2883 Nicotinic acid Nicotinic acid, also known as niacin or vitamin B3, is a water-soluble vitamin whose derivatives such as NADH, NAD, NAD+, and NADP play essential roles in energy metabolism in the living cell and DNA repair. The designation vitamin B3 also includes the amide form, nicotinamide or niacinamide. Severe lack of niacin causes the deficiency disease pellagra, whereas a mild deficiency slows down the metabolism decreasing cold tolerance. The recommended daily allowance of niacin is 2-12 mg a day for children, 14 mg a day for women, 16 mg a day for men, and 18 mg a day for pregnant or breast-feeding women. It is found in various animal and plant tissues and has pellagra-curative, vasodilating, and antilipemic properties. The liver can synthesize niacin from the essential amino acid tryptophan (see below), but the synthesis is extremely slow and requires vitamin B6; 60 mg of tryptophan are required to make one milligram of niacin. Bacteria in the gut may also perform the conversion but are inefficient. 59-67-6 938 C6H5NO2 123.032030 White powder. 236.6°C 1.8E+004 mg/L (at 25°C) Oral (L1436) ; Intramuscular (L1436). Both nicotinic acid and nicotinamide are efficiently absorbed from the stomach and small intestine. Niacin binds to Nicotinate D-ribonucleotide phyrophsopate phosphoribosyltransferase, Nicotinic acid phosphoribosyltransferase, Nicotinate N-methyltransferase and the Niacin receptor. Niacin is the precursor to nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are vital cofactors for dozens of enzymes. The mechanism by which niacin exerts its lipid lowering effects is not entirely understood, but may involve several actions, including a decrease in esterification of hepatic triglycerides. Niacin treatment also decreases the serum levels of apolipoprotein B-100 (apo B), the major protein component of the VLDL (very low-density lipoprotein) and LDL fractions. Niacin is rapidly metabolized and undergoes extensive first-pass metabolism in the liver. The drug is converted to several metabolites, including nicotinuric acid (NUA), nicotinamide, and nicotinamide adenine dinucleotide (NAD). At doses used to treat hyperlipoproteinemia, the principal metabolic pathways appear to be saturable, and niacin is thought to exhibit nonlinear, dose-dependent pharmacokinetics. (L1323) Half Life: 20-45 minutes. LD50: 7000 mg/kg (Oral, Rat) (T14) LD50: 730 mg/kg (Intraperitoneal, Rat) (T14) LD50: 3500 mg/kg (Subcutaneous, Mouse) (T14) No indication of carcinogenicity to humans (not listed by IARC). For the treatment of type IV and V hyperlipidemia. It is indicated as ajunctive therapy. It can be found in various foods, such as liver, chicken, beef, fish, cereal, peanuts and legumes. Niacin is also used as a pharmaceutical to reverse atherosclerosis. (A729) Niacin at extremely high doses can have life-threatening acute toxic reactions. Extremely high doses of niacin can also cause niacin maculopathy, a thickening of the macula and retina which leads to blurred vision and blindness. This maculopathy is reversible after stopping niacin intake. Side effects of hyperglycemia, cardiac arrhythmias and birth defects have also been reported. (A729) Nicotinic acid can cause vasodilation of cutaneous blood vessels resulting in increased blood flow, principally in the face, neck and chest. This produces the niacin- or nicotinic acid-flush. The niacin-flush is thought to be mediated via the prostaglandin prostacyclin. Histamine may also play a role in the niacin-flush. Flushing is the adverse reaction first observed after intake of a large dose of nicotinic acid, and the most bothersome one. Supportive measures should be undertaken in the event of an overdose. (L1712) 2009-07-21T20:27:16Z 2014-12-24T20:25:52Z Niacin C00253 100600 236800 15940 NIACINE Niacin DB00627 NIO 953 true OC(=O)C1=CN=CC=C1 C6H5NO2 InChI=1S/C6H5NO2/c8-6(9)5-2-1-3-7-4-5/h1-4H,(H,8,9) InChIKey=PVNIIMVLHYAWGP-UHFFFAOYSA-N 123.1094 123.032028409 Endogenous Solid 0.36 HMDB01488 CHEMBL573 913 <p>Joseph E. Toomey, Jr., &#8220;Electrochemical synthesis of niacin and other N-heterocyclic compounds.&#8221; U.S. Patent US5002641, issued 1914.</p>