The effect of acetaminophen on post‐exercise IL‐6 levels in human Achilles peritendinous tissue

Abstract

Traditionally viewed as having weak anti-inflammatory activity in vivo, acetaminophen (APAP) has recently been shown, in humans, to inhibit cyclooxygenase-2 a key mediator of inflammation. We evaluated the effects of APAP on the inflammatory mediator IL-6 in human Achilles peritendinous tissue after treadmill exercise. Subjects were randomly assigned to a placebo (n=8, 26±1 y) or APAP (n=8, 25±1 y) group. After basal measurements, subjects ran for 1 hour (75–85% maximum heart rate, 3% grade). Microdialysis catheters were placed ventral to the Achilles tendon. Drug (1000 mg APAP) was administered in a double-blind manner 1 hour prior to microdialysis sampling and the peritendinous concentration of APAP was determined via HPLC. Dialysate collected from 2–6 hours post-exercise was assayed for IL-6 by enzyme immunoassay. IL-6 increased with exercise in both groups (p<0.05) but the post-exercise response in the APAP was 55% lower (p<0.05) than the placebo group (Placebo: 3856±799 vs APAP: 1720±270 pg•ml−1) when compared at peak peritendinous levels of APAP (3.87±0.67 μg•ml−1). The mean area-under-the-curve for IL-6 was 32% lower in the APAP group (p>0.05). The IL-6 response to exercise was generally lower in the group consuming APAP but additional subjects are needed to evaluate this potential difference. Study of additional inflammatory mediators is warranted. American College of Foot and Ankle Surgeons, American Podiatric Medical Students' Association, Midwestern University