Therapy with lipid-altering agents should be only one component of multiple risk factor intervention in individuals at significantly increased risk for atherosclerotic vascular disease due to hyperlipidemia. Niacin therapy is indicated as an adjunct to diet when the response to a diet restricted in saturated fat and cholesterol and other nonpharmacologic measures alone has been inadequate.
- Niaspan is indicated to reduce elevated TC, LDL-C, Apo B and TG levels, and to increase HDL-C in patients with primary hyperlipidemia and mixed dyslipidemia.
- Niaspan in combination with simvastatin or lovastatin is indicated for the treatment of primary hyperlipidemia and mixed dyslipidemia when treatment with Niaspan, simvastatin, or lovastatin monotherapy is considered inadequate.
- In patients with a history of myocardial infarction and hyperlipidemia, niacin is indicated to reduce the risk of recurrent nonfatal myocardial infarction.
- In patients with a history of coronary artery disease (CAD) and hyperlipidemia, niacin, in combination with a bile acid binding resin, is indicated to slow progression or promote regression of atherosclerotic disease.
- Niaspan in combination with a bile acid binding resin is indicated to reduce elevated TC and LDL-C levels in adult patients with primary hyperlipidemia.
- Niacin is also indicated as adjunctive therapy for treatment of adult patients with severe hypertriglyceridemia who present a risk of pancreatitis and who do not respond adequately to a determined dietary effort to control them.
Limitations of Use
No incremental benefit of Niaspan coadministered with simvastatin or lovastatin on cardiovascular morbidity and mortality over and above that demonstrated for niacin, simvastatin, or lovastatin monotherapy has been established.
Niaspan Dosage and Administration
Niaspan should be taken at bedtime, after a low-fat snack, and doses should be individualized according to patient response. Therapy with Niaspan must be initiated at 500 mg at bedtime in order to reduce the incidence and severity of side effects which may occur during early therapy. The recommended dose escalation is shown in Table 1 below.
Table 1. Recommended Dosing
| |
Week(s) |
Daily dose |
Niaspan Dosage |
INITIAL
TITRATION |
1 to 4 |
500 mg |
1 Niaspan 500 mg tablet at bedtime
|
| SCHEDULE |
5 to 8 |
1000 mg |
1 Niaspan 1000 mg tablet or
2 Niaspan 500 mg tablets at bedtime
|
| |
* |
1500 mg |
2 Niaspan 750 mg tablets or
3 Niaspan 500 mg tablets at bedtime
|
| |
* |
2000 mg |
2 Niaspan 1000 mg tablets or
4 Niaspan 500 mg tablets at bedtime |
| * After Week 8, titrate to patient response and tolerance. If response to 1000 mg daily is inadequate, increase dose to 1500 mg daily; may subsequently increase dose to 2000 mg daily. Daily dose should not be increased more than 500 mg in a 4-week period, and doses above 2000 mg daily are not recommended. Women may respond at lower doses than men. |
Maintenance Dose
The daily dosage of Niaspan should not be increased by more than 500 mg in any 4–week period. The recommended maintenance dose is 1000 mg (two 500 mg tablets or one 1000 mg tablet) to 2000 mg (two 1000 mg tablets or four 500 mg tablets) once daily at bedtime. Doses greater than 2000 mg daily are not recommended. Women may respond at lower Niaspan doses than men [see Clinical Studies (14.2)].
Single-dose bioavailability studies have demonstrated that two of the 500 mg and one of the 1000 mg tablet strengths are interchangeable but three of the 500 mg and two of the 750 mg tablet strengths are not interchangeable.
If lipid response to Niaspan alone is insufficient or if higher doses of Niaspan are not well tolerated, some patients may benefit from combination therapy with a bile acid binding resin or statin [see Drug Interactions (7.3), Concomitant Therapy below and Clinical Studies (14.3, 14.4)].
