias. For efficacy, we calculated the number needed to treat for an additional beneficial outcome (NNTB) for pain relief of 50% or greater and of 30% or greater, patient's global impression to be much or very much improved, dropout rates due to lack of efficacy, and the standardized mean differences (SMD) for fatigue, sleep problems, health-related quality of life, mean pain intensity, depression, anxiety, disability, sexual function, cognitive disturbances and tenderness. For tolerability we calculated number needed to treat for an additional harmful outcome (NNTH) for withdrawals due to adverse events and for nausea, insomnia and somnolence as specific adverse events. For safety we calculated NNTH for serious adverse events. We undertook meta-analysis using a random-effects model. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We added eight new studies with 1979 participants for a total of 18 included studies with 7903 participants. Seven studies investigated duloxetine and nine studies investigated milnacipran against placebo. One study compared desvenlafaxine with placebo and pregabalin. One study compared duloxetine with L-carnitine. The majority of studies were at unclear or high risk of bias in three to five domains.The quality of evidence of all comparisons of desvenlafaxine, duloxetine and milnacipran versus placebo in studies with a parallel design was low due to concerns about publication bias and indirectness, and very low for serious adverse events due to concerns about publication bias, imprecision and indirectness. The quality of evidence of all comparisons of duloxetine and desvenlafaxine with other active drugs was very low due to concerns about publication bias, imprecision and indirectness.Duloxetine and milnacipran had no clinically relevant benefit over placebo for pain relief of 50% or greater: 1274 of 4104 (31%) on duloxetine and milnacipran reported pain relief of 50% or greater compared to 591 of 2814 (21%) participants on placebo (risk difference (RD) 0.09, 95% confidence interval (CI) 0.07 to 0.11; NNTB 11, 95% CI 9 to 14). Duloxetine and milnacipran had a clinically relevant benefit over placebo in patient's global impression to be much or very much improved: 888 of 1710 (52%) on duloxetine and milnacipran (RD 0.19, 95% CI 0.12 to 0.26; NNTB 5, 95% CI 4 to 8) reported to be much or very much improved compared to 354 of 1208 (29%) of participants on placebo. Duloxetine and milnacipran had a clinically relevant benefit compared to placebo for pain relief of 30% or greater. RD was 0.10; 95% CI 0.08 to 0.12; NNTB 10, 95% CI 8 to 12. Duloxetine and milnacipran had no clinically relevant benefit for fatigue (SMD -0.13, 95% CI -0.18 to -0.08; NNTB 18, 95% CI 12 to 29), compared to placebo. There were no differences between either duloxetine or milnacipran and placebo in reducing sleep problems (SMD -0.07; 95 % CI -0.15 to 0.01). Duloxetine and milnacipran had no clinically relevant benefit compared to placebo in improving health-related quality of life (SMD -0.20, 95% CI -0.25 to -0.15; NNTB 11, 95% CI 8 to 14).There were 794 of 4166 (19%) participants on SNRIs who dropped out due to adverse events compared to 292 of 2863 (10%) of participants on placebo (RD 0.07, 95% CI 0.04 to 0.10; NNTH 14, 95% CI 10 to 25). There was no difference in serious adverse events between either duloxetine, milnacipran or desvenlafaxine and placebo (RD -0.00, 95% CI -0.01 to 0.00).There was no difference between desvenlafaxine and placebo in efficacy, tolerability and safety in one small trial.There was no difference between duloxetine and desvenlafaxine in efficacy, tolerability and safety in two trials with active comparators (L-carnitine, pregabalin).

AUTHORS' CONCLUSIONS

The update did not change the major findings of the previous review. Based on low- to very low-quality evidence, the SNRIs duloxetine and milnacipran provided no clinically relevant benefit over placebo in the frequency of pain relief of 50% or greater, but for patient's global impression to be much or very much improved and in the frequency of pain relief of 30% or greater there was a clinically relevant benefit. The SNRIs duloxetine and milnacipran provided no clinically relevant benefit over placebo in improving health-related quality of life and in reducing fatigue. Duloxetine and milnacipran did not significantly differ from placebo in reducing sleep problems. The dropout rates due to adverse events were higher for duloxetine and milnacipran than for placebo. On average, the potential benefits of duloxetine and milnacipran in fibromyalgia were outweighed by their potential harms. However, a minority of people with fibromyalgia might experience substantial symptom relief without clinically relevant adverse events with duloxetine or milnacipran.We did not find placebo-controlled studies with other SNRIs than desvenlafaxine, duloxetine and milnacipran.