Also known as niacin, nicotinic acid is a water-soluble vitamin that decreases cholesterol, triglyceride, and apolipoprotein B-100 levels and increases the HDL level. The drug is available in immediate-release and extended-release tablets.
Nicotinic acid is rapidly and extensively absorbed following oral administration. It’s moderately bound to plasma proteins; its over-all binding ranges from 60% to 70%. The drug undergoes rapid me-tabolism by the liver to active and inactive metabolites. About 75% of the drug is excreted in urine.
The mechanism of action by which nicotinic acid lowers triglyc-eride and apolipoprotein levels is unknown. However, it may work by inhibiting hepatic synthesis of lipoproteins that contain apolipoprotein B-100, promoting lipoprotein lipase activity, reduc-ing free fatty acid mobilization from adipose tissue, and increasing fecal elimination of sterols.
Nicotinic acid is usually used in combination with other drugs to lower triglyceride levels in patients with type IV or V hyperlipi-demia who are at high risk for pancreatitis and to lower choles-terol and LDL levels in patients with hypercholesterolemia. It may also be used with other antilipemics to boost HDL levels.
Nicotinic acid is contraindicated in patients who are hypersen-sitive to nicotinic acid and in those with hepatic dysfunction, ac-tive peptic ulcer disease, or arterial bleeding.
Together, nicotinic acid and an HMG-CoA reductase inhibitor may increase the risk of myopathy or rhabdomyolysis.
§ Bile-sequestering drugs (cholestyramine, colesevelam, and colestipol) can bind with nicotinic acid and decrease its effective-ness.
§ When given with nicotinic acid, kava may increase the risk of hepatotoxicity. (See Adverse reactions to nicotinic acid.)