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Influence of Morphine and Naloxone on Pain Modulation in Rheumatoid Arthritis, Chronic Fatigue Syndrome/Fibromyalgia, and Controls: A Double‐Blind, Randomized, Placebo‐Controlled, Cross‐Over Study
Author(s) -
Hermans Linda,
Nijs Jo,
Calders Patrick,
De Clerck Luc,
Moorkens Greta,
Hans Guy,
Grosemans Sofie,
Roman De Mettelinge Tine,
Tuynman Joanna,
Meeus Mira
Publication year - 2018
Publication title -
pain practice
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 58
eISSN - 1533-2500
pISSN - 1530-7085
DOI - 10.1111/papr.12613
Subject(s) - medicine , placebo , fibromyalgia , summation , morphine , anesthesia , (+) naloxone , hyperalgesia , rheumatoid arthritis , opioid , chronic pain , nociception , physical therapy , stimulation , alternative medicine , receptor , pathology
Abstract Background Impaired pain inhibitory and enhanced pain facilitatory mechanisms are repeatedly reported in patients with central sensitization pain. However, the exact effects of frequently prescribed opioids on central pain modulation are still unknown. Methods A randomized, double‐blind, placebo‐controlled cross‐over trial was carried out. Ten chronic fatigue syndrome ( CFS )/fibromyalgia ( FM ) patients, 11 rheumatoid arthritis ( RA ) patients and 20 controls were randomly allocated to the experimental (10 mg morphine or 0.2 mg/mL Naloxone) and placebo (2 mL Aqua) group. Pressure pain thresholds ( PPT s) and temporal summation at the Trapezius and Quadriceps were assessed by algometry. Conditioned pain modulation ( CPM ) efficacy and deep tissue pain pressure were assessed by adding ischemic occlusion at the opposite upper arm. Results Deep tissue pain pressure was lower and temporal summation higher in CFS / FM ( P = 0.002 respectively P = 0.010) and RA patients ( P = 0.011 respectively P = 0.047) compared to controls at baseline. Morphine had only a positive effect on PPT s in both patient groups ( P time = 0.034). Accordingly, PPT s increased after placebo ( P time = 0.015), and no effects on the other pain parameters were objectified. There were no significant effects of naloxone nor nocebo on PPT , deep tissue pain, temporal summation or CPM in the control group. Conclusions This study revealed anti‐hyperalgesia effects of morphine in CFS / FM and RA patients. Nevertheless, these effects were comparable to placebo. Besides, neither morphine nor naloxone influenced deep tissue pain, temporal summation or CPM . Therefore, these results suggest that the opioid system is not dominant in (enhanced) bottom‐up sensitization (temporal summation) or (impaired) endogenous pain inhibition ( CPM ) in patients with CFS / FM or RA .