Antimycobacterial Flashcards Preview

Pharmacology > Antimycobacterial > Flashcards

Flashcards in Antimycobacterial Deck (22):
1

What is the mechanism of action of isoniazid

inhibits synthesis of mycolic acid

2

How is isoniazid metabolized

prodrug activated in the mycobacteria by KatG to enzyme inhibitor
Metabolized by NAT2 in the liver (fast and slow acetylators)

3

Is isoniazid bacteriostatic or bacteriaicidal?

static in quiescent bacilli and cidal in active bacilli

4

What is the half-life of izoniazid

1 hr in rapid acetylators, 3 hrs in slow acetylators

5

Adverse effects of izoniazid

20% peripheral neuropathy, can be reduced by vitamin B6
8% in patients over 65 hepatotoxicity

6

What is the most common TB drug

Rifamycins-rifampin (also used for other bacterial infections)

7

What is the MOA of rifampin

inhibitor of RNA polymerase

8

Is rifampin static or cidal

cidal

9

Therapeutic uses of rifampin (3)

1) in combo with isoniazid for TB
2) Leprosy
3) broad spectrum antibiotic

10

Adverse reactions to rifampin

1) cholestatic jaundice and hepatitis (rare)
2) discoloration of body fluids- red-orange color
3) inducer of CYP isoforms

11

What is the MOA of ethambutol

inhibits arabinosyl transferase III, bacteriostatic

12

Therapeutic use of ethambutol

in combo for TB only

13

Adverse effect of thembutol

optic neuritis

14

Pyrazinamide MOA

prodrug converted to pyrazinoic acid (POA) by mycobacterial pyrazinamidase, bactericidal, target unknown

15

Therapeutic use of pyrazinamide

Sterilizing agent

16

Adverse effects of pyrazinamide

Hepatotoxicity
Hyperuricemia (gout)

17

Which TB drug is associated with the worst hepatotoxicity

isoniazid, has actually been fatal

18

What is prophylactic therapy for TB

one drug- isoniazid, rifampin

19

Treatment of active infection

guided by drug sensitivity screen

20

What are the phases of therapy for active TB

1) induction phase- eliminates active mycobacteria and renders non-infection
2) Continuation phase- eliminates intracellular "persisters"

21

What are drugs used in induction phase

INH, rifampin, and pyrazinamide then INH and rifampin for 4 months
Ethambutanol or streptomycin for resistance to INH

22

Which drugs are used in the continuation phase

intermittent therapy with INH and rifampin
Directly observed therapy is the standard of care