Excretion of N 1 -Methylnicotinamide and the 6-Pyridone of N 1 -Methylnicotinamide in Urine of Human Subjects. ∗

Abstract

Summary

Essentially normal subjects maintained for short periods on diets low in nicotinamide and tryptophan excrete approximately 3 mg of N¹-Me and 5 mg of pyridone per day. Following an oral 50 mg test dose of nicotinamide; the average increase in excretion of N¹-Me is 5.5 mg and that of pyridone, 23.4 mg. The excretion of N¹-Me following the test dose rises rapidly during the first 4 hours and decreases to basal levels within 24 hours; pyridone is excreted more slowly the first few hours but appears in large amounts later in the day. After graded doses of nicotinamide, the excretion of pyridone increases more rapidly than does that of N¹-Me. In subjects with pellagra, the excretion of these metabolites is lower both on standard diets and following administration of small doses of nicotinamide. These data suggest procedures that may be of use in evaluating niacin nutrition.