The relative potencies of some substituted salicylic acids as metabolic stimulants in the intact rat.

The effects of eighteen substituted benzoic acids on the rate of oxygen consumption have been studied in rats. 2:3-Dihydroxybenzoic acid, phthalic acid and 6-methylsalicylic acid were, at the doses used, inactive; m- and p-hydroxybenzoic acid, 2:4-, 2:5-, 2:6-, 3:4-, and 3:5-dihydroxybenzoic acid, o-aminobenzoic acid, salicyluric acid, salicylamide and 5-aminosalicylic acid decreased the rate of oxygen consumption. Only salicylic acid and o-, m- and p-cresotic acid (3-, 4- and 5-methylsalicylic acid respectively) increased the rate of oxygen consumption. Molar potency ratios of the cresotic acids as metabolic stimulants relative to salicylic acid were determined; o-cresotic acid was the most powerful with a ratio of 2.61, m- and pcresotic acid had values of 1.78 and 1.89 respectively. Two possible explanations of the higher potencies of the cresotic acids were considered. No difference in the primary action of the drug was established by determining the effect on rate of oxygen consumption of a mixture of o-cresotic and salicylic acids. An alternative possibility was that the rates of detoxication and excretion of the cresotic acids differed among themselves and from salicylic acid. No such differences were found.