Nicotinamide

Nicotinamide, also known as niacinamide and nicotinic acid amide, is the amide of nicotinic acid (vitamin B3 / niacin). Nicotinamide is a water-soluble vitamin and is part of the vitamin B group. Nicotinic acid, also known as niacin, is converted to nicotinamide in vivo, and, though the two are identical in their vitamin functions, nicotinamide does not have the same pharmacologic and toxic effects of niacin, which occur incidental to niacin's conversion. Thus nicotinamide does not reduce cholesterol or cause flushing, although nicotinamide may be toxic to the liver at doses exceeding 3 g/day for adults. In cells, niacin is incorporated into nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), although the pathways for nicotinamide and nicotinic acid are very similar. NAD+ and NADP+ are coenzymes in a wide variety of enzymatic oxidation-reduction reactions.

Use in medicine
Nicotinamide has demonstrated anti-inflammatory actions that may be of benefit to patients with inflammatory skin conditions. These conditions include acne vulgaris, and the compound can suppress antigen-induced, lymphocytic transformation and inhibit 3'-5' cyclic AMP phosphodiesterase. Nicotinamide has demonstrated the ability to block the inflammatory actions of iodides known to precipitate or exacerbate inflammatory acne.

Nicomide is the name of an acne medication and, in its vitamin supplement form, the most predominant ingredient is 750 mg of nicotinamide, based on this area of research. Also, it is used topically as a 4% or 5% gel or cream - as effective as topical 1% clindamycin (8-week double-blind trial) performed at the New York University College of Medicine. Nicotinamide acne treatment is also available as Nicotinamide pads and cream.

Animal studies show that nicotinamide has anti-anxiety (anxiolytic) properties. It may work in a way similar to benzodiazepines.

Nicotinamide lacks the vasodilator, gastrointestinal, hepatic, and hypolipidemic actions of nicotinic acid. As such, nicotinamide has not been shown to produce the flushing, itching, and burning sensations of the skin as is commonly seen when large doses of nicotinic acid are administered orally. High-dose nicotinamide should still, however, be considered as a drug with toxic potential at adult doses in excess of 3 gm/day and unsupervised use should be discouraged. In overall, it rarely causes side effects, and is considered generally safe as a food additive, and as a component in cosmetics and medication.

Nicotinamide is produced by the aqueous aminolysis of 3-cyanopyridine (nicotinonitrile) and subsequent crystallization.

Nicotinamide is an activator of sirtuins (but inhibits at higher doses) and has been reported to restore cognition in Alzheimer's disease transgenic mice. A safety study of  niacinamide for the treatment of Alzheimer's disease is currently underway at the University of California, Irvine.

Nicotinamide has been reported to increase the endurance of mice.

Nicotinamide prevents immunosuppression caused by UVA and UVB radiation, and could be added to sunscreen.

Nicotinamide has been reported to be an effective skin whitener in topical application.

Niacinamide acts as a chemo- and radio-sensitizing agent by enhancing tumor blood flow, thereby reducing tumor hypoxia. Niacinamide also inhibits poly(ADP-ribose) polymerases (PARP-1), enzymes involved in the rejoining of DNA strand breaks induced by radiation or chemotherapy. PARP-1 appears to be an important target for triple negative breast cancers because the cells are sensitive to inhibition of PARP-1. Niacinamide is also used by some patients in combination with intravenous vitamin C therapy for cancer.

Compendial status

 * British Pharmacopoeia
 * Japanese Pharmacopoeia