Flushing of the skin [see Adverse Reactions (6.1)] may be reduced in frequency or severity by pretreatment with aspirin (up to the recommended dose of 325 mg taken 30 minutes prior to Niaspan dose). Tolerance to this flushing develops rapidly over the course of several weeks. Flushing, pruritus, and gastrointestinal distress are also greatly reduced by slowly increasing the dose of niacin and avoiding administration on an empty stomach. Concomitant alcoholic, hot drinks or spicy foods may increase the side effects of flushing and pruritus and should be avoided around the time of Niaspan ingestion.
Equivalent doses of Niaspan should not be substituted for sustained-release (modified-release, timed-release) niacin preparations or immediate-release (crystalline) niacin [see Warnings and Precautions (5)]. Patients previously receiving other niacin products should be started with the recommended Niaspan titration schedule (see Table 1), and the dose should subsequently be individualized based on patient response.
If Niaspan therapy is discontinued for an extended period, reinstitution of therapy should include a titration phase (see Table 1).
Niaspan tablets should be taken whole and should not be broken, crushed or chewed before swallowing.
Concomitant Therapy
Concomitant Therapy with Lovastatin or Simvastatin
Patients already receiving a stable dose of lovastatin or simvastatin who require further TG-lowering or HDL-raising (e.g., to achieve NCEP non-HDL-C goals), may receive concomitant dosage titration with Niaspan per Niaspan recommended initial titration schedule [see Dosage and Administration (2)]. For patients already receiving a stable dose of Niaspan who require further LDL-lowering (e.g., to achieve NCEP LDL-C goals), the usual recommended starting dose of lovastatin and simvastatin is 20 mg once a day. Dose adjustments should be made at intervals of 4 weeks or more. Combination therapy with Niaspan and lovastatin or Niaspan and simvastatin should not exceed doses of 2000 mg Niaspan and 40 mg lovastatin or simvastatin daily.
Dosage in Patients with Renal or Hepatic Impairment
Use of Niaspan in patients with renal or hepatic impairment has not been studied. Niaspan is contraindicated in patients with significant or unexplained hepatic dysfunction. Niaspan should be used with caution in patients with renal impairment [see Warnings and Precautions (5)].
Dosage Forms and Strengths
- 500 mg unscored, medium-orange, film-coated, capsule-shaped tablets
- 750 mg unscored, medium-orange, film-coated, capsule-shaped tablets
- 1000 mg unscored, medium-orange, film-coated, capsule-shaped tablets
Contraindications
Niaspan is contraindicated in the following conditions:
- Active liver disease or unexplained persistent elevations in hepatic transaminases [see Warnings and Precautions (5.2)]
- Patients with active peptic ulcer disease
- Patients with arterial bleeding
- Hypersensitivity to niacin or any component of this medication [see Adverse Reactions (6.1)]
Warnings and Precautions
Niaspan preparations should not be substituted for equivalent doses of immediate-release (crystalline) niacin. For patients switching from immediate-release niacin to Niaspan, therapy with Niaspan should be initiated with low doses (i.e., 500 mg at bedtime) and the Niaspan dose should then be titrated to the desired therapeutic response [see Dosage and Administration (2)].
Caution should also be used when Niaspan is used in patients with unstable angina or in the acute phase of an MI, particularly when such patients are also receiving vasoactive drugs such as nitrates, calcium channel blockers, or adrenergic blocking agents.
Niacin is rapidly metabolized by the liver, and excreted through the kidneys. Niaspan is contraindicated in patients with significant or unexplained hepatic impairment [see Contraindications (4) and Warnings and Precautions (5.2)] and should be used with caution in patients with renal impairment. Patients with a past history of jaundice, hepatobiliary disease, or peptic ulcer should be observed closely during Niaspan therapy.
