What is the recommended dose of Anti-Tuberculosis Treatment (ATT) for a 42.5kg Indian boy diagnosed with pulmonary tuberculosis (TB)?

Recommended Dose of Anti-Tuberculosis Treatment for a 42.5kg Indian Boy with Pulmonary TB

For a 42.5kg Indian boy with pulmonary tuberculosis, the recommended treatment regimen should consist of isoniazid 10-15 mg/kg (425-637.5 mg, rounded to 400-600 mg), rifampin 10-20 mg/kg (425-850 mg, rounded to 450-600 mg), pyrazinamide 35 mg/kg (1487.5 mg, rounded to 1500 mg), and ethambutol 20 mg/kg (850 mg) daily for the first 2 months, followed by 4 months of isoniazid and rifampin. 1, 2, 3

Initial Intensive Phase (First 2 Months)

The standard four-drug regimen should include:

1. Isoniazid (H):

   • Dose: 10-15 mg/kg daily
   • For this patient: 425-637.5 mg, rounded to 400-600 mg daily
   • Maximum daily dose: 300 mg (therefore give 300 mg)
   • Pyridoxine (vitamin B6) 25-50 mg daily should be given to prevent peripheral neuropathy 1

2. Rifampin (R):

   • Dose: 10-20 mg/kg daily
   • For this patient: 425-850 mg, rounded to 450-600 mg daily
   • Maximum daily dose: 600 mg (therefore give 600 mg)

3. Pyrazinamide (Z):

   • Dose: 35 mg/kg (30-40 mg/kg range) daily
   • For this patient: 1487.5 mg, rounded to 1500 mg daily
   • Maximum daily dose: 2000 mg 2

4. Ethambutol (E):

   • Dose: 20 mg/kg (15-25 mg/kg range) daily
   • For this patient: 850 mg daily
   • Maximum daily dose: 2500 mg 1

Continuation Phase (Next 4 Months)

After the initial 2 months, continue with:

1. Isoniazid: 300 mg daily
2. Rifampin: 600 mg daily

Important Considerations

• Weight-based dosing: Since the patient weighs 42.5 kg, he is approaching the threshold where adult dosing begins (>40 kg or age >15 years) 1. Therefore, dosing should be carefully calculated based on his actual weight.

• Monitoring: Regular monitoring of liver function tests is essential, especially during the first two months of treatment 1, 4.

• Visual acuity: Since ethambutol is included in the regimen, baseline and periodic visual acuity testing should be performed 1.

• Treatment duration: The standard 6-month regimen (2HRZE/4HR) is recommended for pulmonary TB in children 1.

• Dosage adjustment: Dosages may need to be recalculated with weight gain during treatment 1.

• Directly Observed Therapy (DOT): Consider DOT to ensure adherence to the treatment regimen 1.

Alternative Dosing Options

If daily therapy is not feasible, thrice-weekly dosing under direct observation can be considered:

• Isoniazid: 15 mg/kg (637.5 mg, rounded to 600 mg)
• Rifampin: 10 mg/kg (425 mg, rounded to 450 mg)
• Pyrazinamide: See Table 10 in guidelines (approximately 50 mg/kg)
• Ethambutol: See Table 11 in guidelines (approximately 30 mg/kg)

However, daily dosing is preferred for optimal outcomes, especially during the intensive phase 1.

Cautions

• Hepatotoxicity: Monitor for signs of liver dysfunction, especially in the first 2 months of treatment 4
• Ocular toxicity: Regular vision testing is important for patients on ethambutol 1
• Drug interactions: Be aware of potential interactions with other medications 1

By following these dosing recommendations, the treatment has a high likelihood of success with close to 100% cure rate in patients with fully sensitive organisms 1.