Toxicity Profile for Niacinamide (1998)

Abstract

Niacinamide and its parent acid (nicotinic acid) are required for the formation of essential coenzymes and are present naturally in a range of foods. In acute studies, niacinamide demonstrated low toxicity in rodents treated orally and in rabbits treated by the dermal route. High therapeutic doses given orally to patients have been associated with a range of symptoms including, possibly, effects on the liver and skin; repeated administration to rodents by the oral or injection routes also produced mild liver effects. Limited studies found no adverse reproductive effects when pregnant mice were treated orally or by injection. There was no convincing evidence of carcinogenic potential in limited oral studies in mice and rats. There is limited evidence of niacinamide's ability to increase the tumour yield of known carcinogens in rodents, but it inhibits the action of many other carcinogens. Chromosomal effects were not found in mice treated by injection, but were reported in human and hamster cells treated in culture. Niacinamide was described as weakly mutagenic in one Ames bacterial test, but gave no evidence of mutagenicity in other Ames tests. The amide produced eye irritation in rabbits and induced skin sensitization in guinea pigs, whilst nicotinic acid has given some indication of skin sensitization potential in humans.