Metabolism of C14-Nicotinic Acid in Pig and Sheep

Abstract

Following the administration of 7-C¹⁴-nicotinic acid intramuscularly into a pig, 6 metabolites were observed in the urine. These were N-methylnicotinamide, nicotinuric acid, nicotinic acid, 4-pyridone, 2-pyridone, and nicotinamide. Of these, the 2-pyridone and 4-pyridone were the major persistent metabolies coming from the breakdown of the pyridine nucleotides. Three days after administering C¹⁴-nicotinic acid, only pyridine nucleotides and nicotinamide were noted in the pig tissues. In sheep urine, nicotinamide was the only persistent metabolite, whereas nicotinuric acid and nicotinic acid were the major excretion products during the first 8 hours after administration of the labeled nicotinic acid.