Skeletal Muscle
Cases of rhabdomyolysis have been associated with concomitant administration of lipid-altering doses (≥1 g/day) of niacin and statins. Physicians contemplating combined therapy with statins and Niaspan should carefully weigh the potential benefits and risks and should carefully monitor patients for any signs and symptoms of muscle pain, tenderness, or weakness, particularly during the initial months of therapy and during any periods of upward dosage titration of either drug. Periodic serum creatine phosphokinase (CPK) and potassium determinations should be considered in such situations, but there is no assurance that such monitoring will prevent the occurrence of severe myopathy.
The risk for myopathy and rhabdomyolysis are increased when lovastatin or simvastatin are coadministered with Niaspan, particularly in elderly patients and patients with diabetes, renal failure, or uncontrolled hypothyroidism.
Liver Dysfunction
Cases of severe hepatic toxicity, including fulminant hepatic necrosis, have occurred in patients who have substituted sustained-release (modified-release, timed-release) niacin products for immediate-release (crystalline) niacin at equivalent doses.
Niaspan should be used with caution in patients who consume substantial quantities of alcohol and/or have a past history of liver disease. Active liver diseases or unexplained transaminase elevations are contraindications to the use of Niaspan.
Niacin preparations have been associated with abnormal liver tests. In three placebo-controlled clinical trials involving titration to final daily Niaspan doses ranging from 500 to 3000 mg, 245 patients received Niaspan for a mean duration of 17 weeks. No patient with normal serum transaminase levels (AST, ALT) at baseline experienced elevations to more than 3 times the upper limit of normal (ULN) during treatment with Niaspan. In these studies, fewer than 1% (2/245) of Niaspan patients discontinued due to transaminase elevations greater than 2 times the ULN.
In three safety and efficacy studies with a combination tablet of Niaspan and lovastatin involving titration to final daily doses (expressed as mg of niacin/ mg of lovastatin) 500 mg/10 mg to 2500 mg/40 mg, ten of 1028 patients (1.0%) experienced reversible elevations in AST/ALT to more than 3 times the ULN. Three of ten elevations occurred at doses outside the recommended dosing limit of 2000 mg/40 mg; no patient receiving 1000 mg/20 mg had 3-fold elevations in AST/ALT.
Niacin extended-release and simvastatin can cause abnormal liver tests. In a simvastatin-controlled, 24 week study with a fixed dose combination of Niaspan and simvastatin in 641 patients, there were no persistent increases (more than 3x the ULN) in serum transaminases. In three placebo-controlled clinical studies of extended-release niacin there were no patients with normal serum transaminase levels at baseline who experienced elevations to more than 3x the ULN. Persistent increases (more than 3x the ULN) in serum transaminases have occurred in approximately 1% of patients who received simvastatin in clinical studies. When drug treatment was interrupted or discontinued in these patients, the transaminases levels usually fell slowly to pretreatment levels. The increases were not associated with jaundice or other clinical signs or symptoms. There was no evidence of hypersensitivity.
In the placebo-controlled clinical trials and the long-term extension study, elevations in transaminases did not appear to be related to treatment duration; elevations in AST levels did appear to be dose related. Transaminase elevations were reversible upon discontinuation of Niaspan.
Liver function tests should be performed on all patients during therapy with Niaspan. Serum transaminase levels, including AST and ALT (SGOT and SGPT), should be monitored before treatment begins, every 6 to 12 weeks for the first year, and periodically thereafter (e.g., at approximately 6-month intervals). Special attention should be paid to patients who develop elevated serum transaminase levels, and in these patients, measurements should be repeated promptly and then performed more frequently. If the transaminase levels show evidence of progression, particularly if they rise to 3 times ULN and are persistent, or if they are associated with symptoms of nausea, fever, and/or malaise, the drug should be discontinued.
Laboratory Abnormalities
Increase in Blood Glucose: Niacin treatment can increase fasting blood glucose. Frequent monitoring of blood glucose should be performed to ascertain that the drug is producing no adverse effects. Diabetic patients may experience a dose-related increase in glucose intolerance. Diabetic or potentially diabetic patients should be observed closely during treatment with Niaspan, particularly during the first few months of use or dose adjustment; adjustment of diet and/or hypoglycemic therapy may be necessary.
