Fate of Gentisic Acid in Man as Influenced by Alkalinization and Acidification

Abstract

The excretion of free and total gentisic acid with and without simultaneous alkalinization and acidification after admn. of Na gentisate or Na salicylate was detd. in a group of normal subjects. The recovery of gentisic acid and salicylate were similar, approximating 62 and 68%, respectively, of the administered drugs, and 84 and 88%, respectively, following alkalinization. Alkalinization increased the combined and free forms of gentisic acid eliminated but did not alter their relative proportions. The amt. of gentisic acid recovered from salicylate admn. was increased with alkalinization without alteration in the proportion of free to combined gentisic acid obtained with salicylate alone. Whereas the free gentisic acid represented approx. 42% of the total gentisic acid recovered when administered alone, the amt. of free gentisic acid obtained from salicylate admn. represented approx. 10% of the total gentisic acid. Acidification with dilute HCl, but not NH4Cl decreased the total excretion of gentisic acid at the expense of the combined, the free remaining unaltered. Acidification with both dilute HCl and NH4Cl decreased the total excretion of salicylate and the combined gentisic acid metabolite, the proportion of free to combined gentisic acid remaining unaltered.