TB

Question 1

Dose of isoniazid for latent TB

Answer 1

5mg/kg PO OD (max 300mg) 9 mths

Question 2

Dose of rifampicin for latent TB

Answer 2

10mg/kg PO OD (max 600mg PO OD) 4 mths

Question 3

For the treatment of active TB, before moving on from the intensive phase to the continuation phase, what must be done/observed?

Answer 3

Either:
- Confirmed susceptibility of TB to RIF and INH
OR
- Culture negative pulmonary TB

Question 4

What are the TB drugs and what to monitor for each of them?

Answer 4

R,I,P: Hepatotoxicity

E: Visual Toxicity

Question 5

Risk factors for hepatotoxicity when taking RIP?

Answer 5

1. Age > 35yo
2. Female
3. Underlying liver disease
4. Concurrent alc use
5. HIV

Question 6

What patients taking E should we monitor for visual acuity and colour discrimination tests, and how frequently should we monitor?

Answer 6

1. EMB Doses > 25mg/kg (wrong dose)
2. EMB taking for more than 2 months
3. Renal insufficiency

Monitor monthly

Question 7

What are some ways to differentiate pneumonia and TB?

Answer 7

1. Duration of sx:
   - TB: Gradual onset over weeks to months
   - Pneumonia: Acute onset, over hours to days
2. Chest XR
   - TB: Infiltrates in apical (upper) region of lung
   - Pneumonia: Infiltrates in lower lobes
3. TB classic sx: Night sweats and Hemoptysis

Question 8

Things that need to be done if someone diagnosed with TB:

Answer 8

Mandatory reporting to national tuberculosis registry

Question 9

Standard 6 mth treatment for active TB:

Answer 9

1. Intensive phase (2 mths):
   rifampicin 10mg/kg OD (600mg max) – 100/300mg tabs
   isoniazid 5mg/kg OD (300mg max) – 150/300mg tabs
   pyrazinamide 15mg/kg (2g max) – 500mg tabs
   ethambutol 15mg/kg (1600mg max) – 100-400mg tabs
   streptomycin 15mg/kg (1g max) – 1g vials
2. Continuous phase (4 mths):
   rifampicin 10mg/kg OD (600mg max) – 100/300mg tabs
   isoniazid 5mg/kg OD (300mg max) – 150/300mg tabs

Question 10

9 mth treatment for active TB:

Answer 10

1. Intensive phase (2 mths):
   rifampicin 10mg/kg OD (600mg max) – 100/300mg tabs
   isoniazid 5mg/kg OD (300mg max) – 150/300mg tabs
   ethambutol 15mg/kg (1600mg max) – 100/400mg tabs
2. Continuous phase (7 mths):
   rifampicin 10mg/kg OD (600mg max) – 100/300mg tabs
   isoniazid 5mg/kg OD (300mg max) – 150/300mg tabs

Question 11

Metabolism related things to take note of:

Answer 11

INH inhibits CYP enzymes

RIF induces CYP enzymes

Question 12

Singapore TB elimination programme:

Answer 12

promotion of direct observed therapy
national treatment surveillance registry
contact investigations