Niacin

5 WARNINGS AND PRECAUTIONS Niacin extended-release tablet preparations should not be substituted for equivalent doses of immediate-release (crystalline) niacin. For patients switching from immediate-release niacin to niacin extended-release tablets, therapy with niacin extended-release tablets should be initiated with low doses (i.e., 500 mg at bedtime) and the niacin extended-release tablets dose should then be titrated to the desired therapeutic response [see Dosage and Administration (2.1) ] . Caution should also be used when niacin extended-release tablets are 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. Niacin extended-release tablets are contraindicated in patients with significant or unexplained hepatic impairment [see Contraindications (4) and Warnings and Precautions (5.3) ] 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 niacin extended-release tablets therapy. Severe hepatic toxicity has occurred in patients substituting sustained-release niacin for immediate-release niacin at equivalent doses. ( 5.3 ) Myopathy has been reported in patients taking niacin extended-release tablets. The risk for myopathy and rhabdomyolysis are increased among elderly patients; patients with diabetes, renal failure, or uncontrolled hypothyroidism; and patients being treated with a statin. ( 5.2 ) Liver enzyme abnormalities and monitoring: Persistent elevations in hepatic transaminase can occur. Monitor liver enzymes before and during treatment. ( 5.3 ) Use with caution in patients with unstable angina or in the acute phase of an MI. ( 5 ) Niacin extended-release tablets can increase serum glucose levels. Glucose levels should be closely monitored in diabetic or potentially diabetic patients particularly during the first few months of use or dose adjustment. ( 5.4 ) 5.1 Mortality and Coronary Heart Disease Morbidity Niacin extended-release tablets have not been shown to reduce cardiovascular morbidity or mortality among patients already treated with a statin. The Atherothrombosis Intervention in Metabolic Syndrome with Low HDL/High Triglycerides: Impact on Global Health Outcomes (AIM-HIGH) trial was a randomized placebo-controlled trial of 3414 patients with stable, previously diagnosed cardiovascular disease. Mean baseline lipid levels were LDL-C 74 mg/dL, HDL-C 35 mg/dL, non-HDL-C 111 mg/dL and median triglyceride level of 163 to 177 mg/dL. Ninety-four percent of patients were on background statin therapy prior to entering the trial. All participants received simvastatin, 40 to 80 mg per day, plus ezetimibe 10 mg per day if needed, to maintain an LDL-C level of 40 to 80 mg/dL, and were randomized to receive niacin extended-release tablets 1,500 to 2,000 mg/day (n=1718) or matching placebo (IR Niacin, 100 to 150 mg, n=1696). On-treatment lipid changes at two years for LDL-C were -12.0% for the simvastatin plus niacin extended-release tablets group and -5.5% for the simvastatin plus placebo group. HDL-C increased by 25.0% to 42 mg/dL in the simvastatin plus niacin extended-release tablets group and by 9.8% to 38 mg/dL in the simvastatin plus placebo group (P<0.001). Triglyceride levels decreased by 28.6% in the simvastatin plus niacin extended-release tablets group and by 8.1% in the simvastatin plus placebo group. The primary outcome was an ITT composite of the first study occurrence of coronary heart disease death, nonfatal myocardial infarction, ischemic stroke, hospitalization for acute coronary syndrome or symptom-driven coronary or cerebral revascularization procedures. The trial was stopped after a mean follow-up period of 3 years owing to a lack of efficacy. The primary outcome occurred in 282 patients in the simvastatin plus niacin extended-release tablets group (16.4%) and in 274 patients in the simvastatin plus placebo group (16.2%) (HR 1.02 [95% CI, 0.87 to 1.21], P=0.79. In an ITT analysis, there were 42 cases of first occurrence of ischemic stroke reported, 27 (1.6%) in the simvastatin plus niacin extended-release tablets group and 15 (0.9%) in the simvastatin plus placebo group, a non-statistically significant result (HR 1.79, [95%CI = 0.95 to 3.36], p=0.071). The on-treatment ischemic stroke events were 19 for the simvastatin plus niacin extended-release tablets group and 15 for the simvastatin plus placebo group [see Adverse Reactions (6.1) ] . 5.2 Skeletal Muscle Cases of rhabdomyolysis have been associated with concomitant administration of lipid-altering doses (≥1 g/day) of niacin and statins. Elderly patients and patients with diabetes, renal failure, or uncontrolled hypothyroidism are particularly at risk. 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. 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. 5.3 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. Niacin extended-release tablets 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 niacin extended-release tablets. Niacin preparations have been associated with abnormal liver tests. In three placebo-controlled clinical trials involving titration to final daily niacin extended-release tablets doses ranging from 500 to 3,000 mg, 245 patients received niacin extended-release tablets 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 niacin extended-release tablets. In these studies, fewer than 1% (2/245) of niacin extended-release tablets patients discontinued due to transaminase elevations greater than 2 times the ULN. Liver-related tests should be performed on all patients during therapy with niacin extended-release tablets. 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. 5.4 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 niacin extended-release tablets, 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: Niacin extended-release tablets have been associated with small but statistically significant dose-related reductions in platelet count (mean of -11% with 2,000 mg). Caution should be observed when Niacin extended-release tablets are administered concomitantly with anticoagulants; platelet counts should be monitored closely in such patients. Increase in Prothrombin Time (PT): Niacin extended-release tablets have 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 niacin extended-release tablets are 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, niacin extended-release tablets have been associated with small but statistically significant, dose-related reductions in phosphorus levels (mean of -13% with 2,000 mg). Although these reductions were transient, phosphorus levels should be monitored periodically in patients at risk for hypophosphatemia.