Nicotinamide: Difference between revisions

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{{Short description|Dietary supplement and medication}}

{{Infobox drug

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| pronounce          = {{IPAc-en|ˌ|n|aɪ|ə|ˈ|s|ɪ|n|ə|m|aɪ|d}}, {{IPAc-en|ˌ|n|ɪ|k|ə|ˈ|t|ɪ|n|ə|m|aɪ|d}}

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| legal_AU          = <!-- S2, S3, S4, S5, S6, S7, S8, S9 or Unscheduled-->

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| legal_status      = <!--For countries not listed above-->

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| bioavailability    =  

| excretion          =

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| CAS_number        = 98-92-0

| synonyms          = NAM, 3-pyridinecarboxamide<br />niacinamide<br />nicotinic acid amide<br />vitamin PP<br />nicotinic amide<br />vitamin B₃

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| IUPAC_name        = pyridine-3-carboxamide

}}

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'''Niacinamide''' or '''nicotinamide''' is a form of [[vitamin B3|vitamin B₃]] found in food and used as a [[dietary supplement]] and medication. As a supplement, it is used by mouth to prevent and treat [[pellagra]] (niacin deficiency). While [[nicotinic acid]] (niacin) may be used for this purpose, niacinamide has the benefit of not causing [[Flushing (physiology)|skin flushing]]. 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 vitamins|water-soluble vitamin]]. Niacinamide is the supplement name, while nicotinamide is the scientific name.

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Side effects are minimal. At high doses, [[liver problems]] may occur. Normal amounts are safe for use during [[pregnancy]]. Niacinamide is in the [[vitamin B]] family of medications, specifically the [[vitamin B3 complex|vitamin B₃ complex]]. It is an [[amide]] of nicotinic acid. Foods that contain niacinamide include [[yeast]], [[meat]], milk, and [[green vegetables]].

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Niacinamide was discovered between 1935 and 1937. It is on the [[WHO Model List of Essential Medicines|World Health Organization's List of Essential Medicines]]. Niacinamide is available as a [[generic medication]] and [[over the counter]]. Commercially, niacinamide is made from either [[Niacin (substance)|nicotinic acid]] (niacin) or [[nicotinonitrile]]. In some countries, [[food grains|grains]] have niacinamide added to them.

Niacinamide is the preferred treatment for [[pellagra]], caused by niacin deficiency.

Niacinamide [[Cream (pharmaceutical)|cream]] is used as a treatment for [[acne]].

Niacinamide increases the biosynthesis of [[ceramide]]s in human [[keratinocyte]]s in vitro and improves the epidermal permeability barrier in vivo. The application of 2% topical niacinamide for 2 and 4 weeks has been found to be effective in lowering the [[Sebaceous gland|sebum]] excretion rate. Niacinamide has been shown to prevent ''[[Cutibacterium acnes]]''-induced activation of [[TLR2|toll-like receptor 2]], which ultimately results in the down-regulation of pro-inflammatory [[Interleukin 8|interleukin-8]] production.

Niacinamide at doses of 500 to 1000{{nbsp}}mg a day decreases the risk of [[skin cancer]]s, other than [[melanoma]], in those at high risk.

Niacinamide has minimal side effects. At very high doses above 3g/ day acute [[liver toxicity]] has been documented in at least one case. Normal doses are safe during [[pregnancy]].

The structure of nicotinamide consists of a [[pyridine]] ring to which a [[primary amide]] group is attached in the [[arene substitution pattern|''meta'']] position. It is an [[amide]] of [[nicotinic acid]]. As an [[aromatic compound]], it undergoes [[electrophilic aromatic substitution|electrophilic substitution]] reactions and transformations of its two [[functional group]]s. Examples of these reactions reported in ''[[Organic Syntheses]]'' include the preparation of [[2-chloronicotinonitrile]] by a two-step process via the [[N-oxide|''N''-oxide]],

:[[File:Nicotinamide to 2-chloronicotinonitrile.png|500px]]

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]].

