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PR3124 CA1 > Lecture 2- bacterial protein synthesis inhibitors > Flashcards

Lecture 2- bacterial protein synthesis inhibitors Flashcards

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1
Q

what are the types of 30S protein synthesis inhibitors? (3)

A
  1. tetracyclins
  2. glycylcycline
  3. aminoglycosides
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2
Q

types of 50s protein synthesis inhi (3)

A
  1. macrolides
  2. clindamycin
  3. linezolid
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3
Q

tetracycline MOA

A

enter organism via passive diffusion and transport protein mech (energy dep)
concentrate intracellularly in susceptible org
drug binds reversibly to 30s subunti of bacterial ribosome–> prevent binding of tRNA to A site of complex–> inhibit bacterial protein synthesis

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4
Q

tetracycline absorption? ROA

A

good bioavail
best on empty stomach
oral

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5
Q

what decreases tetracycline absorption? (2)

A
  • dairy prod

- containing divalent and trivalent cations

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6
Q

properties of tetracycline (3)

A
  • bacteriostatic ab
  • activity against broad spectrum of gram pos, gram neg and atypical bacteria and spirochete bac
  • inadequate activity against ps. aeruginosa and proteus
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7
Q

types of tetracycline (3)

A
  1. tetracycline
  2. doxycycline
  3. minocycline
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8
Q

tetracycline elimination

A

by kkdney

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9
Q

doxycycline elim

A

largerly excreted unchanged in bile and urine

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10
Q

minocycline elim

A

extensively met by liver before excretion

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11
Q

type of glycylcycline (1)

A

tigecycline

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12
Q

benefits of glycylcycline over tetra (2)

A
  • expanded spectrum of act

- decreased susceptibility to dev of resistance

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13
Q

what are the mechs of tetracyline resistance glycylcycline is designed to overcome? (2)

A
  • resistance mediated by acquired efflux pump

- ribosomal protection

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14
Q

tigecycline MOA

A

bind to bac 30s ribosome–> block entry to tRNA (similar to minocycline)

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15
Q

why does tigecycline have lower sus to resistance?

A

it has good binding affinity to ribosomes so its less likely to be dislodged by TET O and TET M proteins

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16
Q

ROA of tigecycline

A

IV- poor oral bioavail

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17
Q

tigecycline distribution?

A
  • penetrates well into tissue but low plasma conc

- poor option for bloodstream infection

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18
Q

tigecycline elim?

A

biliary/fecal

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19
Q

what is the spectrum of tigecycline

A
  • MRSA
  • multidrug resistant streptococci
  • vancomycin resistant enterococci
  • extended spectrum beta lactamase gram neg bac
  • community acquired pneumonia
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20
Q

tigecycline and tetra SE (4)

A
  • gastric discomfort
  • effects of calcified tissues- discolouration of teeth eg. grey, temporary stunting of growth
  • hepatotoxicity
  • ## phototoxicity
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21
Q

tigecycline and tetra CI (2)

A
  • pregnant

- < 8yo- may cause permanent teeth discolouration

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22
Q

types of aminoglycosides (5)

A
  • gentamicin
  • streptomycin
  • tobramycin
  • amikacin
  • neomycin
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23
Q

aminoglycosides MOA

A

distort structure of ribosom by binding to them and blocking formation of initiation complex, cause misreading of codons, inihibit translocation

