Inhibitors of Nucleic Acid Function 
or Synthesis Flashcards

1
Q

What do topoisomerases do?? how do they act?

A
Topoisomerase: A class ofenzymes that alter the supercoiling of double-stranded DNA. 
The topoisomerases act by transiently cutting one or both strands of the DNA.
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2
Q

name the four generations of fluoroquinolones

A
1st gen - nalidixic acid, neggram
2nd gen -
 ciprofloxacin (cipro), norfloxacin (noroxin), ofloxacin (floxin)
3rd gen - levofloxacin (levaquin)
4th gen - moxifloxacin (avelox)
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3
Q

what is the MOA if fluoroquinolones

A

they enter by passive diffusion through porins. inhibit replication of bacterial DNA by interferring with bacterial DNA gyrase (topoisomerase 2) during replication. they bind to both enzyme and DNA forming a complex leading to cell death by DNA cleavage.

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4
Q

fluoroquinolones are bacteriostatic. t/f?

A

false. they are bactericidal.

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5
Q

which gram - organims are fluoroquinolones effective against?

A

enterobacteria, moraxella cattrhalis, pseudomonas, legionella, haemophilus influenzae, chlamydia, mycobacteria

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6
Q

fluoroquinolones are effctive in ___________ but not __________.

A

gonorrhoea but not syphilis

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7
Q

which fluoroquinolones has activity against streptococcus pneumoniae

A

levofloxacin

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8
Q

which fluoroquinolone is used to reduce the incidence of post surgical UTI

A

levofloxacin

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9
Q

2nd gen fluoroquinolones are addtionally active against which atypical organisms?

A

chlamydia/mycoplasma pneumoniae

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10
Q

1st gen fluoroquinolones use is restricted to ttt of?

A

uncomplicated UTI

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11
Q

what are the therapeutic indications of ciprofloxacin

A

prophylaxis against G- in nuetropenic patients
w aminoglycosides for ttt of febrile neutropenia
meningitis prophylaxis and carrier (hajj season)
for multi drug resistant TB

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12
Q

name the most commonly used fluoroquinolone

A

ciprofloxacin

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13
Q

typical therapeutic applications of ciprofloxacin

A

respiratory infections, UTI, gastric infections, anthrax, gonorrhea

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14
Q

norfloxacin is used to treat?

A

complicated and uncomplicated UTI and prostatitis

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15
Q

is norfloxacin used to treat systemic infections. why?

A

No because it is only concentrated in the urine

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16
Q

uses of levofloxacin

A

prostatitis due to ecoli and STD

17
Q

which STD is levofloxacin not effective against

18
Q

levofloxacin has excellent activity against

a. respiratory infections
b. syphilis
c. diarhhea

A

respiratory infections due to streptoccocus penumoniae

19
Q

what are the reasons for resistance of fluoroquinolones

A

altered target : mutations in DNa gyrase and topoisomerase IV
decreased accumulation : decreased porins and decreased drug (efflux pump)

20
Q

the absoprtion of fluoroquinolones is decreased by

A

antacids al3+ and mg2+

diet containing calcium and zinc

21
Q

fluoroquinolones accumulate in __________ and __________.

A

macrophages and leukocytes.

22
Q

the following is NOT an adverse reaction of fluoroquinolones

a. nephrotoxicity
b. phototoxicity
c. ototoxicty
d. CNS problems

A

c. ototoxicity

23
Q

caution must be taken with fluoroquinolones in CNS problems such as __________.

24
Q

name a drug that inteferes with th metabolism of fluoroquinolones

A

cimetidine

25
ciprofloxacin and ofloxacin inhibit the metabolism of which 2 drugs
theophylline and warfarin
26
Microorganisms commonly complicating UTI include:
E. coli (80% of cases) Staphylococcus saprophyticus Klebsiella pneumoniae Proteus mirabilis
27
urinary tract antiseptics achieve concentrated levels in the systemic circulation. t/f
false. they concentrate only in the urine
28
in methenamine decomposition to __________ occurs at ____ pH.
formaldehyde, low pH
29
methenamine is used to treat _______ but not _______.
lower UTI but not upper UTI
30
methenamine is a. bacteriostatic b. bactericidal
a. bacteriostatic
31
how can the effect of methenamine be increased
Higher activity in acidic urine, ascorobic acid and cranberry can be given to lower urine pH
32
methenamine is contraindicated in
renal insufficiency
33
what is the MOA of nitrofurantoin
susceptible bacteria reduce it to an acive agent that inhibits enzymes and damages DNA
34
nitrofurantoin is methenamine is a. bacteriostatic b. bactericidal
a. bacteriostatic
35
adverse effects of nitrofurantoin and methenamine
``` nitrofurantoin GI disturbances hemolytic anemia in G6PD neurological problems methenamine : albuminuria, hematuria, GI disturbances ```