The purpose of this study is to determine whether milnacipran reduces widespread, non-joint pain in patients with rheumatoid arthritis (RA). The investigators will conduct a double-blind randomized crossover trial in subjects with RA to test the hypothesis that milnacipran improves widespread, non-joint pain. The investigators will also use data from the trial to determine whether response to milnacipran is associated with pain-modulating mechanisms from the central nervous system. The investigators hypothesize that response to milnacipran will be greater among patients with impaired central pain mechanisms than among patients with intact central pain modulating mechanisms.
Despite the development of effective medications to treat inflammation, pain remains a priority for rheumatoid arthritis (RA) patients. The pain that persists despite anti-inflammatory treatment is usually widespread and non-articular; it may lead to diminished quality of life and high medical, psychological and social costs. To develop better treatments for pain and prevent disability, it is critical to obtain a better understanding of widespread, non-joint pain in RA. Milnacipran is a selective serotonin-norepinephrine reuptake inhibitor (SNRI). No studies have examined the effect of SNRIs on pain in RA. However, several studies have examined the role of SNRIs in fibromyalgia and related pain conditions. Treatment with milnacipran has been associated with improvements in clinical pain severity in Phase 2 and Phase 3 randomized placebo-controlled trials of fibromyalgia patients. In animal models, milnacipran appears to moderate the pain-inducing effects of inflammation and central sensitization. Thus milnacipran may be an ideal drug to treat pain in RA. A clinical trial of an SNRI in the treatment of widespread, non-joint pain in RA will provide more information regarding pain mechanisms and may lead to more targeted, effective ways of treating pain in RA.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
49
Milnacipran comes in 50 mg tablets and is taken orally. Participants will gradually be increased to a target dose of 50 mg twice daily.
Brigham and Women's Hospital
Boston, Massachusetts, United States
Brief Pain Inventory (BPI) Change
A measure of change in scores on the BPI short form, a "24-hr average pain" item, from baseline to 6 weeks, The BPI short form scores ranges from 0-10, with 10 being the worst pain.
Time frame: Baseline to 6 weeks
Change in Conditioned Pain Modulation (CPM)
CPM is defined as the difference between pain threshold A (measured after a conditioning stimulus activates pathways that inhibit pain) and pain threshold B (measured before the conditioning stimulus is applied). The conditioning stimulus was immersion of the hand in a cold water bath. Pressure pain threshold was assessed at the trapezius muscle initially. Subjects were then instructed to immerse their hand in a water bath for 30 seconds. At 20 seconds, pressure pain threshold at the trapezius was assessed again. We defined the magnitude of subjects' CPM as the difference in pressure pain threshold between baseline and 20 seconds after cold water immersion. This difference was compared to that measured at 6 weeks. The scale for the difference in CPM ranged from 0-11 kg/cm\^2, with 0 indicating no change in CPM between 6 weeks and baseline and 11 indicating the maximum possible change. A greater change in CPM between baseline and 6 weeks is indicative of improvements in CPM.
Time frame: Baseline to 6 weeks
Symptom Intensity Scale (SIS)
A measure of the change in SIS score from baseline to 6 weeks. The SIS score ranges from 0-9.75, with high scores being worse indicating more widespread pain and fatigue.
Time frame: Baseline to 6 weeks
Thumbnail Pain Threshold
A measure of the change in thumbnail pain threshold from baseline to 6 weeks. Thumbnail pain threshold was determined by applying pressure to a subjectt's thumbnail until the subject felt pain. The difference between the average thumbnail pain threshold (an average for the right and left thumbs) at baseline was compared to that at 6 months. Pain threshold was measured in kg/cm\^2. The difference in threshold could range from 0-11 kg/cm\^2. A higher difference between thresholds indicates improved pain sensitivity.
Time frame: Baseline to 6 weeks
Trapezius Pain Threshold
A measure of the change in trapezius pain threshold from baseline to 6 weeks. Trapezius pain threshold was determined by applying pressure to a subject's trapezius muscle until the subject felt pain. The difference between the average trapezius pain threshold (an average for the right and left trapezii) at baseline was compared to that at 6 months. Pain threshold was measured in kg/cm\^2. The difference in threshold could range from 0-11 kg/cm\^2. A higher difference between thresholds indicates improved pain sensitivity.
Time frame: Baseline to 6 weeks
Wrist Pain Threshold
A measure of the change in wrist pain threshold from baseline to 6 weeks. Wrist pain threshold was determined by applying pressure to a subject's wrist until the subject felt pain. The difference between the average wrist pain threshold (an average for the right and left wrists) at baseline was compared to that at 6 months. Pain threshold was measured in kg/cm\^2. The difference in threshold could range from 0-11 kg/cm\^2. A higher difference between thresholds indicates improved pain sensitivity.
Time frame: Baseline to 6 weeks
Knee Pain Threshold
A measure of the change in knee pain threshold from baseline to 6 weeks. Knee pain threshold was determined by applying pressure to a subject's knee until the subject felt pain. The difference between the average knee pain threshold (an average for the right and left knees) at baseline was compared to that at 6 months. Pain threshold was measured in kg/cm\^2. The difference in threshold could range from 0-11 kg/cm\^2. A higher difference between thresholds indicates improved pain sensitivity.
Time frame: Baseline to 6 weeks
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