What is the recommended dose of rifampin (Rifampin) for the treatment of latent tuberculosis infection?

Rifampin Dosing for Latent Tuberculosis Infection

For treatment of latent tuberculosis infection (LTBI), rifampin should be administered at a dose of 10 mg/kg daily (maximum 600 mg) for 4 months. 1

Dosing Guidelines

• Adults: 10 mg/kg once daily, not to exceed 600 mg daily 1
• Children: 10-20 mg/kg once daily, not to exceed 600 mg daily 1
• Administration: Should be taken on an empty stomach, either 1 hour before or 2 hours after meals, with a full glass of water 1

Treatment Regimens for LTBI

Preferred Regimens (in order of preference):

1. 4-month daily rifampin (4R)

   • Highly effective with better completion rates than isoniazid
   • Associated with fewer hepatotoxic events compared to isoniazid
   • Completion rates of 78% for rifampin vs 60% for isoniazid 2
   • Risk of grade 3-4 hepatitis: 0.7% with rifampin vs 3.8% with isoniazid 2

2. 9-month daily isoniazid (9H)

   • Traditional standard regimen
   • 300 mg daily for adults
   • Provides >90% protection when completed adequately 3
   • Higher rates of hepatotoxicity and lower completion rates

Special Considerations

Drug Interactions

• Rifampin induces hepatic microsomal enzymes, accelerating clearance of many medications 4:
  • Oral contraceptives
  • Anticoagulants
  • Corticosteroids
  • Oral hypoglycemic agents
  • Anticonvulsants
  • Methadone

HIV-Infected Patients

• Rifampin is generally contraindicated in patients taking HIV protease inhibitors 4
• For patients on antiretroviral therapy, consider:
  • Rifabutin (dose-adjusted) as an alternative to rifampin 4
  • Consult with HIV specialist for management of drug interactions

Monitoring

• Baseline liver function tests recommended for patients with:
  • HIV infection
  • Pregnancy or postpartum period
  • Chronic liver disease
  • Regular alcohol use 3
• Monthly clinical evaluations for adverse effects, particularly hepatotoxicity 3

Advantages of 4-Month Rifampin Regimen

• Non-inferior to 9-month isoniazid for preventing active TB 5
• Higher treatment completion rates (78% vs 60%) 2, 5
• Fewer serious adverse events, particularly hepatotoxicity 2, 6, 5
• More cost-effective than isoniazid regimen 6

Contraindications and Cautions

• Known hypersensitivity to rifamycins
• Concurrent use of certain antiretrovirals
• Patients should be advised that rifampin:
  • Colors body fluids orange (tears, sweat, urine)
  • May permanently discolor soft contact lenses 4
  • May reduce effectiveness of hormonal contraceptives 4

Important Warnings

• Always rule out active TB before starting LTBI treatment
• The 2-month rifampin plus pyrazinamide regimen is not recommended due to increased risk of severe hepatotoxicity 7
• For patients unable to tolerate rifampin, alternative regimens should be considered

The 4-month rifampin regimen offers significant advantages over the traditional 9-month isoniazid regimen in terms of safety, adherence, and cost-effectiveness while maintaining similar efficacy for preventing progression to active tuberculosis.