What is Niacin?
Niacin is a water soluble B-vitamin that has a dual action. Niacin or nicotinic acid has lipid-lowering action, but when niacin changes its chemical form, and becomes an amide (niacinamide or nicotinamide) then it functions as a vitamin only and has no action on the lipid levels.
It is the oldest cholesterol-lowering drug and large doses of niacin are required for it to have lipid-lowering benefits (around 5-6 times higher than the dose required for vitamin supplement action). Presently, less attention is being given to niacin as its main action is on HDL-C (good cholesterol) levels and not LDL-C (bad cholesterol) levels which are the target lipoproteins in all high risk patients.
Actions of Niacin
Niacin decreases the synthesis of triglycerides in the liver and bloodstream by inhibiting the enzymes involved in their formation.
It decreases the elimination of HDL-C from the body. Therefore niacin increases the levels of HDL-C by 30% to 40% and lowers triglycerides levels by 35% to 45% (as effectively as fibrates like fenofibrate and most potent statins like atorvastatin).
Niacin also decreases the levels of LDL-C by 20% to 30%, which is less than the effect shown by statins. It is the only lipid-lowering drug which decreases the levels of lipoprotein (a) markedly.
When is niacin prescribed?
Niacin is generally prescribed by doctors in combination with other lipid-lowering drugs. If you have altered levels of different parameters of a lipid profile like increased levels of LDL-C, triglycerides and low levels of HDL-C and high levels of Lp(a), then niacin is prescribed in combination with either statins or bile acid binding resins (like cholestyramine). If only HDL-C levels are decreased, then niacin alone may be recommended.
Dose and Schedule of Niacin Administration
To decrease the occurrence of side effects, it is important to strictly follow the instructions regarding the amount of dose, time and frequency of intake and when the dose can be increased or decreased.
Your physician may start niacin administration with a low dose which can be as low as 100 to 250 mg twice daily. Generally, the dose is increased at weekly intervals, going up to a maximum of 1.5 to 2 g/day in divided doses. In rare instances, an even higher dose may be recommended. The long acting preparations (commonly known as SR or ER) can be taken once a day.
Always consult with your doctor or pharmacist before you start any drug or change the dosage.
Side Effects of Niacin
The side effects seen with high doses of niacin are a limiting factor for its use. Common side effects include :
- dyspepsia (indigestion)
- dry skin
- liver damage
- hyperglycemia (increased levels of blood sugar)
The initial low dose and slow upward increase of the dosage decreases the incidence of flushing (sudden redness of face, neck and upper part of the body) and dyspepsia (upper abdominal pain, belching and nausea). Usually, both these effects disappear in couple of weeks as your body adjusts to the drug intake.
Always speak to your doctor before considering stopping a drug due to side effects.
- Pregnant and breast-feeding mothers should not take niacin.
- Always inform your doctor about your medical history as niacin is contraindicated in patients with gout (increased levels of uric acid) and is to be cautiously used by diabetics (‘sugar diabetes‘). Regular monitoring of blood sugar levels is advisable.
- The incidences of side-effects do increase with co-administration of drugs. The combined use of statins and niacin can increase the chance of development of myopathy (a disease of muscle) and liver and kidney damage. Refer to Statins Side Effects.
- Avoid drinking hot beverages and alcohol within a short period of taking niacin.
- Never take OTC preparations of niacin without first consulting with your doctor.
Niacin can prove to a highly beneficial drug, if used cautiously.