Lecture 3- quinolones, folic acid antagonists, urinary antiseptics Flashcards

1
Q

fluoroquinolones MOA

A

target DNA gyrase, primarily in gram neg bac and topoisomerase IV in gram pos bac to inhibit DNA replication

  • gyrase: intro negative supercoils into DNA to prevent excessive positive supercoiling
  • topo: promote separation of cms DNA into daughter cells
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2
Q

types of dna gyrase/topo inhibitor- fluoroquinolones (3)

A
  1. ciprofloxacin
  2. levofloxacin
  3. moxi
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3
Q

fluoroquinolones ROA

A

oral, IV, ophthalmic

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4
Q

fluoroquinolones clearance

A

renal, dose adjust

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5
Q

CIPROfloxacin indications

A
  • most active agaisnt gram neg strains and enteric coliforms eg. penicillin, cephalosporins
  • for travellers diarrhea
  • in skin, bone and joint infections
  • against P. aeruginosa
  • should be AVOIDED in MRSA infections
  • UTI but not first line (lower UTI mostly)
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6
Q

levo and moxi coverage

A
  • better covrage against gram POS org esp S. penumoniaea
  • better cov against atypical pathogens eg. mycoplasm
  • useful in resp infections
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7
Q

fluoroquinolones adverse effects

A
  • GI eg. diarrhea, nausea
  • C. diff colitis
  • headache dizziness
  • phototox
  • tendinitis
  • prolong QT interval
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8
Q

fluoroquinolones and tb

A

not as first line as they may mask sx of tb

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9
Q

fluoroquinolones CI

A

myasthenia gravis- may exacerbate muscle weakness

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10
Q

classes of folate syntehsis inhibitors (3)

A
  1. sulfonamides
  2. trimethoprim
  3. cotrimoxazole
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11
Q

sulfonamides MOA

A

competetive inhibitors of dihydropteroate synthase

bacteriostasis induced can be REVERsed by PABA

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12
Q

sulfonamides distri

A

bound to serum albumin

distri well throughout bodily fluids and penetrate well into CSF

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13
Q

sulfonamides elim

A

renal

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14
Q

sulfonamide clinical uses

A

combined with trimethoprim

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15
Q

sulfonamides adverse effects

A
  • crystalluria (form acetylated product which is toxic and ppt at neutral or acidic pH)
  • hypersen eg. rash
  • hemolytic anemia
  • kernicterus- CI in children (brain damage)
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16
Q

trimethoprim MOA

A

potent inhibitor of bacterial dihydrofolate reductase

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17
Q

trimethoprim resistance

A

in gram neg bacteria due to altered dihydrofolate reductase that has lower affinity for trimethoprim
efflux pumps

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18
Q

trimethoprim absorption

A

rapid absorption with ORAL admin
widely distri into body
godoCSF penetration

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19
Q

trimethoprim elim

A

renal, mostly unchanged

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20
Q

trimethoprim adverse efefct

A

FOLIC ACID deficiency

anemai, leukopenia

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21
Q

cotrimoxazole MOA

A

synergistic antimic activity with inhibitrion of two sequential steps

  • sulfamethoxaxole inhibits incorporation of PABA into difolate acid
  • trimeoprim prevents reduction of dihydrofolate to tetrathydrofoalte
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22
Q

cotrimoxazole ROA

A

oral commonly

IV also can

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23
Q

cotrimoxazole distribution

A

good CSF penetration, readiliy crosses BBB

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24
Q

cotrimoxazole clearance

A

excreted in urine

25
Q

what does cotrimoxazole contain?

A

sulfamethoxolate and trimethoprim

26
Q

cotrimoxazole uses

A

UTRI
resp tract infection
MRS and comm acquried skin and soft tissue infection penumocystis pneumonia caused by PNEUMOCYSTIS JIROVECI

27
Q

cotrimoxazole adverse

A

skin rxn eg. rash
photosen
nausea vomitting
megaloblastic anemia (folic acid ef)

28
Q

drug for urinary antiseptic (1)

A

nitrofurantoin

29
Q

nitrofurantoin use

A

lower UTI

30
Q

nitrofurantoin MOA

A

reduce drug to hgihly active intermediate that inhibits enzymes and disrupts synthesis of proteins, DNA, RNA

31
Q

nitrofurantoin spectrum

A

against e coli and enterococci

pos and neg

32
Q

nitrofurantoin ROA

A

oral

33
Q

nitrofurantoin absorption

A

rapidly from GIT

34
Q

nitrofurantoin distri

A

high urinary conc while limiting sytemic exposure

- high conc in urine fast–> lower systemic exposure of drug

35
Q

nitrofurantoin adverse

A

nausea, vomiting
leukpenia, hemolytic anemia
- hepatocellular damage
- pulmn toxicity for eledrly

36
Q

nitrofurantoin CI

A
  • imparied renal func
  • pregnant
  • infants <1 month
37
Q

classes of polymyxins (2)

A
  1. polymyxin B

2. colistin

38
Q

diff between polymyxin B and colistin

A

polymyxins B administered directly as active antibiotic vs colistin admin as inactive prodrug

39
Q

polymyxins MOA

A

bactericidal

disrupt structure of cell membrane phospholipid and increase cell permeability

40
Q

polymyxins spectrum of activity

A

NARROW spectrum, mainly gram NEG
used for multidrug resistant gram neg bac
not useful agaisnt atypical and gram POS

41
Q

polymyxins ROA

A

iv, inhalation

42
Q

polymyxins adverse

A

nephrotox

neurotox eg. confusion, hallucination

43
Q

fosfomycin spectrum

A

against wide range of gram POS and NEG

44
Q

fosfomycin MOA

A

interferes with cell wall synthesis

45
Q

fosfomycin MOA

A

interferes with cell wall synthesis

46
Q

advatnage / spectrum of fosfomycin

A

good against resistant bacteria

47
Q

fosfomycin uses

A

UTI

48
Q

fosfomycin ROA

A

rapid absorption with oral admin and is converted to fosfomycin
poor systemic absorption

49
Q

adverse effects of fosfomycin

A

GI, headache, vaginitis

50
Q

anti protozoal agents

A

protozoal infectiosn in underdev countires

unicellular eukaryotes- have met processes closer to those of human

51
Q

how to treat amebiasis

A

chemotherapy

  1. luminal- act on parasite in lumen
  2. systemic- in intestinal wall and liver
  3. mixed amebicides
52
Q

metronidazole MOA

A

serve as electron acceptor–> form cytotoxic free radicals that result in protein and DNA damage
metro stronger against ANAEROBES

53
Q

metronidazole absorption

A

complteley and rapidly absorbed after ORAL adin

54
Q

metronidazole distri

A

distri well into body and in CSF

55
Q

metronidazole elim and met

A

heptaic met- accum in pt with severe hep disease

elim- in urine

56
Q

metronidazole adverse

A

GI, unpleasant metallic tast

57
Q

metronidazole pregnancy usage

A

cat B

avoid in first trimester

58
Q

who not to give cirpofloxacin to

A

<18 yo– will hv joint problem

dont give for serious lower UTI, mostly for upper

59
Q

what to give for nail infections?

A

give orally- need to be absorbed systemically and accum at keratin
give azoles