A combination of anticonvulsant pregabalin and the antidepressant duloxetine may help improve pain relief, physical function, and overall quality of life in patients with fibromyalgia. That’s according to a the first double-blind randomized controlled trial to compare the combination for the treatment of fibromyalgia. The study was conducted by researchers in Canada and published in the journal Pain.
A total of 39 patients received maximally tolerated doses (MTD) of placebo, pregabalin, duloxetine and pregabalin-duloxetine combination for 6 weeks. The primary outcome was average pain intensity over the past 24 hours, rated each morning and averaged over 7 days at MTD. Secondary outcomes included worst pain intensity over the past 24 hours and average nocturnal pain intensity during sleeping hours, both rated each morning upon arising and averaged over 7 days at MTD.
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Pain with the combination of pregabalin-duloxetine was found to be lower than with placebo (p<0.001) and pregabalin alone (p<0.001). Pain with duloxetine was lower than placebo (p<0.001) and pregabalin alone (p=0.003). The trends which displayed superiority of the combination over duloxetine monotherapy failed to reach significance, though superiority of the combination to duloxetine cannot be ruled out, as the interim analysis indicted a conditional probability of 70% for a significant difference and sample number was limited.
Interestingly, the comparison of the combination to duloxetine resulted in a p-value of 0.09. Secondary analyses of percentage change indicated greater reduction (percentage change ± SEM) with combination (27.5% ± 6.0) vs. pregabalin (1.4% ± 5.6, p=0.01) and placebo (-7.1% ± 5.5, p=0.003).
Concerning the secondary outcomes, patients reported pain relief at MTD of 18.4% on placebo, 38.5% on pregabalin, 41.7% on duloxetine and 67.7% on the pregabalin-duloxetine combination. The worst pain experienced with the combination was lower than both placebo and pregabalin. Pain interference with enjoyment of life was also found to be significantly lower for the combination and duloxetine use vs. placebo.
Although the benefits of this combination may come with increased risk of drowsiness, the authors conclude that “combining pregabalin with duloxetine for fibromyalgia improves multiple clinical outcomes versus monotherapy.” Further research should be done to compare other potential combinations for the treatment of fibromyalgia
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