Reduction in platelet count: Niaspan has been associated with small but statistically significant dose-related reductions in platelet count (mean of -11% with 2000 mg). Caution should be observed when Niaspan is administered concomitantly with anticoagulants; platelet counts should be monitored closely in such patients.
Increase in Prothrombin Time (PT): Niaspan has been associated with small but statistically significant increases in prothrombin time (mean of approximately +4%); accordingly, patients undergoing surgery should be carefully evaluated. Caution should be observed when Niaspan is administered concomitantly with anticoagulants; prothrombin time should be monitored closely in such patients.
Increase in Uric Acid: Elevated uric acid levels have occurred with niacin therapy, therefore use with caution in patients predisposed to gout.
Decrease in Phosphorus: In placebo-controlled trials, Niaspan has been associated with small but statistically significant, dose-related reductions in phosphorus levels (mean of -13% with 2000 mg). Although these reductions were transient, phosphorus levels should be monitored periodically in patients at risk for hypophosphatemia.
Adverse Reactions
Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice.
Clinical Studies Experience
In the placebo-controlled clinical trials database of 402 patients (age range 21-75 years, 33% women, 89% Caucasians, 7% Blacks, 3% Hispanics, 1% Asians) with a median treatment duration of 16 weeks, 16% of patients on Niaspan and 4% of patients on placebo discontinued due to adverse reactions. The most common adverse reactions in the group of patients treated with Niaspan that led to treatment discontinuation and occurred at a rate greater than placebo were flushing (6% vs. 0%), rash (2% vs. 0%), diarrhea (2% vs. 0%), nausea (1% vs. 0%), and vomiting (1% vs. 0%). The most commonly reported adverse reactions (incidence >5% and greater than placebo) in the Niaspan controlled clinical trial database of 402 patients were flushing, diarrhea, nausea, vomiting, increased cough and pruritus.
In the placebo-controlled clinical trials, flushing episodes (i.e., warmth, redness, itching and/or tingling) were the most common treatment-emergent adverse reactions (reported by as many as 88% of patients) for Niaspan. Spontaneous reports suggest that flushing may also be accompanied by symptoms of dizziness, tachycardia, palpitations, shortness of breath, sweating, burning sensation/skin burning sensation, chills, and/or edema, which in rare cases may lead to syncope. In pivotal studies, 6% (14/245) of Niaspan patients discontinued due to flushing. In comparisons of immediate-release (IR) niacin and Niaspan, although the proportion of patients who flushed was similar, fewer flushing episodes were reported by patients who received Niaspan. Following 4 weeks of maintenance therapy at daily doses of 1500 mg, the incidence of flushing over the 4-week period averaged 8.6 events per patient for IR niacin versus 1.9 following Niaspan.
Other adverse reactions occurring in ≥5% of patients treated with Niaspan and at an incidence greater than placebo are shown in Table 2 below.
Table 2. Treatment-Emergent Adverse Reactions by Dose Level in ≥ 5% of Patients and at an Incidence Greater than Placebo; Regardless of Causality Assessment in Placebo-Controlled Clinical Trials
| |
Placebo-Controlled Studies
Niaspan Treatment@ |
| |
|
Recommended Daily
Maintenance Doses † |
| |
Placebo |
500 mg‡ |
1000 mg |
1500 mg |
2000 mg |
| |
(n = 157) |
(n = 87) |
(n = 110) |
(n = 136) |
(n = 95) |
| |
% |
% |
% |
% |
% |
| Gastrointestinal Disorders |
|
|
|
|
|
| Diarrhea |
13 |
7 |
10 |
10 |
14 |
| Nausea |
7 |
5 |
6 |
4 |
11 |
| Vomiting |
4 |
0 |
2 |
4 |
9 |
| Respiratory |
|
|
|
|
|
| Cough, Increased |
6 |
3 |
2 |
< 2 |
8 |
| Skin and Subcutaneous Tissue Disorders |
|
|
|
|
|
| Pruritus |
2 |
8 |
0 |
3 |
0 |
| Rash |
0 |
5 |
5 |
5 |
0 |
| Vascular Disorders |
|
|
|
|
|
| Flushing& |
19 |
68 |
69 |
63 |
55 |
Note: Percentages are calculated from the total number of patients in each column.
