What is the recommended dose of niacin (Vitamin B3) for therapy?

Recommended Dosing of Niacin (Vitamin B3) for Therapy

For lipid management, niacin therapy should be initiated at 500 mg daily at bedtime with a low-fat snack and gradually titrated to a maximum recommended dose of 2000 mg daily. 1

Initial Dosing and Titration

• Start with 500 mg extended-release niacin at bedtime with a low-fat snack 1
• Increase dose by no more than 500 mg every 4 weeks 1, 2
• Typical maintenance dose: 1000-2000 mg once daily 1
• Maximum recommended dose: 2000 mg daily (doses greater than 2000 mg are not recommended) 1, 2

Formulation Considerations

Different niacin formulations have distinct pharmacokinetic profiles that affect both efficacy and side effect profiles:

• Extended-release (ER) niacin: Preferred formulation with once-daily dosing, intermediate absorption rate, better balance of efficacy and tolerability 3
• Immediate-release (IR) niacin: Higher incidence of flushing but effective; typically dosed 100 mg three times daily initially, gradually increasing to target dose (up to 3 g/day divided into 2-3 doses) 3
• Sustained-release (SR) niacin: Higher risk of hepatotoxicity; not recommended as a substitute for ER niacin 1, 3

Monitoring During Therapy

1. Before initiating therapy:

   • Obtain baseline liver enzymes (ALT, AST)
   • Check fasting blood glucose or HbA1c
   • Measure uric acid levels 4, 5

2. During therapy:

   • Monitor liver enzymes every 3-6 months
   • Watch for persistent elevations in hepatic transaminases (>3 times upper limit of normal is concerning) 4, 1
   • Monitor glucose levels closely in diabetic patients 1

Managing Side Effects

Flushing is the most common side effect (affects >60% of patients) but typically decreases over time 6:

• Take with food or at bedtime with a low-fat snack 1
• Premedicate with aspirin 325 mg 30 minutes before niacin dose 6, 7
• Avoid alcohol, hot beverages, or spicy foods around time of niacin ingestion 1
• Women may respond to lower doses and experience more side effects 1, 2

Specific Clinical Indications

1. For primary hyperlipidemia and mixed dyslipidemia:

   • Target dose 1000-2000 mg daily 1

2. For triglyceride management:

   • If triglycerides 200-499 mg/dL: Consider niacin after LDL-lowering therapy 4
   • If triglycerides ≥500 mg/dL: Consider niacin before LDL-lowering therapy 4

3. For HDL-C <40 mg/dL:

   • Niacin can be used as a therapeutic option after LDL-C lowering therapy 4

Contraindications

Niacin is contraindicated in:

• Active liver disease or unexplained persistent elevations in hepatic transaminases
• Active peptic ulcer disease
• Arterial bleeding
• Hypersensitivity to niacin 1

Cautions and Pitfalls

• Never substitute equivalent doses of ER niacin for immediate-release niacin 1
• Use with caution in patients with unstable angina, acute MI, renal impairment, or diabetes 1
• Niacin plus statin combination therapy increases risk of myopathy/rhabdomyolysis 5, 1
• Recent evidence suggests niacin plus statin does not provide additional cardiovascular benefit beyond statin therapy alone 5, 1
• Niacin can increase serum glucose levels and may worsen glycemic control in diabetic patients 1

By following this dosing regimen and monitoring protocol, patients can achieve the lipid-modifying benefits of niacin therapy while minimizing adverse effects.