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24
Q

aminoglycosides absorption and ROA

A

poor oral bioavail– parenteral

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25
aminoglycosides clearance
renal, need dose adjustt
26
which drug has post antibiotic effect (PAE)?
aminoglycosides
27
what is PAE
even tho drug conc has dropped below MEC, can still see effect mainly coz drug has doen something to bacteria and this bacteria needs to recover
28
antimicrobial spectrum of aminoglycosides
- broad spectrum | - primarily effective against aerobic gram neg and mycobacteria
29
wat is aminoglycosides used in combi with | why?
beta lactams for therpay of proven or suspected bacterial infections - expand spectrum of activity of antimic - provide synergistic bacterial killing - prevent emergence of resistance to indv agents
30
gentamycin indicatiosn
- for serious gram neg bac infection - more active against gram POS cocci than others when used with betalactam - combi therapy with penicillin/ceftriaxone to treat enterobacteriaceae
31
tobramycin indication
- pseudomonas aeruginosa
32
amikacin indication
- WIDEST spcetrum | - ineffective against majority gram POS
33
neomycin ROA
oral, topical
34
neomycni indication
- toxic - topcial against skin infections - oral for bowel prep for surgery
35
aminoglycosides adverse effects
- ototoxicity- hearing - nephrotox- retention of aminoglycosides by proximal tubular cells - neuromuscular paralysis - hypersen
36
6 NOs of aminoglycosides
1. no to protein synthesis- inhibit 30s 2. mainly aerobic gram Neg Org 3. No to use during pregnancy 4. No to CSF penetration 5. Nephro and Oto toxicity 6. No to oral admin
37
factors that predispose nephro and oto toxicity
- dose - duration - concomitant use of nephrotoxic drugs - elderly
38
resistance to aminoglycosides
- increase efflux pumps reduce effective intracellular conc - gram neg bacteria produce aminoglycosides inactivating enzymes - some bacteria alter 30s rib subunit - low level resistance may result from inhibition of aminoglycosides uptake by bacteria
39
types of macrolides (3)
- erythromycin - clarithromycin - azi
40
classes of 50s inhibitors (3)
1. macrolides 2. clindamycin 3. linelozoid
41
macrolides MOA
inihibit protein synthesis by reversibly binding to 50s subunut inhibit translocation
42
benefits of clari and azi over erythro
- imrpoved acid stability, tissue penetration, braoden spectrum of activity
43
macrolides ROA
oral and parenteal | good oral bioavail
44
macrolides indications
ATYPICAL microbes
45
macrolides SE (3)
- gastric distress and motility - hepato - oto - prolong QT interval
46
erythromycin ROA
oral, IV
47
erythromycin indication
against gram pos and neg treat comm acquired pneumonia effective against atypical
48
clarithromycin ROA
oral
49
clarithromycin indication
most active against both pos and neg | higher activity against atypical bac
50
benefit of clarithromycin
modified for better GI tolerance compaed to ery | - clari and azi stable in stomach acid and are readily absorbed
51
azithromycin ROA
oral, IV
52
azithromycin indication
most avtive against resp infections
53
macrolide elim
metabolised hepatically
54
disad of macrolides
poor CSF penetration, not good for CNS infection
55
macrolides CI
hepatic dysfunction
56
macrolides resistance- how is it acquired (2)
- acquire oen of a erm gene resulting in ribosomal methylation, reduced binding of macrolides to 50s rib subunit - increased expression of efflux pump
57
what class does clindamycin belong in
lincosamide
58
clindamycin indication
anaerobic infection
59
clindamycin moA
bind exclusively to 50s subunit of bacterial ribosome and inhibit peptide synthesis
60
clindamycin indications
- trat infection caused by gram pos including MRSA and streptococcus and penicillin resistance anaerobic bac - good spectrum of activity agaisnt oral pathogens
61
what cant clindamycin be used against
CDAD | coz it has high risk for CDAD
62
clindamycin ROA
IV, oral | good oral bioavail
63
clindamycin distribution
well into fluids | poor entry into CSF
64
clindamycin metabolism
hepatic
65
clindamycin adverse effects
takew ith full glass of water to reduce esophageal irritaiton. do not lie down immediately skin rash CDAD
66
linezolid MOA
bidn to bac 23s ribosomal RNA of 50s subunit--> prevent formation of func 70s initiation complex
67
antimicrobial activity of linezolid
bactericidal - against gram pos - NOT FOR gram neg wide coverage due to uniqe MOA eg. covers penicillin resistant strains...
68
linezolid ROA
IV, oral
69
linezolid distribution
widely distri to body | good penetration into CSF and brain tissue
70
pro (2) and cons (2) of linezolid
pros 1. useful agaisnt many multidrug resistant strains 2. can give oral and IV, outpt cons 1. need give over longer period 2. need to monitor and take blood count
71
linezolid adverse
- GI eg. nausea - bone marrow suppression- monitor blood count - serotonin syndrome if given with selective serotonicn reuptake inhibitors

PR3124 CA1 (5 decks)

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