Treatment of TB Flashcards
What are the main criteria for anti-TB drugs?
- Intracellular activity (as bacteria multiply within macrophages)
- Combination therapy (to minimise long-term resistance)
- Low interaction with other TB agents
- Prolonged therapy
- Treats distinct TB populations (needs to treat all types of bacteria i.e. rapidly dividing, dormant, slowly dividing etc.)
How does Rifamipicin work?
It inhibits RNA polymerase
- therefore any metabolising cell will be affected
- Bactericidal
How does Isoniazid work?
- It reduces the synthesis of mycolic acids
- Bactericidal to rapidly growing cells, bacteriostatic to slow
- Pro-drug
- Distributes into CSF so can be used for extra pulmonary TB
How does Pyrazinamide work?
- It reduces the synthesis of mycolic acids
- Also damages the bacterial cell membrane
- Bactericidal
- Pro-drug
How does Ethambutol work?
It inhibits cell wall synthesis and so increases the permeability of the cell wall
- Bacteriostatic
What are the main side effects associated with Ethambutol?
- Optic neuritis
- Joint pain
- Should not be given to patients under 5
What are the main 2nd line drugs used in TB?
- Streptomycin (aminoglycoside)
- Capreomycin (aminoglycoside)
- Cycloserine - has neurological side effects
- Ciprofloxacin (quinolone)
- Azithromycin (macrolide)
How long are Rifampicin and Isoniazide used for in TB?
6-9 Months
How long are Pyrazinamide and ethambutol used for in TB?
Taken for the first 2 months of treatment
What are the 2 drugs taken for longest in TB treatment?
Rifampicin and Isoniazide
What is Multidrug Resistant TB (MDR-TB)?
Resistant to at least 2 first line drugs
What is Extremely Drug Resistant TB (XDR-TB)?
Resistant to at least 2 first line drugs and at least 3 of the 6 second line drugs
