Treatment Regimen for Tuberculosis

Initial Phase (First 2 Months)

The Centers for Disease Control and Prevention recommends a four-drug regimen consisting of isoniazid, rifampin, pyrazinamide, and ethambutol for the first 2 months of treatment 2
Ethambutol can be discontinued if drug susceptibility testing confirms that the TB strain is sensitive to both isoniazid and rifampin 2
The initial phase medications may be administered daily for the full 2 months (preferred approach) 3, 2
The initial phase medications may also be administered daily for 2 weeks followed by twice weekly administration for 6 weeks 4
The initial phase medications may also be administered three times weekly throughout the initial phase 3

The World Health Organization recommends a two-drug regimen of isoniazid and rifampin for 4 months 1, 2
The continuation phase medications may be administered daily (preferred approach) 3, 2
The continuation phase medications may be administered twice weekly under directly observed therapy (DOT) 3, 4
The continuation phase medications may be administered three times weekly under DOT 3

For patients with cavitary pulmonary TB who still have positive sputum cultures after 2 months of treatment, the continuation phase should be extended to 7 months (total treatment duration of 9 months) 1
HIV-positive TB patients should receive treatment for a minimum of 9 months and for at least 6 months beyond documented culture conversion 4
Higher rates of resistance to isoniazid and streptomycin may occur in certain populations 4
If drug resistance is detected, the treatment regimen should be appropriately revised 4, 1

The American Thoracic Society recommends DOT as the standard of practice to ensure adherence 2
When using DOT, medications may be given 5 days per week with appropriate dose adjustments 2
DOT should always be used when medications are administered less than 7 days per week 2

Patients should be medically assessed at least twice monthly for symptoms and by sputum smear until they become asymptomatic and smear negative 4
Cultures should be obtained at least monthly until negative 4
Patients should demonstrate sputum conversion within 3 months; if not, evaluation for noncompliance and drug resistance is necessary 4
Toxicity monitoring should be individualized based on the drugs used and patient factors related to toxicity (e.g., age, alcohol use) 4

Treatment failure is often due to patient noncompliance but may also result from ineffective regimens due to drug resistance 4
Adding a single drug to a failing regimen can lead to further drug resistance 1
For HIV-infected patients receiving antiretroviral therapy, TB treatment regimens might need to be adjusted 1
Patients with HIV and CD4+ counts <100 cells/mm³ should not receive highly intermittent (once or twice weekly) regimens due to risk of rifampin resistance 1
Patients treated with rifampin who are on methadone should have their methadone dosage increased to avoid withdrawal symptoms 4