What is Niacin (Vitamin B3) used for?

Uses of Niacin (Vitamin B3)

Niacin is primarily used as a lipid-modifying agent to treat various forms of dyslipidemia, but its routine use has declined due to limited cardiovascular outcome benefits and significant side effects.

Primary Clinical Uses

Lipid Management

• Reduces LDL cholesterol by up to 25%
• Lowers triglycerides by up to 50%
• Increases HDL cholesterol by up to 30% (most effective agent available for raising HDL)
• Reduces lipoprotein(a) by up to 30% 1

Specific Indications

1. Primary hyperlipidemia and mixed dyslipidemia - as adjunct to diet when non-pharmacologic measures are inadequate 2
2. Secondary prevention - to reduce risk of recurrent myocardial infarction in patients with history of MI and hyperlipidemia 2
3. Atherosclerotic disease progression - in combination with bile acid binding resins to slow progression or promote regression of atherosclerotic disease 2
4. Severe hypertriglyceridemia - as adjunctive therapy for patients at risk of pancreatitis who don't respond adequately to dietary measures 2

Dosing Considerations

• Starting dose: 500 mg at bedtime to reduce side effects
• Maintenance dose: 1000-2000 mg daily (titrated gradually)
• Administration: Should be taken at bedtime after a low-fat snack 2
• Formulations:
  • Immediate-release (IR)
  • Sustained-release (SR)
  • Extended-release (ER) - preferred due to better side effect profile 3

Monitoring Requirements

According to ACC/AHA guidelines, the following should be monitored 4:

• Baseline hepatic transaminases, fasting blood glucose or HbA1c, and uric acid
• Repeat during dose titration and every 6 months thereafter

Safety Concerns and Limitations

Major Side Effects

• Flushing and pruritus - most common side effect, can be mitigated by taking aspirin 325 mg 30 minutes before dosing 4
• Hepatotoxicity - risk increases with sustained-release formulations 3
• Hyperglycemia - can worsen glycemic control in diabetic patients 4
• Hyperuricemia - can precipitate gout 4
• Gastrointestinal symptoms - abdominal pain, nausea 4

Contraindications

Niacin should not be used in patients with 4:

• Hepatic transaminase elevations >2-3 times upper limit of normal
• Persistent severe cutaneous symptoms
• Persistent hyperglycemia
• Acute gout
• Unexplained abdominal pain or GI symptoms
• New-onset atrial fibrillation or weight loss

Current Role in Therapy

The role of niacin has diminished in recent years due to:

1. Limited cardiovascular outcome benefits - The AIM-HIGH and HPS2-THRIVE trials showed no reduction in cardiovascular events when niacin was added to statin therapy 1

2. Significant side effect profile - Limiting patient adherence and clinical utility 1

3. Availability of better-tolerated alternatives - Statins have become first-line therapy for most dyslipidemias 4

Specialized Uses

Niacin may still be considered in specific scenarios:

• Statin intolerance - As an alternative when statins cannot be used 1
• Severe familial hypercholesterolemia - As part of combination therapy 1
• Very high Lp(a) levels - As one of few agents that can lower this parameter 1

Historical Context

Niacin has a long history in cardiovascular disease management. The Coronary Drug Project demonstrated that niacin monotherapy reduced recurrent myocardial infarction and long-term mortality in hypercholesterolemic men 1, 5. However, more recent evidence has led to a reevaluation of its role in contemporary practice.