Pharmacokinetics and pharmacodynamics in copper deficiency. I. Antiinflammatory activity of aspirin

The effect of nutritional copper (Cu) deficiency on the antiinflammatory activity and pharmacokinetics of aspirin (ASA) was investigated in rats. Male, weanling Sprague-Dawley rats were fed either a Cu-deficient (CuD) or Cu-sufficient (CuS) diet for 49-50 d. The antiinflammatory activity of ASA was studied using the carrageenan-induced paw edema (CPE) test. ANOVA analyses of edema volumes at 2, 3, 4, 5, and 21 h postcarrageenan indicated significant differences between groups. The percent inhibition of edema due to ASA treatment in CuS was lower than that in CuD rats at 5 h, AUC5h, and AUC21h. ASA was found to be significantly more effective in inhibiting the CPE in CuD rats when compared to the CuS rats. Thus, we hypothesized that the increase in ASA's antiinflammatory activity in CuD rats was a result of a decrement in its elimination during nutritional Cu deficiency. The elimination of ASA in CuD and CuS rats was studied using an iv dose of 200 mg/kg. Concentrations of ASA and salicylic acid (SA) were determined in blood; whereas the concentrations of SA, salicylic phenol-glucuronide (SPG), and salicyluric acid (SUA) were determined in urine by HPLC. The results of the pharmacokinetic analyses from blood and urinary data indicated no significant differences in the disposition of ASA between CuD and CuS rats. For instance, the total body clearance for ASA (mean +/- SD, mL/min/kg) was 37.9 +/- 9.4 and 38.5 +/- 13.9 (p > 0.05); and the volume of distribution (Vd) for ASA (mean +/- SD, mL/kg) was 385.5 +/- 110.3 and 397.1.1 +/- 137.9 (p > 0.05) for CuD and CuS groups, respectively. Thus, contrary to our hypothesis, the enhanced antiinflammatory activity of ASA in CuD rats does not appear to be mediated via a decrement in the elimination of the drug. In addition, plasma ASA-esterase activity was found to be independent of Cu nutritional status.