niacin (nicotinic acid)
Brand: Niaspan, Slo-Niacin
Prototype Drug
Drug Class: antilipemic agent — niacin
Drug Family: antilipemic
Subclass: B-vitamin derivative lipid-lowering agent
Organ Systems: cardiovascular
Mechanism of Action
Activates GPR109A on adipocytes to inhibit hormone-sensitive lipase, reducing free fatty acid flux to the liver; decreases hepatic VLDL synthesis, raising HDL and lowering triglycerides and LDL. The flush reaction is mediated by prostaglandin D2 release from skin Langerhans cells.
GPR109A (niacin receptor)hepatic VLDL synthesisadipose hormone-sensitive lipase
Indications
- hypertriglyceridemia
- mixed dyslipidemia
- low HDL cholesterol
- adjunct in patients at high cardiovascular risk
Contraindications
- active liver disease
- active peptic ulcer disease
- arterial hemorrhage
- hypersensitivity to niacin
Adverse Effects
Common
- cutaneous flushing
- pruritus
- headache
- GI upset
- nausea
- diarrhea
- elevated uric acid
Serious
- hepatotoxicity (especially sustained-release forms)
- hyperglycemia
- gout exacerbation
- myopathy (with statins)
Pharmacokinetics (ADME)
| Absorption | rapidly and nearly completely absorbed orally; first-pass hepatic metabolism is saturable |
| Distribution | widely distributed; crosses into breast milk |
| Metabolism | hepatic conjugation and oxidation to nicotinamide and nicotinuric acid; extended-release formulations shift metabolism toward hepatic pathway, increasing hepatotoxicity risk |
| Excretion | renal; approximately 60-88% of dose excreted in urine |
| Half-life | approximately 45 minutes (immediate-release); approximately 6-7 hours (extended-release) |
| Onset | hours (lipid effects); weeks for full effect |
| Peak | 30-60 minutes (IR) |
| Duration | clinical benefit with regular dosing |
| Protein Binding | minimal |
| Vd | not well established |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| statins | additive myopathy risk, particularly at high niacin doses | moderate |
| bile acid sequestrants | may reduce niacin absorption if taken concurrently; separate by 4 or more hours | minor |
| antihypertensives | niacin-induced vasodilation may potentiate hypotension | moderate |
| aspirin | aspirin 325 mg taken 30 minutes before niacin blunts prostaglandin-mediated flush | minor |
Nursing Considerations
- Administer extended-release niacin at bedtime to minimize flush-related patient distress; advise patients to take aspirin 325 mg 30 minutes before the dose to attenuate flushing.
- Monitor fasting blood glucose and HbA1c; niacin impairs insulin sensitivity and can precipitate or worsen type 2 diabetes.
- Obtain baseline and periodic liver function tests; sustained-release formulations carry higher hepatotoxicity risk than immediate-release — do not substitute brands without medical review.
- Monitor uric acid and counsel patients with a history of gout; instruct patients to report joint pain, as niacin can precipitate gouty arthritis.
Clinical Pearls
- Despite raising HDL and lowering triglycerides, large RCTs (AIM-HIGH, HPS2-THRIVE) failed to show cardiovascular benefit when niacin was added to statin therapy, leading to a significant decline in clinical use.
- The extended-release formulation (Niaspan) is preferred over immediate-release for lipid management, but it carries paradoxically higher hepatotoxicity risk than the immediate-release form due to metabolic pathway saturation.
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Required
TDM Not required
Guideline Update pending
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.