Protein Synthesis Inhibitors - 50S Inhibitors Flashcards

1
Q

what drugs are 50S inhibitors?

A
  1. macrolides
  2. chloramphenicol
  3. clindamycin
  4. erythromycin (macrolides)
  5. linezolid
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2
Q

what drugs are macrolides

A
  1. azithromycin
  2. clarithromycin
  3. erythromycin
  4. fidoxamicin
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3
Q

MOA of macrolides

A

bind irreversibly to 50S near peptidyltransferase center, so transpeptidation is prevented by blocking the polypeptide exit tunnel.

tRNA is dissociated with ribosome

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4
Q

what takes up macrolides?

A

leukocytes take up macrolides so they are delivered to the site of infection

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5
Q

what is fidoxamicin used for

A

c diff only

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6
Q

macrolides are bacteri—–

A

bacteristatic

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7
Q

spectrum of macrolides

A
  1. gram+
  2. gram-
  3. intracellulars
  4. h pylori
  5. atypical pneumonia like mycoplasma pneumonia
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8
Q

what are macrolides used for

A

respiratory tract infections like URI, acute otitis media, and community acquired pneumonia

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9
Q

how to treat CAP

A

give macrolide (cover mycoplasma pneumo) with 3rd generation cephalosporin (will cover strep pneumo)

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10
Q

how do macrolides get resisted

A
  1. modification of ribosomal binding site by mutation or methylation leading to inhibition of macrolide binding
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11
Q

what is a less common causeof macrolide resistance

A
  1. reduced permeability of cell membrane
  2. active efflux
  3. production of esterases that hydrolyze macrolides (enterobacteriaceae)
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12
Q

what interferes with erythromycin absorption

A

the base is destroyed by acid and food interferes with absorption

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13
Q

what does erythromycin penetrate

A

prostate (prostatitis)

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14
Q

which drugs inhibit cypP450

A
  1. erythromycin
  2. clarithromycin
    NOT AZITHROMYCIN
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15
Q

what occurs if erythromycin or azithromycin are given IV?

A

phlebitic

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16
Q

ADE of macrolides

A
  1. agonsts of motilin receptor – profund diarrhea and cramping no matter how much food you eat
  2. ototoxicity
  3. phlebitic (IV)
  4. hepatotoxic
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17
Q

what specific ADE does clarithromycin have

A

metallic taste, prolonged QT interval

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18
Q

which drugs cause prolonged QT intervals>

A
  1. erythromycin

2. clarithromycin

19
Q

MOA of chloramphenicol

A

bind reversibly to 50S subunit and inhibits peptide bond formation

20
Q

spectrum of chloramphenicol

A

broad spectrum

21
Q

drawback of chloramphenicol

A

is TOXIC

  1. gray baby syndrome
  2. anemia
  3. aplastic anemia
  4. drug interactions
22
Q

what is gray baby syndrome

A

babies lack glucuronidine transferase, so chloramphenicol accumulates and affects mitochondria leading to acidosis, gray color and death

23
Q

kinetics of macrolides

A

CYP450 3A4 (may have drug interactions with this)

24
Q

what is chloramphenicol used in

A

serious rickettsial infections or rocky mountain spotted fever

25
Q

MOA of clindamycin

A

bind to 50S preventing translocation

26
Q

spectrum of clindamycin

A
COMMUNITY ACQUIRED MRSA 
gram+
some gram-
anaerobes 
NOT C DIFF (causes Cdiff)
27
Q

what is clindamycin used in

A

anaerobic infections, skin/soft tissue infections with penicillin allergy, abscesses

(above the belt anaerobic drug)

28
Q

what clears clindamycin

A

liver (so is safe in renal impairment)

29
Q

what is there a high risk in using clindamycin

A

c diff infections

30
Q

MOA of linezolid

A

binds to 50S to prevent formation of 70S initiation complex

31
Q

coverage of linezolid

A

gram+ including MRSA, VRE, and listeria

32
Q

linezolid is bacter—-

A

bacteriostatic EXCEPT BACTERICIDAL against strep and clostridium perfringens

33
Q

what is linezolid bactericidal against

A

streptococci and clostridium perfringens

34
Q

ADE of linezolid

A
  1. HA
  2. thrombocytopenia (if given more than 2weeks)
  3. irreversible peripheral neuropathy and optic neuritis if more than 28days
  4. inhibits monoamine oxidase activity – serotonin syndrome in pt with SSRI
35
Q

what occurs if linezolid is given for more than 2 weeks?

A

thrombocytopenia

36
Q

waht occurs if linezolid is given for more than 28days?

A

irreversible peripheral neuropathy and optic neuritis

37
Q

what drug can inhibit monoamine oxidase?

A

linezolid so can cause serotonin syndrome if pt taking SSRI

38
Q

what drugs can interact with linezolid

A

sympathomimetics and serotonergics

39
Q

MOA mupirocin

A

inhibits isoleucine tRNA synthetase

40
Q

spectrum mupirocin

A

gram +

41
Q

use of mupirocin

A

topical only for impetigo or eradication of MRSA colonization in the nares

42
Q

what can help eradicate MRSA colonization of the nares?

A

mupirocin

43
Q

what causes atypical pneumonia

A

mycoplasma, chlamydia, legionella

44
Q

which drugs are not used in pregnancy?

A
  1. sulfonamides (kernicterus)
  2. aminoglycosides (ototoxicity - cross placenta, accumulate in fetal plasma and amniotic fluid)
  3. fluroquinolones (cartilage damage)
  4. clarithromycin (embryotoxic)
  5. tetracycline (inhibit bone growth, discolor teeth chelation)
  6. griseofulvin (teratogenic)
  7. chloramphenicol (gray baby)