Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
NICOLAR vs ATROMID-S
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Niacin (nicotinic acid) reduces hepatic production of VLDL and LDL by inhibiting diacylglycerol acyltransferase-2 (DGAT2) and decreasing free fatty acid mobilization from adipose tissue via activation of GPR109A (HM74A) receptor, leading to reduced triglyceride and LDL cholesterol synthesis. It also raises HDL cholesterol by decreasing hepatic clearance of apo A-I.
Inhibits hepatic triglyceride synthesis and increases lipoprotein lipase activity, leading to reduced VLDL and triglycerides.
Treatment of primary hyperlipidemia and mixed dyslipidemia (Fredrickson Types IIa and IIb),Reduction of risk of recurrent myocardial infarction in patients with prior MI and hyperlipidemia,Regression of coronary atherosclerosis (with bile acid sequestrant),Adjunct to diet in patients with elevated triglycerides (Types IV and V)
Type III hyperlipoproteinemia,Hypertriglyceridemia (Fredrickson types IV and V) not responsive to diet
NICOLAR (niacin extended-release) is typically initiated at 500 mg orally once daily at bedtime, after a low-fat snack. The dose is increased by 500 mg every 4 weeks as tolerated, up to a maximum of 2000 mg once daily.
500 mg to 1 g orally twice daily. Maximum dose 2 g/day.
Terminal elimination half-life is 14-24 hours in adults with normal renal function; clinically, this supports twice-daily dosing. In moderate renal impairment (Cr Cl 30-59 m L/min), half-life extends to 24-36 hours, requiring dose adjustment.
Terminal elimination half-life is 6-8 hours in patients with normal renal function; may be prolonged to 12-24 hours in renal impairment.
Extensively metabolized in the liver via two pathways: conjugation with glycine (major) to form nicotinuric acid, and N-methylation to N-methylnicotinamide. Also undergoes oxidation to nicotinamide N-oxide. CYP2E1 may be involved in some metabolic steps.
Hepatic via glucuronidation and oxidation; major metabolite is clofibric acid.
Primarily renal (60-70% as unchanged drug and metabolites), with 10-20% biliary/fecal. Hepatic metabolism to inactive metabolites accounts for ~30% of elimination.
Primarily renal excretion as glucuronide conjugates; approximately 60-70% of the dose is excreted in urine, 20-30% in feces via biliary elimination.
Approximately 90% bound to human serum albumin, primarily to albumin and to a lesser extent to alpha-1-acid glycoprotein.
>95% bound to plasma proteins, primarily albumin.
Volume of distribution is 1.5-2.5 L/kg, indicating extensive tissue distribution and high extravascular penetration, particularly into the respiratory tract.
0.11-0.14 L/kg; low Vd indicates limited extravascular distribution, consistent with high protein binding.
Oral: 30-60% due to first-pass metabolism. Inhaled: 10-20% reaching systemic circulation (majority acts locally with high lung deposition).
Oral: approximately 60-70% due to first-pass metabolism; administered as clofibrate (prodrug) which is hydrolyzed to active clofibric acid.
For patients with GFR <30 m L/min, reduce maximum dose to 1000 mg once daily due to increased risk of toxicity. For GFR 30-60 m L/min, no dose adjustment is required but monitor closely. No specific guidelines for dialysis.
GFR 30-59 m L/min: 500 mg twice daily. GFR 15-29 m L/min: 250 mg twice daily. GFR <15 m L/min: avoid use.
Contraindicated in patients with Child-Pugh class B or C cirrhosis. For Child-Pugh class A (mild impairment), initiate at 500 mg once daily and titrate cautiously, with maximum dose not exceeding 1000 mg once daily. Monitor liver function tests frequently.
Child-Pugh Class B or C: avoid use or reduce dose by at least 50%; not recommended in severe hepatic impairment.
Not approved for use in pediatric patients below 16 years of age for dyslipidemia. Safety and efficacy have not been established.
Not recommended; safety and efficacy not established in pediatric patients.
No specific dose adjustment is recommended solely based on age. However, elderly patients may have reduced renal function and increased risk of adverse effects (e.g., flushing, hyperglycemia). Initiate at the lowest starting dose (500 mg once daily) and titrate slowly. Monitor renal function and metabolic parameters closely.
Start at lower end of dosing range (500 mg twice daily). Monitor renal function; adjust dose based on GFR.
Severe hepatotoxicity, including fulminant hepatic necrosis, has occurred with sustained-release formulations. Do not substitute for equivalent doses of immediate-release niacin.
None
Hepatotoxicity: Monitor liver function tests; discontinue if persistent elevations or signs of hepatic injury.,Hyperuricemia and gout: May increase uric acid levels; use with caution in patients predisposed to gout.,Peptic ulcer: Niacin may reactivate or exacerbate peptic ulcer disease.,Facial flushing (prostaglandin-mediated): To reduce, take with aspirin 30 minutes prior, or use extended-release formulations.,Increased bleeding risk when used with anticoagulants.,Monitor glucose levels in diabetic patients; niacin may impair glucose tolerance.
