After completing a 2‑month intensive phase of isoniazid, rifampicin, pyrazinamide, and ethambutol for tuberculous cervical lymphadenitis, what is the appropriate continuation phase regimen, dose, duration, and monitoring for a 12‑year‑old boy weighing 47 kg?

Continuation Phase Treatment for Tuberculous Cervical Lymphadenitis in a 12-Year-Old

After completing the 2-month intensive phase of HRZE, this 12-year-old boy (47 kg) should receive isoniazid and rifampicin for an additional 4 months, completing a total 6-month treatment course for tuberculous cervical lymphadenitis. 1, 2, 3

Specific Drug Dosing for This Patient (47 kg)

Daily Regimen (Preferred)

• Isoniazid: 300 mg daily (approximately 6.4 mg/kg) 4, 3
• Rifampicin: 450 mg daily (approximately 9.6 mg/kg, as patient is <50 kg) 4, 2
• Pyridoxine: 10 mg daily supplementation should be added 1, 5

Alternative Thrice-Weekly Regimen (if directly observed therapy is used)

• Isoniazid: 600 mg (approximately 12.8 mg/kg, within the 15 mg/kg thrice-weekly range) 4, 3
• Rifampicin: 600 mg thrice weekly 4, 2

Critical Treatment Duration Considerations

The standard 6-month total duration (2 months intensive + 4 months continuation) is appropriate for lymph node tuberculosis in this case. 6, 2, 3 While some guidelines suggest extending treatment to 12 months for certain forms of extrapulmonary TB (particularly spinal TB in children), tuberculous lymphadenitis typically responds well to the standard 6-month regimen. 1, 5

The patient has already demonstrated excellent clinical response (fever resolved, pain subsided, lymph nodes regressing), which supports continuing with standard-duration therapy rather than extending to 9-12 months. 6, 5

Essential Monitoring Requirements

Clinical Monitoring

• Monthly clinical assessment to evaluate lymph node size, presence of fever, and general well-being 6
• Weight monitoring monthly to adjust dosing if the patient crosses the 50 kg threshold (would require rifampicin increase to 600 mg daily) 4

Laboratory Monitoring

• Baseline liver function tests (AST, ALT, bilirubin, alkaline phosphatase) should have been obtained before starting treatment 6
• Monthly liver function monitoring during continuation phase, or immediately if symptoms of hepatitis develop (vomiting, abdominal pain, jaundice) 6, 7
• Stop all hepatotoxic drugs immediately if AST/ALT rises to >5 times normal or if bilirubin rises 1
• Visual acuity monitoring is no longer needed as ethambutol has been discontinued after the intensive phase 6

Treatment Adherence

• Directly observed therapy (DOT) is strongly recommended throughout the continuation phase to ensure adherence and prevent drug resistance 6, 1, 2
• Monthly pill counts if DOT is not feasible 6

Common Pitfalls to Avoid

Dosing Errors

• Never use simple mg/kg calculations without checking weight-banded tables, as this can lead to underdosing or overdosing 4
• Do not continue pyrazinamide beyond 2 months in drug-susceptible TB, as prolonged use increases hepatotoxicity without additional benefit 1, 4, 7
• Do not continue ethambutol into the continuation phase for drug-susceptible TB once susceptibility is confirmed 6, 2

Duration Mistakes

• Do not routinely extend treatment to 9-12 months for lymph node TB unless there are specific complications (such as CNS involvement, spinal involvement, or treatment failure) 1, 5
• Do not stop treatment prematurely even if clinical improvement is dramatic; complete the full 6-month course 2, 3

Monitoring Failures

• Do not wait for routine monitoring if hepatitis symptoms develop; check liver function immediately and stop hepatotoxic drugs if indicated 6, 7
• Do not add a single drug to a failing regimen, as this promotes drug resistance 6, 8

Treatment Interruption Management

If interruptions occur during the continuation phase:

• Short interruptions (<14 days): Continue the regimen as originally planned 6
• Longer interruptions (≥14 days): Consider restarting the entire treatment course, particularly if the interruption occurs early in the continuation phase 6
• Continuous treatment is critical to prevent emergence of drug resistance 6, 2

Special Considerations for This Case

This patient's initial failure to respond to antibiotics (amoxicillin-clavulanate) followed by excellent response to ATT confirms the diagnosis of tuberculous lymphadenitis. The negative aspirate for tuberculosis but positive imaging findings (USG neck and CT chest suggestive of lymph node TB) represent a common diagnostic scenario where empiric treatment based on clinical and radiographic findings is appropriate. 6, 5

The decision to stop therapy should be based on the number of doses taken within the maximum treatment period, not simply a 6-month calendar period. 6 For daily therapy, this means approximately 180 doses total (60 doses intensive phase + 120 doses continuation phase). 6