Prescription Drug Information: Niacin (Page 3 of 6)

6.2 Postmarketing Experience

Because the below reactions are reported voluntarily from a population of uncertain size, it is generally not possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

The following additional adverse reactions have been identified during post-approval use of niacin extended-release:

Hypersensitivity reactions, including anaphylaxis, angioedema, urticaria, flushing, dyspnea, tongue edema, larynx edema, face edema, peripheral edema, laryngismus, and vesiculobullous rash; maculopapular rash; dry skin; tachycardia; palpitations; atrial fibrillation; other cardiac arrhythmias; syncope; hypotension; postural hypotension; blurred vision; macular edema; peptic ulcers; eructation; flatulence; hepatitis; jaundice; decreased glucose tolerance; gout; myalgia; myopathy; dizziness; insomnia; asthenia; nervousness; paresthesia; dyspnea; sweating; burning sensation/skin burning sensation; skin discoloration, and migraine.

Clinical Laboratory Abnormalities

Chemistry: Elevations in serum transaminases [see Warnings and Precautions (5.3)] , LDH, fasting glucose, uric acid, total bilirubin, amylase and creatine kinase, and reduction in phosphorus.

Hematology: Slight reductions in platelet counts and prolongation in prothrombin time [see Warnings and Precautions (5.4)] .
To report SUSPECTED ADVERSE REACTIONS contact AvKARE, Inc. at 1-855-361-3993; email drugsafety@avkare.com; or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

7 DRUG INTERACTIONS

7.1 Statins

Caution should be used when prescribing niacin (≥1 gm/day) with statins as these drugs can increase risk of myopathy/rhabdomyolysis [see Warnings and Precautions (5) and Clinical Pharmacology (12.3)] .

7.2 Bile Acid Sequestrants

An in vitro study results suggest that the bile acid-binding resins have high niacin binding capacity. Therefore, 4 to 6 hours, or as great an interval as possible, should elapse between the ingestion of bile acid-binding resins and the administration of niacin extended-release [see Clinical Pharmacology (12.3)] .

7.3 Aspirin

Concomitant aspirin may decrease the metabolic clearance of nicotinic acid. The clinical relevance of this finding is unclear.

7.4 Antihypertensive Therapy

Niacin may potentiate the effects of ganglionic blocking agents and vasoactive drugs resulting in postural hypotension.

7.5 Other

Vitamins or other nutritional supplements containing large doses of niacin or related compounds such as nicotinamide may potentiate the adverse effects of niacin extended-release.

7.6 Laboratory Test Interactions

Niacin may produce false elevations in some fluorometric determinations of plasma or urinary catecholamines. Niacin may also give false-positive reactions with cupric sulfate solution (Benedict’s reagent) in urine glucose tests.

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Pregnancy Category C.

Animal reproduction studies have not been conducted with niacin or with niacin extended-release. It is also not known whether niacin at doses typically used for lipid disorders can cause fetal harm when administered to pregnant women or whether it can affect reproductive capacity. If a woman receiving niacin for primary hyperlipidemia becomes pregnant, the drug should be discontinued. If a woman being treated with niacin for hypertriglyceridemia conceives, the benefits and risks of continued therapy should be assessed on an individual basis.

8.3 Nursing Mothers

Niacin is excreted into human milk but the actual infant dose or infant dose as a percent of the maternal dose is not known. Because of the potential for serious adverse reactions in nursing infants from lipid-altering doses of nicotinic acid, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. No studies have been conducted with niacin extended-release in nursing mothers.

8.4 Pediatric Use

Safety and effectiveness of niacin therapy in pediatric patients (≤16 years) have not been established.

8.5 Geriatric Use

Of 979 patients in clinical studies of niacin extended-release, 21% of the patients were age 65 and over. No overall differences in safety and effectiveness were observed between these patients and younger patients, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

8.6 Renal Impairment

No studies have been performed in this population. Niacin extended-release should be used with caution in patients with renal impairment [see Warnings and Precautions (5)] .

8.7 Hepatic Impairment

No studies have been performed in this population. Niacin extended-release should be used with caution in patients with a past history of liver disease and/or who consume substantial quantities of alcohol. Active liver disease, unexplained transaminase elevations and significant or unexplained hepatic dysfunction are contraindications to the use of niacin extended-release [see Contraindications (4.0) and Warnings and Precautions (5.3)] .

8.8 Gender

Data from the clinical trials suggest that women have a greater hypolipidemic response than men at equivalent doses of niacin extended-release.

10 OVERDOSAGE

Supportive measures should be undertaken in the event of an overdose.

