Action/Kinetics: Niacin (nicotinic acid) and niacinamide are water-soluble, heat-resistant vitamins prepared synthetically. Niacin (after conversion to the active niacina-mide) is a component of the coen-zymes nicotinamide-adenine dinu-cleotide and nicotinamide-adenine dinucleotide phosphate, which are essential for oxidation-reduction reactions involved in lipid metabolism, glycogenolysis, and tissue respiration. Deficiency of niacin results in pellagra, the most common symptoms of which are dermatitis, diarrhea, and dementia. In high doses niacin also produces vasodilation. Reduces serum cholesterol and triglycerides in types II, III, IV, and V hy-perlipoproteinemia (mechanism unknown). Peak serum levels: 45 min; tV2: 45 min.
Uses: Prophylaxis and treatment of pellagra; niacin deficiency. Treat hy-perlipidemia in clients not responding to either diet or weight loss. Reduce the risk of recurrent nonfatal MI and promote regression of atherosclerosis when combined with bile-binding resins.
Contraindications: Severe hypotension, hemorrhage, arterial bleeding, liver dysfunction, peptic ulcer. Use of the extended-release tablets and capsules in children. Special Concerns: Extended-release niacin may be hepatotoxic. Use with caution in diabetics, gall bladder disease, and clients with gout.
Side Effects: GI: N&V, diarrhea, peptic ulcer activation, abdominal pain. Dermatologic: Flushing, warm feeling, skin rash, pruritus, dry skin, itching and tingling feeling, keratosis nigricans. Other: Hypotension, headache, macular cystoid edema, amblyopia. NOTE: Megadoses are accompanied by serious toxicity including the symptoms listed in the preceding as well as liver damage, hyperglycemia, hyperuricemia, arrhythmias, tachycardia, and dermatoses.
Drug Interactions: No drug interactions reported of concern to dentistry.
How Supplied: Niacin: Capsule: 100 mg; Capsule, extended release: 125 mg, 250 mg, 400 mg, 500 mg, 750 mg; Elixir: 50 mg/5 mL; Tablet: 50 mg, 100 mg, 250 mg, 500 mg; Tablet, extended release: 250 mg, 500 mg, 750 mg, 1,000 mg. Niacinamide: Tablet: 50 mg, 100 mg, 500 mg
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