Hepatotoxicity,Cholelithiasis,Renal impairment dose adjustment,Rhabdomyolysis risk with statins,Malignancy risk (hepatic, GI)
Active liver disease or unexplained persistent transaminase elevations,Active peptic ulcer disease,Arterial bleeding,Hypersensitivity to niacin or any component,Lactation (relative contraindication)
Hypersensitivity to clofibrate,Active liver disease,Severe renal dysfunction,Primary biliary cirrhosis,Pregnancy
Avoid high-fat meals with the dose, as they may increase the risk of flushing. Alcohol and hot beverages should be avoided close to dosing, as they can exacerbate flushing. Grapefruit juice has no significant interaction. Maintain a consistent diet to avoid fluctuations in blood glucose.
High-fat meals may reduce absorption; consistent timing of administration with food is recommended. Grapefruit juice may increase drug levels; avoid excessive intake. Alcohol may exacerbate hepatotoxicity.
NICOLAR (niacin) is classified as FDA Pregnancy Category C. Adverse effects have been observed in animal reproduction studies, but no adequate human studies exist. First trimester: potential risk based on animal data; use only if benefit outweighs risk. Second and third trimesters: no known specific risks but limited data; avoid high doses due to possible maternal hepatotoxicity and hyperglycemia.
FDA Pregnancy Category C. First trimester: Potential for teratogenicity based on animal studies showing skeletal and visceral anomalies. Human data limited; use only if benefit outweighs risk. Second and third trimesters: May cause fetal harm due to placental transfer and potential for reduced fetal growth.
Niacin is excreted into breast milk; M/P ratio not reported. Concentrations are low but caution is advised due to potential for high doses to cause adverse effects in the infant. Monitor infant for flushing, GI upset, or hepatotoxicity.
Excreted into breast milk in low amounts; M/P ratio not established. Due to potential for serious adverse effects in infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
No specific dose adjustments are recommended for pregnancy; however, due to increased plasma volume and clearance, therapeutic efficacy may require monitoring. Use the lowest effective dose and monitor clinical response. Avoid extended-release formulations due to higher hepatotoxicity risk.
No specific dosing adjustments recommended due to lack of data. However, pharmacokinetic changes in pregnancy (increased volume of distribution, altered metabolism) may necessitate careful monitoring and empiric dose adjustments based on clinical response and adverse effects.
NICOLAR is a brand name for niacin (nicotinic acid) extended-release. Doses should be taken at bedtime with a low-fat snack to reduce flushing. Avoid concomitant use with statins due to increased risk of myopathy. Monitor liver function tests and blood glucose regularly. Aspirin 325 mg taken 30 minutes prior can mitigate flushing.
ATROMID-S (clofibrate) is a fibric acid derivative primarily indicated for hyperlipidemia but its use is now limited due to increased non-cardiovascular mortality and cholelithiasis risk. Monitor liver function and prothrombin time (potentiates warfarin). Not first-line; consider statins or fibrates like fenofibrate.
Take this medication at bedtime with a low-fat snack to help reduce flushing and stomach upset.,Flushing, warmth, or tingling may occur, especially after starting or increasing the dose; taking aspirin 30 minutes before the dose can help.,Avoid alcohol and hot beverages near the time you take this medication as they can worsen flushing.,Report any unexplained muscle pain, tenderness, or weakness to your doctor, especially if accompanied by fever or malaise.,Regular blood tests to monitor liver function and blood sugar are necessary while on this medication.
Take with meals to reduce gastrointestinal upset.,Report unexplained muscle pain, tenderness, or weakness; may indicate myopathy.,Avoid alcohol as it may increase liver enzyme elevations.,Notify your doctor if you develop gallstones symptoms (e.g., right upper abdominal pain, nausea).,Use effective contraception as clofibrate may cause fetal harm.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about NICOLAR vs ATROMID-S, answered by our medical review team.
NICOLAR is a Antilipemic agent that works by Niacin (nicotinic acid) reduces hepatic production of VLDL and LDL by inhibiting diacylglycerol acyltransferase-2 (DGAT2) and decreasing free fatty acid mobilization from adipose tissue via activation of GPR109A (HM74A) receptor, leading to reduced triglyceride and LDL cholesterol synthesis. It also raises HDL cholesterol by decreasing hepatic clearance of apo A-I.. ATROMID-S is a Antilipemic Agent that works by Inhibits hepatic triglyceride synthesis and increases lipoprotein lipase activity, leading to reduced VLDL and triglycerides.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between NICOLAR and ATROMID-S depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of NICOLAR is: NICOLAR (niacin extended-release) is typically initiated at 500 mg orally once daily at bedtime, after a low-fat snack. The dose is increased by 500 mg every 4 weeks as tolerated, up to a maximum of 2000 mg once daily.. The standard adult dose of ATROMID-S is: 500 mg to 1 g orally twice daily. Maximum dose 2 g/day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between NICOLAR and ATROMID-S in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. NICOLAR is classified as Category C. NICOLAR (niacin) is classified as FDA Pregnancy Category C. Adverse effects have been observed in animal reproduction studies, but no adequate human studies exist. First trimester:. ATROMID-S is classified as Category C. FDA Pregnancy Category C. First trimester: Potential for teratogenicity based on animal studies showing skeletal and visceral anomalies. Human data limited; use only if benefit out. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.