NIACIN (VITAMIN B3, NICOTINIC ACID)
(nye'a-sin)
Niacor, Niaspan, Nicobid, Nico-400, Nicotinex, Novoniacin , Slo-Niacin, Tri-B3 
NIACINAMIDE (NICOTINAMIDE)
Classifications: vitamin b3 ; cardiovascular agent; antilipemic; lipid-lowering agent
Pregnancy Category: C

Availability

50 mg, 100 mg, 250 mg, 500 mg tablets; 125 mg, 250 mg, 400 mg, 500 mg, 750 mg, 1000 mg sustained release tablets, capsules

Actions

Water-soluble, heat-stable, B-complex vitamin (B3) that functions with riboflavin as a control agent in coenzyme system that converts protein, carbohydrate, and fat to energy through oxidation-reduction. Niacinamide, an amide of niacin, is used as an alternative in the prevention and treatment of pellagra.

Therapeutic Effects

Produces vasodilation by direct action on vascular smooth muscles. Inhibits hepatic synthesis of VLDL, cholesterol and triglyceride, and, indirectly, LDL. Large doses effectively reduce elevated serum cholesterol and total lipid levels in hypercholesterolemia and hyperlipidemic states.

Uses

In prophylaxis and treatment of pellagra, usually in combination with other B-complex vitamins, and in deficiency states accompanying carcinoid syndrome, isoniazid therapy, Hartnup's disease, and chronic alcoholism. Also in adjuvant treatment of hyperlipidemia (elevated cholesterol or triglycerides) in patients who do not respond adequately to diet or weight loss. Also as vasodilator in peripheral vascular disorders, Ménière's disease, and labyrinthine syndrome, as well as to counteract LSD toxicity and to distinguish between psychoses of dietary and nondietary origin.

Contraindications

Hypersensitivity to niacin; hepatic impairment; severe hypotension; hemorrhaging or arterial bleeding; active peptic ulcer; pregnancy (category C), lactation, and children <16 y.

Cautious Use

History of gallbladder disease, liver disease, and peptic ulcer; glaucoma; angina; coronary artery disease; diabetes mellitus; predisposition to gout; allergy.

Route & Dosage

Niacin Deficiency
Adult: PO 10–20 mg/d IV/IM/SC 25–100 mg 2–5 times/d

Pellagra
Adult: PO 300–500 mg/d in divided doses
Child: PO 50–100 mg t.i.d.

Hyperlipidemia
Adult: PO 1.5–3 g/d in divided doses, may increase up to 6 g/d if necessary
Child: PO 100–250 mg/d in 3 divided doses, may increase by 250 mg/d q2–3 wk as tolerated

Administration

Oral
Intravenous

PREPARE: Intermittent: Dilute 50–100 mg in 500 mL of NS to yield concentrations of 0.1–0.2 mg/mL.  

ADMINISTER: Intermittent: Give over 12–24 h.  

Adverse Effects (1%)

CNS: Transient headache, tingling of extremities, syncope. With chronic use: nervousness, panic, toxic amblyopia, proptosis, blurred vision, loss of central vision. CV: Generalized flushing with sensation of warmth, postural hypotension, vasovagal attacks, arrhythmias (rare). GI: Abnormalities of liver function tests; jaundice, bloating, flatulence, nausea, vomiting, GI disorders, activation of peptic ulcer, xerostomia. Skin: Increased sebaceous gland activity, dry skin, skin rash, pruritus, keratitis nigricans. Metabolic: Hyperuricemia, hyperglycemia, glycosuria, hypoprothrombinemia, hypoalbuminemia.

Diagnostic Test Interference

Niacin causes elevated serum bilirubin, uric acid, alkaline phosphatase, AST, ALT, LDH levels and may cause glucose intolerance. Decreases serum cholesterol 15–30% and may cause false elevations with certain fluorometric methods of determining urinary catecholamines. Niacin may cause false-positive urine glucose tests using copper sulfate reagents, e.g., Benedict's solution.

Interactions

Drug: Potentiates hypotensive effects of antihypertensive agents.

Pharmacokinetics

Absorption: Readily absorbed from GI tract. Peak: 20–70 min. Distribution: Distributed into breast milk. Metabolism: Metabolized in liver. Elimination: Excreted primarily in urine. Half-Life: 45 min.

Nursing Implications

Assessment & Drug Effects

Patient & Family Education


Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug