Background & Aims
Acetaminophen is suggested to activate the descending pain inhibitory mechanisms. Conditioned pain modulation (CPM), temporal summation of pain (TSP), and offset analgesia (OA) reflect different aspects of central pain modulatory pathways. However, the effect of acetaminophen on these mechanisms remains unclear. The aim was to investigate the effect of acetaminophen on CPM, TSP, and OA. In addition, the effect of non-steroidal anti-inflammatory drugs (NSAIDs; loxoprofen sodium hydrate) on CPM, TSP, and OA was evaluated.
Methods
Thirty healthy volunteers (16 males, age; 29.5[27.3–37.3]) were recruited. Pressure pain threshold (PPT) was measured with and without a thermal conditioning stimulus (CS). CPM effect was calculated as (PPT with CS/PPT without CS ? 1) × 100 (%). TSP ratio was evaluated by pin prick and calculated as; mean VAS scores from the 8th to the 10th stimulus/mean VAS scores from the first to the fourth stimulus. OA was induced by three-heat-stimulus train (T1–T2–T3) and was calculated as (maximum VAS score for T2) – (minimum VAS score for T3). CPM, TSP and OA were evaluated before (CPMpre, TSPpre or OApre) and 30 minutes after 1000mg of oral acetaminophen administration (test session 1), 120mg of oral loxoprofen sodium hydrate administration (test session 2), or lactose administration (control session). The relationships between pre administration and increment by these drugs in CPM, TSP and OA were analyzed with Spearman correlation coefficient (statistical significance: p<0.05).
Results
In test session 1 (acetaminophen administration), significant negative correlations were observed between the CPMpre and increment in CPM (R=-0.7216, p=0.0005), the TSPpre and increment in TSP (R=-0.8293, p<0.00001), and the OApre and increment in OA (R=-0.6246, p=0.0004). In test session 2 (loxoprofen sodium hydrate) and control session (lactose administration), there were no significant correlation between the CPMpre and increment in CPM, the TSPpre and increment in TSP, and the OApre and increment in OA (p>0.05).
Conclusions
Acetaminophen might activate central pain modulatory pathways which are featured by CPM, TSP and OA. There was no effect of NSAIDs on CPM, TSP, and OA.
References
Oono Y, Kono R, Kiyohara Y, Takagi S, Ide Y, Nagasaka H, Kohase H. Photobiomodulation enhanced endogenous pain modulation in healthy volunteers. Lasers Med Sci. 2022;38(1):16.
Presenting Author
Yuka Oono
Poster Authors
Yuka Oono
DDS, PhD
Division of Dental Anesthesiology, Meikai University School of Dentistry
Lead Author
Ryoko Kono
DDS
Division of Dental Anesthesiology, Meikai University School of Dentistry
Lead Author
Shinnosuke Ando
DDS
Division of Dental Anesthesiology, Meikai University School of Dentistry
Lead Author
Saori Takagi
DDS
Division of Dental Anesthesiology, Meikai University School of Dentistry
Lead Author
Hiroshi Nagasaka
MD
Department of Anesthesiology, Saitama Medical University, Faculty of Medicine
Lead Author
Tsutomu Mieda
MD
Department of Anesthesiology, Saitama Medical University, Faculty of Medicine
Lead Author
Lars Arendt-Nielsen
PhD
Aalborg University
Lead Author
Hikaru Kohase
school of dentistry, Meikai University
Lead Author
Topics
- Assessment and Diagnosis