Tuberculosis: Treatment and prevention 2 Flashcards
Rifampicin is metabolized where? and causes what?
Metabolism in the liver-causes autoinduction and potent enzyme induces
the elimination of rifampicin
Primary biliary faecal route
Rifampicin causes drug interaction with which drugs?
Drug-interactions with drugs
metabolised in the liver
* Oral contraceptives & progestin
implants (replace with injectable
contraceptives)
Rifampicin causes which colour of pigmentation to body fluids
Orange, red, brown
Explain the distribution of Isoniazid
wide including the CSF
where is isoniazid metabolised
Metabolism in the liver via acetylation (slow acetylators at greater risk of neurotoxicity)
The excretion of isoniazide
Inactive metabolites of isoniazid excreted in the urine
Neurotoxicity reversed by what?
Pyridoxine (B6)
Drug interactions of izoniazid
Drugs metabolised in the liver (weak enzyme inhibitors)
Caution of isoniazid in patient with what?
epilepsy
Explain the distribution, metabolis and excretion of ethambutol
Pharmacokinetics
* Distribution: wide not in CSF
* Metabolism in the liver up to
15%
* Mainly unchanged in the urine
Say the contra-indication and caution of ethambutol
- Contra-indications: optic neuritis
- Cautions: renal failure, in
children under 8 years (visual
symptoms difficult to assess),
hyperuricaemia
say one adverse effect of ethambutol
Ocular toxicity – patient selfmonitoring
(reading fine print),
monitor: colour discrimination
and visual field
Distribution of pyrazainamide
wide including CSF
In pyrazinamide, hepatotoxicity is what?
dose related
explain the cause of hyperuricaemia in pyrazinamide
Hyperuricaemia (caused by
decreased uric acid clearance)
associated with arthralgia (may
precipitate gout)
TB treatment otcomes
wanted vs unwanted
list them
Wanted
* Prevent TB transmission
* Cure with minimal problems
* Cure with chronic lung disease
Unwanted
* Transmission of TB
* MDR / XDR
* Death
List the seven Drug resistant TB categories
- Mono-resistant TB
- Poly-resistant TB
- MDR-TB
- Rifampicin resistant-TB (RR-TB)
- Resistance to at least rifampicin
- Extensively drug-resistant TB (XDR-TB)
- Pre-XDR-TB
Explain the MDR (multi DR)
MDR (multi DR)
* In vitro resistance to:
* Rifampicin
* Isoniazid
* With or without resistance to other
anti-TB drugs
Explain the XDR (extensively DR)
- MDR TB
- +
- In vitro resistance to:
- Any fluoroquinolone
- AND
- Any injectable drug
- Extremely difficult and expensive to
treat with a high mortality (90%) in
HIV co-infected patients
what are resistance test for Isoniazid resistance
Resistance tests:
* inhA mutation and
* katG mutation
explain the test of izoniazid resistance
- inhA mutation only (use high dose INH: 10mg/kg/day)
- katG mutation (use ethionamide)
- Complete resistance (both)
- Do not use INH or ethionamide
Differentiate the Drug-resistance TB treatment short regimens
Short regimen
Pre -2024 – old regimen being phased out:
* Short course:
* At least 6 drugs used for 9 months
2024 – new regimen being phased in:
* BPaL-L:
* At least 3 drugs used for 6 months
explain the long regimen in drug-resistant TB treatment regimens
Long regimen
* 18 months
* Complicated EPTB / extensive
disease on CXR
* Children < 6 years
* Hx of previous treatment with 2nd
line drugs for more than 1 month
* Contact with XDR / Pre-XDR
* Both INH mutations
differentiate between short course and new short cause- BPaL-L under drug resistant TB treatment short regimens
Short course
* 9 months
* Adults, pregnant women and
children ≥6 years (≥ 16kg)
New short course – BPaL-L
* 6 months
List the drugs for Drug-resistant TB treatment: BPaL-L (6 months)
-The 6-month BPaL-L regimen;
* Bedaquiline,
* Pretomanid,
* Linezolid (600 mg)
* With or without levofloxacin (if sensitive)
List drugs for drug-resistant TB treatment: long course
Core drugs:
* Bedaquiline,
* Linezolid
* Levofloxacin (substitute if fluoroquinolone resistance)
* Clofazimine
* Terizidone
* Co-administer pyridoxine (50mg for adults, 25 mg to children) to
prevent peripheral neuropathy due to terizidone
List drugs for children for drug-resistant TB treatment:long course
Children:
* Bedaquiline ≥6 years is safe for use
Substitute bedaquiline for:
* Delamanid (3 to 6 years)
* Para-aminobenzoic acid (less than (<)3 years)
