What is the weight-based dosage of Anti-Tuberculosis (ATT) therapy for a 53kg female?

From the Guidelines

For a 53kg female, the weight-based dosage for Anti-Tuberculosis Treatment (ATT) therapy would include Isoniazid 5mg/kg/day (265mg, rounded to 300mg daily), Rifampin 10mg/kg/day (530mg, rounded to 600mg daily), Ethambutol 15-20mg/kg/day (800-1060mg, typically 800mg daily), and Pyrazinamide 20-25mg/kg/day (1060-1325mg, typically 1000-1500mg daily) as per the guidelines outlined in the American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America treatment of tuberculosis guidelines 1.

Key Considerations for ATT Therapy

• The standard regimen consists of a 2-month intensive phase with all four drugs (HRZE), followed by a 4-month continuation phase with just Isoniazid and Rifampin (HR) 1.
• Pyridoxine (vitamin B6) 25-50mg daily should be added to prevent peripheral neuropathy from Isoniazid.
• These medications should be taken as a single daily dose, preferably on an empty stomach.
• Regular monitoring for adverse effects is essential, including monthly liver function tests for the first three months and baseline visual acuity and color discrimination tests when using Ethambutol.

Dosage Adjustments and Supervision

• Dosage adjustments may be necessary for renal impairment.
• Treatment should be supervised by a healthcare provider experienced in TB management to ensure adherence and monitor for drug interactions or side effects.

Important Notes

• The doses per weight are based on ideal body weight, and children weighing more than 40 kg should be dosed as adults 1.
• The drug doses may need to be adjusted when there is concomitant use of protease inhibitors or nonnucleoside reverse transcriptase inhibitors, and Ethambutol should be used with caution in children less than 5 years of age, in whom visual acuity cannot be monitored 1.

From the FDA Drug Label

DOSAGE and ADMINISTRATION ETHAMBUTOL HCl should not be used alone, in initial treatment or in tretreatment. Initial Treatment: In patients who have not received previous antituberculous therapy, administer ETHAMBUTOL HCl 15 mg/kg (7 mg/lb) of body weight, as a single oral dose once every 24 hours Retreatment: In patients who have received previous antituberculous therapy, administer ETHAMBUTOL HCl 25 mg/kg (11 mg/lb) of body weight, as a single oral dose once every 24 hours

For a 53kg female, the weight-wise dosage of ethambutol for initial treatment is 15 mg/kg.

• The dose would be: 53 kg * 15 mg/kg = 795 mg
• According to the weight-dose table, the closest dose is 900 mg for a weight range of 557 – 64 kg for the 15 mg/kg schedule, but since the patient's weight is 53kg, we should look at the table for the correct dose range.
• For a weight of 53kg, the correct dose range is 50-57 kg, which corresponds to a dose of 700 mg for the 15 mg/kg schedule, but since 53kg is closer to 50-54 kg for the 15mg/kg schedule in the table which is 700 mg for 50-57 kg and 800 mg is not the correct dose for this weight, 700 mg is not the exact dose for 53 kg, we should calculate it, 53 kg * 15 mg/kg = 795 mg which is closer to 700-800 mg but 795 mg is closer to 800 mg than 700 mg but still we should use 700-800 mg range to choose the dose, in this case 800 mg is not available for 53 kg in the table but 700 mg and 800 mg are available for the weight range, we should use 800 mg for 53 kg as it is closer.
• For retreatment, the dose would be: 53 kg * 25 mg/kg = 1325 mg
• According to the weight-dose table, the closest dose is 1300 mg for a weight range of 584 – 90 kg for the 25 mg/kg schedule, but since the patient's weight is 53kg, we should look at the table for the correct dose range.
• For a weight of 53kg, the correct dose range is 545.5 – 50 kg and 50-54 kg for the 25mg/kg schedule in the table which is 1200 mg for 545.5-50 kg and 1300 mg for 50-54 kg, 1200 mg is not the exact dose for 53 kg, we should calculate it, 53 kg * 25 mg/kg = 1325 mg which is closer to 1300 mg than 1200 mg.
• The dose for isoniazid is 5 mg/kg up to 300 mg daily, for a 53kg female, the dose would be: 53 kg * 5 mg/kg = 265 mg
• Since 265 mg is not available, we should use the available dose, in this case 300 mg is the available dose and is higher than 265 mg. 2

From the Research

Weight-Based Dosage of ATT Therapy

The weight-wise dosage of ATT therapy for a 53kg female can be determined based on the recommended dosages of the essential anti-tuberculosis drugs.

• The World Health Organization (WHO) recommends the following dosages for adults:
  • Isoniazid: 5 mg/kg
  • Rifampicin: 10 mg/kg
  • Ethambutol: 15-20 mg/kg
  • Pyrazinamide: 20-25 mg/kg
  • Streptomycin: 15 mg/kg 3
• Based on these recommendations, the dosage for a 53kg female would be:
  • Isoniazid: 265 mg (53 kg x 5 mg/kg)
  • Rifampicin: 530 mg (53 kg x 10 mg/kg)
  • Ethambutol: 795-1060 mg (53 kg x 15-20 mg/kg)
  • Pyrazinamide: 1060-1325 mg (53 kg x 20-25 mg/kg)
  • Streptomycin: 795 mg (53 kg x 15 mg/kg)
• However, it's essential to note that the actual dosage may vary depending on individual factors, such as renal function, liver function, and other health conditions 4, 5, 6, 7

Factors Affecting Dosage

Several factors can affect the dosage of ATT therapy, including:

• Body weight: The dosage of ATT drugs is typically based on body weight, with higher weights requiring higher dosages 3, 4
• Renal function: Patients with renal impairment may require adjusted dosages of certain ATT drugs, such as streptomycin and ethambutol 3
• Liver function: Patients with liver impairment may require adjusted dosages of certain ATT drugs, such as isoniazid and rifampicin 3
• Pregnancy: Pregnant women may require adjusted dosages of certain ATT drugs, such as streptomycin, which is not recommended due to ototoxicity to the fetus 3
• HIV co-infection: Patients with HIV co-infection may require adjusted dosages of certain ATT drugs, such as rifampicin, which can interact with antiretroviral therapy 3