11 DESCRIPTION

Niacin extended-release tablets contains niacin, USP, which at therapeutic doses is an antihyperlipidemic agent. Niacin, USP (nicotinic acid, or 3-pyridinecarboxylic acid) is a white, crystalline powder, very soluble in water, with the following structural formula:

4097803e-figure-01

Niacin extended-release tablets are unscored, film-coated tablets for oral administration and are available in two tablet strengths containing 500 mg and 1000 mg niacin. The 500 mg is light orange to orange colored, round shaped, coated tablets debossed with ‘AN 321’ on one side and plain on the other side. The 1000 mg is light orange to orange colored, capsule shaped, coated tablets debossed with ‘AN 323’ on one side and plain on the other side. Niacin extended-release tablets also contain the following inactive ingredients: FD&C yellow #6/sunset yellow FCF aluminum lake, hydroxyethyl cellulose, hypromellose, iron oxide red, iron oxide yellow, polyethylene glycol 400, stearic acid and titanium dioxide.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

The mechanism by which niacin alters lipid profiles has not been well defined. It may involve several actions including partial inhibition of release of free fatty acids from adipose tissue, and increased lipoprotein lipase activity, which may increase the rate of chylomicron triglyceride removal from plasma. Niacin decreases the rate of hepatic synthesis of VLDL and LDL, and does not appear to affect fecal excretion of fats, sterols, or bile acids.

12.3 Pharmacokinetics

Absorption

Due to extensive and saturable first-pass metabolism, niacin concentrations in the general circulation are dose dependent and highly variable. Time to reach the maximum niacin plasma concentrations was about 5 hours following niacin extended-release. To reduce the risk of gastrointestinal (GI) upset, administration of niacin extended-release with a low-fat meal or snack is recommended.

Single-dose bioavailability studies have demonstrated that the 500 mg and 1000 mg tablet strengths are dosage form equivalent but the 500 mg and 750 mg tablet strengths are not dosage form equivalent.

Metabolism

The pharmacokinetic profile of niacin is complicated due to extensive first-pass metabolism that is dose-rate specific and, at the doses used to treat dyslipidemia, saturable. In humans, one pathway is through a simple conjugation step with glycine to form nicotinuric acid (NUA). NUA is then excreted in the urine, although there may be a small amount of reversible metabolism back to niacin. The other pathway results in the formation of nicotinamide adenine dinucleotide (NAD). It is unclear whether nicotinamide is formed as a precursor to, or following the synthesis of, NAD. Nicotinamide is further metabolized to at least N-methylnicotinamide (MNA) and nicotinamide-N-oxide (NNO). MNA is further metabolized to two other compounds, N-methyl-2-pyridone-5-carboxamide (2PY) and N-methyl-4-pyridone-5-carboxamide (4PY). The formation of 2PY appears to predominate over 4PY in humans. At the doses used to treat hyperlipidemia, these metabolic pathways are saturable, which explains the nonlinear relationship between niacin dose and plasma concentrations following multiple-dose niacin extended-release administration.

Nicotinamide does not have hypolipidemic activity; the activity of the other metabolites is unknown.

Elimination

Following single and multiple doses, approximately 60% to 76% of the niacin dose administered as niacin extended-release was recovered in urine as niacin and metabolites; up to 12% was recovered as unchanged niacin after multiple dosing. The ratio of metabolites recovered in the urine was dependent on the dose administered.

Pediatric Use

No pharmacokinetic studies have been performed in this population (≤16 years) [see Use in Specific Populations (8.4)] .

Geriatric Use

No pharmacokinetic studies have been performed in this population (> 65 years) [see Use in Specific Populations (8.5)] .

Renal Impairment

No pharmacokinetic studies have been performed in this population. Niacin extended-release should be used with caution in patients with renal disease [see Warnings and Precautions (5)] .

Hepatic Impairment

No pharmacokinetic studies have been performed in this population. Active liver disease, unexplained transaminase elevations and significant or unexplained hepatic dysfunction are contraindications to the use of niacin extended-release [see Contraindications (4) and Warnings and Precautions (5.3)] .

Gender

Steady-state plasma concentrations of niacin and metabolites after administration of niacin extended-release are generally higher in women than in men, with the magnitude of the difference varying with dose and metabolite. This gender differences observed in plasma levels of niacin and its metabolites may be due to gender-specific differences in metabolic rate or volume of distribution. Recovery of niacin and metabolites in urine, however, is generally similar for men and women, indicating that absorption is similar for both genders [see Gender (8.8)] .

Drug interactions

Fluvastatin

Niacin did not affect fluvastatin pharmacokinetics [see Drug Interactions (7.1)] .

Lovastatin

When niacin extended-release 2000 mg and lovastatin 40 mg were co-administered, niacin extended-release increased lovastatin C max and AUC by 2% and 14%, respectively, and decreased lovastatin acid C max and AUC by 22% and 2%, respectively. Lovastatin reduced niacin extended-release bioavailability by 2% to 3% [see Drug Interactions (7.1)] .

Simvastatin

When niacin extended-release 2000 mg and simvastatin 40 mg were co-administered, niacin extended-release increased simvastatin C max and AUC by 1% and 9%, respectively, and simvastatin acid C max and AUC by 2% and 18%, respectively. Simvastatin reduced niacin extended-release bioavailability by 2% [see Drug Interactions (7.1)] .

Bile Acid Sequestrants

An in vitro study was carried out investigating the niacin-binding capacity of colestipol and cholestyramine. About 98% of available niacin was bound to colestipol, with 10% to 30% binding to cholestyramine [see Drug Interactions (7.2)] .

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