† Adverse reactions are reported at the initial dose where they occur.
@ Pooled results from placebo-controlled studies; for Niaspan, n = 245 and median treatment duration = 16 weeks. Number of Niaspan patients (n) are not additive across doses.
‡ The 500 mg/day dose is outside the recommended daily maintenance dosing range [see Dosage and Administration (2)].
& 10 patients discontinued before receiving 500 mg, therefore they were not included. |
In general, the incidence of adverse events was higher in women compared to men.
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 Niaspan:
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 (5.2)], 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 (5.3)].
Drug Interactions
Statins
Caution should be used when prescribing niacin (≥1 gm/day) with statins as these drugs can increase risk of myopathy/rhabdomyolysis. Combination therapy with Niaspan and lovastatin or Niaspan and simvastatin should not exceed doses of 2000 mg Niaspan and 40 mg lovastatin or simvastatin daily. [see Warnings and Precautions (5) and Clinical Pharmacology (12.3)].
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 Niaspan [see Clinical Pharmacology (12.3)].
Aspirin
Concomitant aspirin may decrease the metabolic clearance of nicotinic acid. The clinical relevance of this finding is unclear.
Antihypertensive Therapy
Niacin may potentiate the effects of ganglionic blocking agents and vasoactive drugs resulting in postural hypotension.
Other
Vitamins or other nutritional supplements containing large doses of niacin or related compounds such as nicotinamide may potentiate the adverse effects of Niaspan.
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.
USE IN SPECIFIC POPULATIONS
Pregnancy
Pregnancy Category C.
Animal reproduction studies have not been conducted with niacin or with Niaspan. 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.
All statins are contraindicated in pregnant and nursing women. When Niaspan is administered with a statin in a woman of childbearing potential, refer to the pregnancy category and product labeling for the statin.
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 Niaspan in nursing mothers.
Pediatric Use
Safety and effectiveness of niacin therapy in pediatric patients (≤16 years) have not been established.
Geriatric Use
Of 979 patients in clinical studies of Niaspan, 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.
Renal Impairment
No studies have been performed in this population. Niaspan should be used with caution in patients with renal impairment [see Warnings and Precautions (5)].
Hepatic Impairment
No studies have been performed in this population. Niaspan 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 Niaspan [see Contraindications (4.0) and Warnings and Precautions (5.2)].
Gender
Data from the clinical trials suggest that women have a greater hypolipidemic response than men at equivalent doses of Niaspan.
Overdosage
Supportive measures should be undertaken in the event of an overdose.
Niaspan Description
Niaspan (niacin tablet, film-coated extended-release), contains niacin, which at therapeutic doses is an antihyperlipidemic agent. Niacin (nicotinic acid, or 3-pyridinecarboxylic acid) is a white, crystalline powder, very soluble in water, with the following structural formula:
Niaspan is an unscored, medium-orange, film-coated tablet for oral administration and is available in three tablet strengths containing 500, 750, and 1000 mg niacin. Niaspan tablets also contain the inactive ingredients hypromellose, povidone, stearic acid, and polyethylene glycol, and the following coloring agents: FD&C yellow #6/sunset yellow FCF Aluminum Lake, synthetic red and yellow iron oxides, and titanium dioxide.
Niaspan - Clinical Pharmacology
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.