[[File:Nicotinamide highlighted in NAD+.svg|thumb|right|NAD⁺, the oxidized form of [[nicotinamide adenine dinucleotide|NADH]], contains the nicotinamide [[moiety (chemistry)|moiety]] (highlighted in red)]]

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.

[[File:NAD+ Oxidation and Reduction.png|thumb|upright=1.3|The active Nicotinamide group on the molecule NAD⁺ undergoes oxidation in many metabolic pathways.]]

Nicotinamide, as a part of the cofactor [[nicotinamide adenine dinucleotide]] (NADH / NAD⁺) is crucial to life. In cells, nicotinamide is incorporated into NAD⁺ and [[nicotinamide adenine dinucleotide phosphate]] (NADP⁺). NAD⁺ and NADP⁺ are [[Cofactor (biochemistry)|cofactor]]s in a wide variety of enzymatic [[redox|oxidation-reduction]] reactions, most notably [[glycolysis]], the [[citric acid cycle]], and the [[electron transport chain]]. 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⁺. This method of creation of NAD⁺ is called a [[Salvage Pathway|salvage pathway]]. However, the human body can produce NAD⁺ from the amino acid [[tryptophan]] and niacin without our ingestion of nicotinamide.

NAD⁺ 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⁺, the nitrogen in the aromatic nicotinamide ring is covalently bonded to adenine dinucleotide. The formal charge on the nitrogen is stabilized by the shared electrons of the other carbon atoms in the aromatic ring. When a hydride atom is added onto NAD⁺ to form NADH, the molecule loses its aromaticity, and therefore a good amount of stability. This higher energy product later releases its energy with the release of a hydride, and in the case of the electron transport chain, it assists in forming [[adenosine triphosphate]].

When one mole of NADH is oxidized, 158.2{{nbsp}}kJ of energy will be released.

Nicotinamide occurs as a component of a variety of biological systems, including within the [[vitamin B]] family and specifically the [[vitamin B3 complex|vitamin B₃ complex]]. It is also a critically important part of the structures of [[nicotinamide adenine dinucleotide|NADH and NAD⁺]], where the ''N''-substituted aromatic ring in the oxidised NAD⁺ form undergoes reduction with hydride attack to form NADH. The [[Nicotinamide adenine dinucleotide phosphate|NADPH/NADP⁺]] structures have the same ring, and are involved in similar biochemical reactions.

Nicotinamide can be methylated in the liver to biologically active [[1-Methylnicotinamide]] when there are sufficient methyl donors.

Niacinamide occurs in trace amounts mainly in meat, fish, nuts, and mushrooms, as well as to a lesser extent in some vegetables. It is commonly added to cereals and other foods. Many multivitamins contain 20–30{{nbsp}}mg of vitamin B₃ and it is also available in higher doses.

* [[British Pharmacopoeia]]

* [[Japanese Pharmacopoeia]]

A 2015 trial found niacinamide to reduce the rate of new nonmelanoma skin cancers and actinic keratoses in a group of people at high risk for the conditions.

Niacinamide has been investigated for many additional disorders, including treatment of [[bullous pemphigoid]] nonmelanoma skin cancers.

Niacinamide may be beneficial in treating psoriasis.

There is tentative evidence for a potential role of niacinamide in treating acne, rosacea, autoimmune blistering disorders, ageing skin, and atopic dermatitis. Niacinamide also inhibits poly(ADP-ribose) [[polymerase]]s ([[PARP1|PARP-1]]), enzymes involved in the rejoining of DNA strand breaks induced by radiation or chemotherapy. ARCON (accelerated radiotherapy plus carbogen inhalation and nicotinamide) has been studied in cancer.

Research has suggested niacinamide may play a role in the treatment of [[HIV]].

{{Vitamins}}

{{Estrogen receptor modulators}}

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{{二次利用|date=23 March 2024}}

[[Category:Nicotinamides| ]]