The influence of age on salicylate pharmacokinetics in humans.

The pharmacokinetics of salicylate after a single oral solution dose of 600 mg of sodium salicylate were investigated in 22 male subjects. Subjects were healthy nonsmokers and were not taking any regular medication. The plasma concentration and urinary excretion of salicylic acid and its metabolite, salicyluric acid, as well as the urinary excretion of salicyl glucuronides were determined. Urinary recovery essentially accounted for the administered dose and was not influenced by age, nor was the apparent oral clearance of salicylic acid. Assuming no presystemic elimination, it could be concluded that systemic availability is unaffected by age. An increase in the apparent volume of distribution, Varea, and a decrease in the maximum plasma salicylic acid concentration with age were observed. Renal clearance of salicyluric acid decreased significantly with age and was found to correlate significantly with creatinine clearance. The authors conclude that age does not have a major influence on salicylate disposition in healthy adult men.