Pharmacodynamics
Niacin functions in the body after conversion to nicotinamide adenine dinucleotide (NAD) in the NAD coenzyme system. Niacin (but not nicotinamide) in gram doses reduces total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and triglycerides (TG), and increases high-density lipoprotein cholesterol (HDL-C). The magnitude of individual lipid and lipoprotein responses may be influenced by the severity and type of underlying lipid abnormality. The increase in HDL-C is associated with an increase in apolipoprotein A-I (Apo A-I) and a shift in the distribution of HDL subfractions. These shifts include an increase in the HDL2:HDL3 ratio, and an elevation in lipoprotein A-I (Lp A-I, an HDL-C particle containing only Apo A-I). Niacin treatment also decreases serum levels of apolipoprotein B-100 (Apo B), the major protein component of the very low-density lipoprotein (VLDL) and LDL fractions, and of Lp(a), a variant form of LDL independently associated with coronary risk. In addition, preliminary reports suggest that niacin causes favorable LDL particle size transformations, although the clinical relevance of this effect requires further investigation. The effect of niacin-induced changes in lipids/proteins on cardiovascular morbidity or mortality in individuals without preexisting coronary disease has not been established.
A variety of clinical studies have demonstrated that elevated levels of TC, LDL-C, and Apo B promote human atherosclerosis. Similarly, decreased levels of HDL-C are associated with the development of atherosclerosis. Epidemiological investigations have established that cardiovascular morbidity and mortality vary directly with the level of Total-C and LDL-C, and inversely with the level of HDL-C.
Like LDL, cholesterol-enriched triglyceride-rich lipoproteins, including VLDL, intermediate-density lipoprotein (IDL), and their remnants, can also promote atherosclerosis. Elevated plasma TG are frequently found in a triad with low HDL-C levels and small LDL particles, as well as in association with non-lipid metabolic risk factors for coronary heart disease (CHD). As such, total plasma TG has not consistently been shown to be an independent risk factor for CHD. Furthermore, the independent effect of raising HDL-C or lowering TG on the risk of coronary and cardiovascular morbidity and mortality has not been determined.
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 Niaspan. To reduce the risk of gastrointestinal (GI) upset, administration of Niaspan 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 Niaspan 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 Niaspan 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. Niaspan 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 Niaspan [see Contraindications (4) and Warnings and Precautions (5.2)].
Gender
Steady-state plasma concentrations of niacin and metabolites after administration of Niaspan 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 Niaspan 2000 mg and lovastatin 40 mg were co-administered, Niaspan increased lovastatin Cmax and AUC by 2% and 14%, respectively, and decreased lovastatin acid Cmax and AUC by 22% and 2%, respectively. Lovastatin reduced Niaspan bioavailability by 2-3% [see Drug Interactions (7.1)].
Simvastatin
When Niaspan 2000 mg and simvastatin 40 mg were co-administered, Niaspan increased simvastatin Cmax and AUC by 1% and 9%, respectively, and simvastatin acid Cmax and AUC by 2% and 18%, respectively. Simvastatin reduced Niaspan 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)].
Nonclinical Toxicology
Carcinogenesis and Mutagenesis and Impairment of Fertility
Niacin administered to mice for a lifetime as a 1% solution in drinking water was not carcinogenic. The mice in this study received approximately 6 to 8 times a human dose of 3000 mg/day as determined on a mg/m2 basis. Niacin was negative for mutagenicity in the Ames test. No studies on impairment of fertility have been performed. No studies have been conducted with Niaspan regarding carcinogenesis, mutagenesis, or impairment of fertility.
Clinical Studies
Niacin Clinical Studies
The role of LDL-C in atherogenesis is supported by pathological observations, clinical studies, and many animal experiments. Observational epidemiological studies have clearly established that high TC or LDL-C and low HDL-C are risk factors for CHD. Additionally, elevated levels of Lp(a) have been shown to be independently associated with CHD risk.
