<!-- Definition and medical uses -->
Nicotinamide (INN, BAN ) or niacinamide (USAN ) (IUPAC name: 3-pyridinecarboxoamide) is a form of vitamin B<sub>3</sub> found in food and used as a dietary supplement and medication. As a supplement, it is used orally (swallowed by mouth) to prevent and treat pellagra (niacin deficiency). As a cream, it is used to treat acne, and has been observed in clinical studies to improve the appearance of aging skin by reducing hyperpigmentation and redness. It is a water-soluble vitamin.
Clinical trials have show promise in eye health, in this B3 form, it has shown promise in protecting eye health, particularly in the context of glaucoma. It is believed to support the health of retinal ganglion cells and may help protect against glaucoma-related damage. Nicotinamide has been studied for its potential neuroprotective effects. While some clinical trials have demonstrated improvements in visual fields and retinal function, it is not yet approved for the treatment of glaucoma. The use of nicotinamide should be approached with caution, especially at high doses, due to the risk of liver injury. Ongoing research continues to explore the full potential of nicotinamide in eye protection and its role in managing eye conditions.
<!-- Side effects and mechanism -->
Side effects are minimal. At high doses, liver problems may occur. Nicotinamide is in the vitamin B family of medications, specifically the vitamin B<sub>3</sub> complex. It is an amide of nicotinic acid. Foods that contain nicotinamide include yeast, meat, milk, and green vegetables.
<!-- History and culture -->
Nicotinamide was discovered between 1935 and 1937. Nicotinamide is available as a generic medication and over the counter.
Extraterrestrial nicotinamide has been found in carbonaceous chondrite meteorites.
Medical uses
Niacin deficiency
Nicotinamide is the preferred treatment for pellagra, caused by niacin deficiency.
Nicotinamide increases the biosynthesis of ceramides in human keratinocytes in vitro and improves the epidermal permeability barrier in vivo. The application of 2% topical nicotinamide for 2 and 4 weeks is effective in lowering the sebum excretion rate. Nicotinamide has been shown to prevent Cutibacterium acnes-induced activation of toll-like receptor 2, which ultimately results in the down-regulation of pro-inflammatory interleukin-8 production.
Skin cancer
Nicotinamide at doses of 500 to 1000mg a day decreases the risk of skin cancers, other than melanoma, in those at high risk.
Eye health
Nicotinamide has shown promise in slowing vision loss from glaucoma.
Side effects
Nicotinamide has minimal side effects.
:500px|class=skin-invert-image
from nicotinonitrile by reaction with phosphorus pentoxide, and from 3-aminopyridine by reaction with a solution of sodium hypobromite, prepared in situ from bromine and sodium hydroxide.
thumb|right|class=skin-invert-image|NAD<sup>+</sup>, the oxidized form of [[nicotinamide adenine dinucleotide|NADH, contains the nicotinamide moiety (highlighted in red)]]
Industrial production
The hydrolysis of nicotinonitrile is catalysed by the enzyme nitrile hydratase from Rhodococcus rhodochrous J1, producing 3500 tons per annum of nicotinamide for use in animal feed. The enzyme allows for a more selective synthesis as further hydrolysis of the amide to nicotinic acid is avoided. Nicotinamide can also be made from nicotinic acid. According to Ullmann's Encyclopedia of Industrial Chemistry, worldwide 31,000 tons of nicotinamide were sold in 2014. If humans ingest nicotinamide, it will likely undergo a series of reactions that transform it into NAD, which can then undergo a transformation to form NADP<sup>+</sup>. This method of creation of NAD<sup>+</sup> is called a salvage pathway. However, the human body can produce NAD<sup>+</sup> from the amino acid tryptophan and niacin without ingestion of nicotinamide.
NAD<sup>+</sup> acts as an electron carrier that mediates the interconversion of energy between nutrients and the cell's energy currency, adenosine triphosphate (ATP). In oxidation-reduction reactions, the active part of the cofactor is the nicotinamide. In NAD<sup>+</sup>, the nitrogen in the aromatic nicotinamide ring is covalently bonded to adenine dinucleotide. The shared electrons of the other carbon atoms in the aromatic ring stabilize the formal charge on the nitrogen. When a hydride atom is added onto NAD<sup>+</sup> to form NADH, the molecule loses its aromaticity and therefore a good amount of stability. This higher-energy product later releases its energy by donating a hydride, and in the case of the electron transport chain, it assists in forming adenosine triphosphate.
When one mole of NADH is oxidized, it releases 158.2kJ of energy. It is commonly added to cereals and other foods. Many multivitamins contain 20–30 of vitamin B<sub>3</sub>, and it is also available in higher doses.
Compendial status
- British Pharmacopoeia
- Japanese Pharmacopoeia
Research
A 2015 trial found nicotinamide to reduce the rate of new nonmelanoma skin cancers and actinic keratoses in a group of people at high risk for the conditions.
Nicotinamide has been investigated for many additional disorders, including treatment of bullous pemphigoid and nonmelanoma skin cancers.
Nicotinamide may be beneficial in treating psoriasis.
There is tentative evidence for a potential role of nicotinamide in treating acne, rosacea, autoimmune blistering disorders, ageing skin, and atopic dermatitis. ARCON (accelerated radiotherapy plus carbogen inhalation and nicotinamide) has been studied in cancer.
Research has suggested nicotinamide may play a role in the treatment of HIV.
Extra-terrestrial occurrence
Extra-terrestrial nicotinamide has been found in carbonaceous chondrite meteorites.
{| class="wikitable"
|+ Vitamin B3 vitamers from extra-terrestrial sources
|-
! Meteorite !! Nicotinic acid !! Nicotinamide
|-
| Orgueil || 715 ppb || 214 ppb
|-
| Murray || 626 ppb || 65 ppb
|-
| Murchison || 2.4 nmol/g 190 ppb || 16 ppb
|-
| Tagish Lake || 108 ppb || 5 ppb
|}