Effects of acetaminophen and ibuprofen on renal function in the stressed kidney

Exercise, salt restriction, and/or dehydration causes transient reductions in renal function that may be buffered by vasodilatory prostaglandins (PGs) . Over-the-counter (OTC) analgesics have the potential to alter renal hemod ynamics by inhibiting renal PGs. Therefore, we tested the renal effects of the maximal recommended dose of acetaminophen (Acet, 4 g/day) and ibuprofen (Ibu, 1.2 g;/day) vs. a placebo (Pl) in humans subjected to progressive re nal stresses. After baseline measurements, 12 fit young (25 +/- 1 yr) men a nd women underwent 3 days of a low (10 meq/day)-sodium diet while taking on e of the drugs or Pl (crossover design). Day 4 involved dehydration (-1.6% body wt) followed by 45 min of treadmill exercise (65% maximal O-2 uptake) in the heat (36 degrees C). These combined stressors caused dramatic decrea ses in effective renal plasma flow, glomerular filtration rate (GFR), and s odium excretion. Baseline GFR (range: 118-123 ml/min) decreased to 78 +/- 4 , 73 +/- 5, and 82 +/- 5 ml/min postexercise in the Acet, Ibu, and Pl trial s, respectively, with a significantly greater decrease in GFR in the Ibu tr ial (P < 0.05 vs. Pl). OTC Ibu has small but statistically significant effe cts on GFR during exercise in a sodium- and volume-depleted state; OTC Acet was associated with no such effects.