Niacin’s ability to reduce mortality and the risk of definite, nonfatal myocardial infarction (MI) has been assessed in long-term studies. The Coronary Drug Project, completed in 1975, was designed to assess the safety and efficacy of niacin and other lipid-altering drugs in men 30 to 64 years old with a history of MI. Over an observation period of 5 years, niacin treatment was associated with a statistically significant reduction in nonfatal, recurrent MI. The incidence of definite, nonfatal MI was 8.9% for the 1,119 patients randomized to nicotinic acid versus 12.2% for the 2,789 patients who received placebo (p<0.004). Total mortality was similar in the two groups at 5 years (24.4% with nicotinic acid versus 25.4% with placebo; p=N.S.). At the time of a 15-year follow-up, there were 11% (69) fewer deaths in the niacin group compared to the placebo cohort (52.0% versus 58.2%; p=0.0004). However, mortality at 15 years was not an original endpoint of the Coronary Drug Project. In addition, patients had not received niacin for approximately 9 years, and confounding variables such as concomitant medication use and medical or surgical treatments were not controlled.
The Cholesterol-Lowering Atherosclerosis Study (CLAS) was a randomized, placebo-controlled, angiographic trial testing combined colestipol and niacin therapy in 162 non-smoking males with previous coronary bypass surgery. The primary, per-subject cardiac endpoint was global coronary artery change score. After 2 years, 61% of patients in the placebo cohort showed disease progression by global change score (n=82), compared with only 38.8% of drug-treated subjects (n=80), when both native arteries and grafts were considered (p<0.005); disease regression also occurred more frequently in the drug-treated group (16.2% versus 2.4%; p=0.002). In a follow-up to this trial in a subgroup of 103 patients treated for 4 years, again, significantly fewer patients in the drug-treated group demonstrated progression than in the placebo cohort (48% versus 85%, respectively; p<0.0001).
The Familial Atherosclerosis Treatment Study (FATS) in 146 men ages 62 and younger with Apo B levels ≥125 mg/dL, established coronary artery disease, and family histories of vascular disease, assessed change in severity of disease in the proximal coronary arteries by quantitative arteriography. Patients were given dietary counseling and randomized to treatment with either conventional therapy with double placebo (or placebo plus colestipol if the LDL-C was elevated); lovastatin plus colestipol; or niacin plus colestipol. In the conventional therapy group, 46% of patients had disease progression (and no regression) in at least one of nine proximal coronary segments; regression was the only change in 11%. In contrast, progression (as the only change) was seen in only 25% in the niacin plus colestipol group, while regression was observed in 39%. Though not an original endpoint of the trial, clinical events (death, MI, or revascularization for worsening angina) occurred in 10 of 52 patients who received conventional therapy, compared with 2 of 48 who received niacin plus colestipol.
The Harvard Atherosclerosis Reversibility Project (HARP) was a randomized placebo-controlled, 2.5-year study of the effect of a stepped-care antihyperlipidemic drug regimen on 91 patients (80 men and 11 women) with CHD and average baseline TC levels less than 250 mg/dL and ratios of TC to HDL-C greater than 4.0. Drug treatment consisted of an HMG-CoA reductase inhibitor administered alone as initial therapy followed by addition of varying dosages of either a slow-release nicotinic acid, cholestyramine, or gemfibrozil. Addition of nicotinic acid to the HMG-CoA reductase inhibitor resulted in further statistically significant mean reductions in TC, LDL-C, and TG, as well as a further increase in HDL-C in a majority of patients (40 of 44 patients). The ratios of TC to HDL-C and LDL-C to HDL-C were also significantly reduced by this combination drug regimen [see Warnings and Precautions (5.1)].
Niaspan Clinical Studies
Placebo-Controlled Clinical Studies in Patients with Primary Hyperlipidemia and Mixed Dyslipidemia: In two randomized, double-blind, parallel, multi-center, placebo-controlled trials, Niaspan dosed at 1000, 1500 or 2000 mg daily at bedtime with a low-fat snack for 16 weeks (including 4 weeks of dose escalation) favorably altered lipid profiles compared to placebo (Table 3). Women appeared to have a greater response than men at each Niaspan dose level (see Gender Effect, below).
Table 3. Lipid Response to Niaspan Therapy
