Nicotinic acid (Vitamin B3, Niacin) is a water-soluble vitamin and a lipid-modifying agent. At therapeutic doses (500mg and above), it acts as a potent antihyperlipidemic drug, significantly reducing serum levels of low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein (VLDL), triglycerides (TG), and lipoprotein(a) [Lp(a)], while increasing high-density lipoprotein cholesterol (HDL-C). It is also an essential nutrient for NAD/NADP coenzyme synthesis. In the Indian context, it is a cost-effective option for dyslipidemia management, especially for raising HDL-C, but its use is limited by a high incidence of flushing.
Adult: For dyslipidemia: Initiate at a low dose (100-250 mg once or twice daily) to improve tolerance. Titrate upward gradually over several weeks. The usual maintenance dose is 1-2 g/day, given in 2-3 divided doses with meals. The maximum recommended dose is 3 g/day. For Pellagra: 50-100 mg 3-4 times daily.
Note: Take with or immediately after a low-fat meal or snack (e.g., an apple, crackers) to reduce gastrointestinal upset and flushing. Avoid taking with hot drinks or alcohol, which can exacerbate flushing. Immediate-release tablets should be swallowed whole with a full glass of water. Do not crush or chew extended-release tablets.
Nicotinic acid's lipid-modifying effects are multifactorial and not fully understood. It acts primarily by inhibiting hepatic diacylglycerol acyltransferase 2 (DGAT2), a key enzyme in triglyceride synthesis, leading to reduced hepatic production of VLDL. The subsequent decrease in VLDL catabolism results in lower levels of its byproducts, IDL and LDL. It also enhances the catabolic rate of lipoprotein(a). The HDL-raising effect is mediated by decreasing the hepatic clearance of apolipoprotein A-I, a major component of HDL, via inhibition of the hepatocyte beta-chain ATP synthase receptor.
Pregnancy: Pregnancy Category C (US FDA). Animal studies have shown adverse effects. There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus. Not indicated for routine use in pregnancy.
Driving: May cause dizziness, especially during initial therapy or dose escalation. Patients should be cautioned about operating machinery or driving until they know how the medication affects them.
| HMG-CoA Reductase Inhibitors (Statins: Atorvastatin, Rosuvastatin) | Increased risk of myopathy and rhabdomyolysis. | Major |
| Aspirin (low-dose) | Aspirin (325mg given 30 min prior) can reduce the severity of nicotinic acid-induced flushing by inhibiting prostaglandin synthesis. | Moderate (Beneficial) |
| Antihypertensives (especially Vasodilators) | Additive vasodilation may potentiate hypotension and dizziness. | Moderate |
| Bile Acid Sequestrants (Colestyramine, Colestipol) | May bind nicotinic acid in the GI tract, reducing its absorption. Administer nicotinic acid at least 4-6 hours before or after the sequestrant. | Moderate |
| Antidiabetic Agents (Insulin, Sulfonylureas) | Nicotinic acid may increase blood glucose levels, necessitating dose adjustment of antidiabetic drugs. | Moderate |
| Alcohol | Potentiates cutaneous flushing and may increase risk of hepatotoxicity. | Major |
Same composition (Nicotinic acid (500mg)), different brands: