Salicylate kinetics in old age.

Salicylate kinetics were determined in 28 subjects 25 to 92 years old who received single, oral doses of sodium salicylate (1 gm/1.73 m2). The serum AUCinfinity of total salicylate did not correlate with age. There was a weak positive correlation between the AUCinfinity of free (unbound) drug and age, but there was no apparent difference between the AUCinfinity values of the 15 women and 13 men. Seven of the 16 subjects greater than 70 years of age cleared salicylate at about the same rate as the younger subjects. A comparison of these seven subjects with the nine greater than 70 years old who were slow eliminators of salicylate revealed that the latter group consisted of more bedridden patients and that these patients had somewhat lower serum albumin concentrations, but they did not differ from the more rapid eliminators with respect to serum creatinine or urea nitrogen levels, SGOT, average age, female/male ratio, and average body weight. The serum protein binding of salicylate decreased with increasing age, apparently due mainly to decreasing serum albumin concentrations.