What is the recommended treatment for HIV (Human Immunodeficiency Virus) and TB (Tuberculosis) coinfection?

Treatment of HIV and TB Coinfection

For patients with HIV and TB coinfection, a rifabutin-based regimen consisting of isoniazid, rifabutin, pyrazinamide, and ethambutol for the initial 2 months, followed by isoniazid and rifabutin for 4 months is strongly recommended, with dosage adjustments based on antiretroviral therapy. 1

Initial Treatment Approach

Standard Treatment Regimen

• First-line regimen (6 months total):
  • Initial phase (2 months): Isoniazid, rifabutin, pyrazinamide, and ethambutol
  • Continuation phase (4 months): Isoniazid and rifabutin
  • All medications should be given daily or twice-weekly under directly observed therapy (DOT) 1

Antiretroviral Therapy (ART) Considerations

• If patient is already on ART with protease inhibitors or NNRTIs:
  • Use rifabutin instead of rifampin with appropriate dose adjustments:
    • Reduce to 150 mg daily when used with indinavir, nelfinavir, or amprenavir
    • Increase to 450 mg daily when used with efavirenz
    • Maintain 300 mg twice-weekly dosing regardless of antiretroviral medication 1
• If patient is not on ART at TB diagnosis:
  • Initiate TB treatment first
  • Delay ART by 4-8 weeks to:
    • Better identify source of side effects
    • Reduce severity of paradoxical reactions
    • Improve medication adherence 1

Special Populations

Pregnant Women

• Treat without delay using rifamycin-based regimens
• Include pyrazinamide despite previous concerns about teratogenicity
• Avoid aminoglycosides and capreomycin due to fetal risks 1

Children

• Use four-drug regimen including ethambutol at 15 mg/kg body weight
• Include ethambutol even in children too young for visual acuity testing 1

Drug-Resistant TB Management

Isoniazid-Resistant TB

• Treatment: Rifamycin, pyrazinamide, and ethambutol
• Duration: 6-9 months or 4 months after culture conversion 1

Rifampin-Resistant TB

• Initial phase: Isoniazid, streptomycin, pyrazinamide, and ethambutol
• Continuation phase: Isoniazid, streptomycin, and pyrazinamide
• Duration: 9 months total 1

Multidrug-Resistant TB (MDR-TB)

• Consult with MDR-TB specialists
• Typically includes an aminoglycoside and a fluoroquinolone
• Duration: 24 months after culture conversion
• Close monitoring with post-treatment follow-up every 4 months for 24 months 2

Monitoring and Side Effect Management

Required Monitoring

• Monthly clinical evaluation
• Regular assessment of medication side effects
• Follow-up of viral load and CD4 count 1

Common Side Effects and Management

• Paradoxical reactions: More common in HIV patients
  • Mild cases: Symptomatic treatment
  • Severe cases: Consider prednisone or methylprednisolone (1 mg/kg) 1
• Neurological side effects: Supplement with pyridoxine (vitamin B6) at 25-50 mg daily or 50-100 mg twice weekly for all patients receiving isoniazid 1

Important Considerations and Pitfalls

Critical Pitfalls to Avoid

1. Never use intermittent dosing in the intensive phase for HIV-TB coinfected patients due to increased risk of relapse with acquired rifamycin resistance 3
2. Never exclude rifamycins from the regimen due to concerns about drug interactions, as this delays sputum conversion and worsens outcomes 1
3. Never use three-drug regimens without rifamycins as they require extended treatment (18 months or 12 months after culture conversion) 1
4. Never delay TB treatment in pregnant women with HIV 1

Adherence Strategies

• Directly observed therapy (DOT) is essential for all HIV-TB coinfected patients 1
• Consider the timing of ART initiation based on CD4 count:
  • CD4 < 50 cells/mm³: Start ART within 2 weeks of TB treatment
  • CD4 > 50 cells/mm³: Start ART within 8-12 weeks of TB treatment 4

By following these guidelines, clinicians can effectively manage the complex challenges of HIV-TB coinfection while minimizing drug interactions, preventing resistance, and improving patient outcomes.