Tuesday, June 4, 2019

Cornea nerve fiber state determines analgesic response to tapentadol in fibromyalgia patients without effective endogenous pain modulation

Abstract

Background

Tapentadol is a centrally acting analgesic with μ‐agonistic activity combined with noradrenaline reuptake inhibition. Its mechanism of action relies on improvement of descending pain inhibition. In the current study, tapentadol's ability to enhance conditioned pain modulation (CPM, an experimental measure of descending pain inhibition) was evaluated in fibromyalgia patients with absent or reduced CPM responses.

Methods

A total of 34 fibromyalgia patients completed this double‐blind trial. Patients were randomized to receive treatment with tapentadol sustained‐release or placebo for a 3‐month period with 1‐month follow‐up. At baseline the cornea nerve fiber state (CNFS) was quantified to determine the presence of nerve fiber pathology and assess its value in the prediction of the analgesic response.

Results

Tapentadol significantly increased CPM responses during treatment with an average increase from baseline of 20.5 ± 12.5% (tapentadol) versus 3.0 ± 11.2% (placebo; p = 0.042). No treatment effect was observed for the absolute pain scores, however analgesia responder rate analyses demonstrated a treatment effect in favor of tapentadol. Pain relief (a reduction in pain score ≥ 30%) was predicted by the presence of a normal CNFS (p = 0.035). Patients with an abnormal CNFS had no analgesic effect from tapentadol despite an increase in CPM.

Conclusions

In chronic pain patients with fibromyalgia, the increase in endogenous pain inhibition by tapentadol was translated into analgesia in patients with a normal CNFS. In those with abnormal CNFS, tapentadol treatment was without analgesic effect.

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from Wiley: European Journal of Pain: Table of Contents http://bit.ly/2ESaXPl
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