anti-mycobacterial drugs Flashcards Preview

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Flashcards in anti-mycobacterial drugs Deck (30):
1

Which drugs are used to treat mycobacterial infections?

isoniazid
Pyrazinamide
ethambutol
rifampin/rifabutin
clofazimine
dapson

2

which drugs interfere with mycolic acid synthesis

isoniazid
pyrazinamide
ethambutol

3

which drugs interfere with DNA dependent RNA pol?

rifampin/rifabutin

4

which drug interferes with DNA template function

clofazimine

5

which drug inhibits DH synthase

dapsone

6

what is the treatment plan for M tuberculosis

6 month plan =
2 months isoniazid and rifampin, pyrazinamide
4 additional months isoniazid and rifampin

9 month plan =
isoniazid + rifampin

7

what is the treatment plan for M kansasii (pneumonia)

isoniazid + rifampin + ethambutol
treat until you have 12 months of negative sputum

8

what is the treatment plan for M avium complex (MAC) (pneumonia)

clarithromycin or azithromycin + ethambutanol +/- rifabutin

treat until six months after negative sputum

9

what is the treatment for M leprae

dapsone + rifampin +/- clofazimine
treatment for a min of 2 years

10

what is the treatment for M fortuitum

amikacin (aminoglycoside) + doxycycline (tetracycline)
4 months for cutaneous
6 months for bone
12 months for lungs

11

what is the treatment for M marinum

rifamin + ethambutol
3 months

12

isoniazid - mechanism

inhibits mycolic acid
bactericidal during long growth phase
bacteriostatic in resting organisms

13

what is mycolic acid?

a unique component of mycobacterial cell wall

14

isoniazid - side efects

hepatotoxicity (increases with age)
peripheral neuritis (B6 given for prevention)

15

pyrazinamide - mechanism

inhibits mycolic acid synthesis
bactericidal

16

proposed mechanism for inhibition of mycolic acid synthesis

target fatty acid synthase I gene

except ethambutol - inhibits use of mycolic acid in cell wall synth

17

pyrazinamide - side effects

dose related hepatits
should only be used for short therapy; monitor liver function

18

ethambutol - mechainsm

interferes with mycolic acid
- inhibits incorporation of mycolic acid into cell wall
-bacteriostatic

19

ethambutol - side effect

optical neuritis (visual acuity and red/green discrimination)
-dont use in children under 5

also rare side effect is gout due to inhibition of excretion of uric acid

20

ethambutol - excretion

renal
dose adjustment may be necessary - accumulation can happen in patients with impaired function

21

rifampin/rifabutin - mechanism

DNA dep RNA polymerase - inhibits

eukaryotic RNA pol is less sensitive to rifampin because of binding affinity differences so it is safe to use

22

rifampin/rifabutin - side effects

rifampin - substrate and inducer for CYP3A4
rifabutin is not as potent of an inducer

rifampin reduces HIV protease inhibitor levels by 80% - patients need to be switched to rifabutin (decreases by 20-40%)

also turns saliva, urine, tears orange-red

23

clofazimine - mechanismm

inhibits template function of DNA

(binds to DNA and inhibits function)

24

clofazimine - excretion

hepatic, to feces
little is excreted in the urine

25

clofazimine - side effect

brownish pink coloring of skin, cornea, urine

26

dapsone - mechanism

inhibits DH (dihydropterate) synthease
interferes in folic acid synthesis

dapsone is a sulfone so mechanism is like other sulfonamides

27

dapsone - side effect

similar to sulfonamides
-anorexia, nausea
-hemolytic anemia is rare but more frequent in individuals with G6PDH deficiency
-sulfone syndrome (rare)

28

which drugs cause hepatotoxicity?

isoniazid
pyrazinamid

29

which drug should you not use in pregnant patients?

clofazimine

30

which drug can cause hemolytic anemia in G6PDH deficient patients

dapsone