Niacin, also referred to as nicotinic acid is a B vitamin (vitamin B3). It is one of the essential human nutrients, meaning that it is required for normal body functioning but it can not be synthesized by the body at all. Niacin occurs naturally in animals and plant, such as chicken, beef, fish, eggs, leaf vegetables, tomatoes, carrots and sweet potatoes. Niacin is available under the brand names Niacin SR, Slo-Niacin, Niacor, Niaspan E, B-3-50 and B3-500-GR.

Niacin is usually prescribed for:
Prevention of the lack of natural niacin in the body
Treatment of pellagra (disorder caused by niacin deficiency and characterized by diarrhea, inflammation of the skin, mental problems and may lead to death if untreated)
Hypercholesterolemia (elevated blood levels of cholesterol)
Hypertriglyceridemia (elevated blood levels of triglycerides, a type of fat)
Niacin works by lowering the level of very-low-density lipoprotein (VLDL), or the bad cholesterol and increasing the level of high- density lipoprotein (HDL), or the good cholesterol. Elevated level of VLDL and decreased level of HDL may predispose to a heart attack, therefore Niacin is sometimes used for people who had or who are at high risk of a heart attack.

Niacin can be also used for treatment of coronary artery diseases, such as atherosclerosis (abnormal thickening, hardening and narrowing of arteries).

The recommended daily intake of Niacin is 16 mg for an adult man and 14 mg for an adult woman. The daily intake of Niacin should be increased during pregnancy and breastfeeding.

For treatment of pellagra in adult patients, Niacin is usually given in a dose of 100 to 250 mg orally, 3 times daily for 5 days.

Safety and effectiveness of Niacin in children and adolescents below 16 years are unknown.

Vomiting, diarrhea, itching, indigestion, headache, flushing, blurring of vision, dryness and increased pigmentation of the skin are the most commonly reported Niacin side effects.

Niacin was first extracted from animal livers by Conrad Elvehjen, a Norwegian biochemist and it was referred to as the “pellagra-preventing factor”.
Niacin is usually called vitamin B3, because it was the third of the B vitamins to be discovered.

Black Box Warnings: There are no available black box warnings for Niacin.

Common Niacin Side Effects:
Skin:
Increased pigmentation
Itching
Flushing
Dry skin

Gastrointestinal Tract (GIT):
Dyspepsia (disorders of digestion of foods)
Vomiting
Diarrhea
Abnormal liver function tests (LFTs)
Jaundice (yellowish discoloration of the skin, mucous membranes and whites of the eyes)
Peptic ulceration (hole in the inner lining of the stomach or first part of the small intestine)
Hepatitis, or inflammation of the liver has been reported during post-marketing experience

Eyes:
Toxic amblyopia (drop of vision due to niacin toxicity)
Macular edema (swelling in a part of the retina at the back of the eye called macula)
Blurring of vision has been reported during post-marketing experience

Metabolic and Endocrinal Systems:
Hyperuricemia (elevated blood uric acid level)
Gout (acute inflammation of joints due to elevated blood uric acid level. Symptoms include, redness, hotness, swelling and severe pain in the affected joint)
Hypophosphatemia (decreased blood phosphate level)
Impaired glucose tolerance (elevated blood glucose level)

Cardiovascular System (CVS):
Orthostatic hypotension (temporary drop of blood pressure due to suddenly standing up)
Tachycardia (rapid heart beats) and palpitations (abnormal awareness of heart beats) have been reported during post-marketing experience of Niacin

Other Common Niacin Side Effects:
Cough
Headache
Dizziness, insomnia, nervousness and paresthesia (pins and needles in the hands, legs and or feet) have been reported during post-marketing experience of Niacin

Serious Niacin Side Effects:
Gastrointestinal Tract (GIT):
Liver toxicity
Fulminant hepatic necrosis (death of liver cells with severe impairment of liver functions)

Other Serious Niacin Side Effects
Allergic reactions, such as anaphylaxis (severe and potentially fatal allergic reaction characterized by itching, skin rash, difficulty breathing, decreased blood pressure and swelling in the face, lips or tongue)
Arrhythmias (disorders of the normal rhythm of heart beats)
Thrombocytopenia (reduction in platelet count which may lead to spontaneous bleeding)
Syncope (sudden and transient loss of consciousness) has been reported during post-marketing experience of Niacin

Niacin Contraindications, Cautions, and Drug Interactions:
Niacin should not be used in people who are known to have hypersensitivity the drug.

Caution should be exercised when Niacin in used in people who have any of the following disorders:
Unexplained elevation of liver function tests (LFTs)
Active liver diseases
History of liver diseases
History of biliary tract diseases
Active peptic ulcer disease
History of peptic ulcer disease
Arterial bleeding
Alcohol abuse
Diabetes mellitus (DM)
Gout
Unstable angina (a type of angina, which is defined as severe chest pain due to insufficient blood supply to the heart)
Acute myocardial infarction (death of a part of heart muscle due to sudden occlusion of the blood supply to the heart)
Severe kidney diseases
Hypophosphatemia
Neurological diseases, such as myasthenia gravis

It is better not to take Niacin at the same time with any of the following medications:
Amlodipine
Atorvastatin
Fluvastatin
Lovastatin
Pitavastatin
Pravastatin
Simvastatin
Rosuvastatin
Red yeast.

The aforementioned contraindications, cautions and interactions of Niacin are the most important ones, for a complete list see the manufacturer’s prescriber guidelines, and for specific concerns consult your healthcare professional.

Pharmacology:
Niacin is metabolized through the liver. Its plasma half-life is 20 to 45 minutes.
Niacin is excreted mainly in the urine.

Pregnancy and Lactation:
According to the US Food and Drug Administration, Niacin is categorized as a category C medication, meaning that it may not be safe to take Niacin during pregnancy. Niacin should be discontinued before pregnancy because fetal side effects may occur.

Niacin is excreted into human breast milk. Safety of Niacin during breast feeding is unknown. Nursing mothers are advised to discontinue Niacin before breastfeeding because of potential serious side effects in infants.

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