Niacin is a vitamin important in many chemical processes in the body; also known as vitamin B3.
Information about Niacin
Niacin, also known as nicotinic acid and vitamin B3, is a water soluble, essential B vitamin which, when given in high doses, is effective in lowering low density lipoprotein (LDL) cholesterol and raising high density lipoprotein (HDL) cholesterol, which makes this agent of unique value in the therapy of dyslipidemia.
Liver safety of Niacin
Niacin can cause mild-to-moderate serum aminotransferase elevations and high doses and certain formulations of niacin have been linked to clinically apparent, acute liver injury which can be severe as well as fatal.
Mechanism of action of Niacin
Niacin (nye" a sin) is a soluble B vitamin and pyridine derivative and an essential dietary element, deficiency of which causes pellagra.
RDA intake of Niacin
The recommended dietary allowance (RDA) of this vitamin is 14 to 16 mg daily in adults, and slightly more for pregnant women (18 mg) and less for children (2 to 12 mg). Niacin given at or around these doses is not associated with significant side effects or liver injury. Niacin is a component of most multivitamin and vitamin B preparations in concentrations close to the minimum daily requirement, which are not effective in lowering lipid levels. Niacin is also found in many herbal mixtures and energy drinks, but generally in low or modest doses.
Dosage and administration for Niacin
The doses of niacin used in the therapy of hyperlipidemia are far higher than the RDA and are generally in the range of 1 to 6 grams daily. When given at these doses, niacin has been shown to increase HDL and lower LDL cholesterol levels and to decrease rates of cardiovascular events in high risk individuals. The mechanism of action of niacin in hyperlipidemia is not well understood, but is believed to be related to inhibition of cAMP signaling pathways in adipocytes, which results in decreased release of lipids from fat cells.
FDA approval information for Niacin
Niacin was officially approved for use in the United States in 1957 and is still widely used, although its role in management of hyperlipidemia in patients taking statins and other cholesterol lowering agents remains uncertain and controversial. Regular niacin is available in multiple generic forms, under several brand names (including Niacor), in many concentrations as either tablets or capsules from 50 to 1,000 mg each. When used to treat hyperlipidemia, regular niacin is generally referred to as intermediate release [IR] niacin. IR-niacin must be taken several times daily and is associated with a high rate of cutaneous flushing. The recommended dosage for hyperlipidemia is 1 to 6 grams daily, starting at low doses (100 mg three times daily) and increasing at weekly intervals based upon tolerance and effect. Sustained release [SR] formulations of niacins have been developed which are available over-the-counter. SR niacin can be taken once daily and is less likely to cause flushing, but is not approved for use in hyperlipidemia and has been associated with a high rates of hepatotoxicity in some studies. Extended release (ER) capsules and tablets of niacin are available in concentrations ranging from 125 to 1,000 mg, which are approved for use in hyperlipidemia and have not been associated with a higher rate of hepatotoxicity compared to regular niacin.
Brand name for Niacin
Niacin ER is available by prescription and over-the-counter in generic forms and under several brand names such as Niaspan and Niobid. The recommended daily dosage of niacin ER ranges from 500 to 2,000 mg generally given once daily at bedtime. Niacin is also available in combination with other lipid lowering drugs such as lovastatin (Advicor).
Side effects of Niacin
Common side effects of niacin include nausea, fatigue, pruritus and flushing; flushing being a major dose-limiting side effect.
Lipid lowering medications
- Niacin (Nicotinic Acid)