Protein Synthesis Inhibitors - 50S Inhibitors

Question 1

what drugs are 50S inhibitors?

Answer 1

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

Question 2

what drugs are macrolides

Answer 2

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

Question 3

MOA of macrolides

Answer 3

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

tRNA is dissociated with ribosome

Question 4

what takes up macrolides?

Answer 4

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

Question 5

what is fidoxamicin used for

Answer 5

c diff only

Question 6

macrolides are bacteri—–

Answer 6

bacteristatic

Question 7

spectrum of macrolides

Answer 7

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

Question 8

what are macrolides used for

Answer 8

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

Question 9

how to treat CAP

Answer 9

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

Question 10

how do macrolides get resisted

Answer 10

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

Question 11

what is a less common causeof macrolide resistance

Answer 11

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

Question 12

what interferes with erythromycin absorption

Answer 12

the base is destroyed by acid and food interferes with absorption

Question 13

what does erythromycin penetrate

Answer 13

prostate (prostatitis)

Question 14

which drugs inhibit cypP450

Answer 14

1. erythromycin
2. clarithromycin
   NOT AZITHROMYCIN

Question 15

what occurs if erythromycin or azithromycin are given IV?

Answer 15

phlebitic

Question 16

ADE of macrolides

Answer 16

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

Question 17

what specific ADE does clarithromycin have

Answer 17

metallic taste, prolonged QT interval

Question 18

which drugs cause prolonged QT intervals>

Answer 18

1. erythromycin

2. clarithromycin

Question 19

MOA of chloramphenicol

Answer 19

bind reversibly to 50S subunit and inhibits peptide bond formation

Question 20

spectrum of chloramphenicol

Answer 20

broad spectrum

Question 21

drawback of chloramphenicol

Answer 21

is TOXIC

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

Question 22

what is gray baby syndrome

Answer 22

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

Question 23

kinetics of macrolides

Answer 23

CYP450 3A4 (may have drug interactions with this)

Question 24

what is chloramphenicol used in

Answer 24

serious rickettsial infections or rocky mountain spotted fever

Question 25

MOA of clindamycin

Answer 25

bind to 50S preventing translocation

Question 26

spectrum of clindamycin

Answer 26

``` COMMUNITY ACQUIRED MRSA gram+ some gram- anaerobes NOT C DIFF (causes Cdiff) ```

Question 27

what is clindamycin used in

Answer 27

anaerobic infections, skin/soft tissue infections with penicillin allergy, abscesses (above the belt anaerobic drug)

Question 28

what clears clindamycin

Answer 28

liver (so is safe in renal impairment)

Question 29

what is there a high risk in using clindamycin

Answer 29

c diff infections

Question 30

MOA of linezolid

Answer 30

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

Question 31

coverage of linezolid

Answer 31

gram+ including MRSA, VRE, and listeria

Question 32

linezolid is bacter----

Answer 32

bacteriostatic EXCEPT BACTERICIDAL against strep and clostridium perfringens

Question 33

what is linezolid bactericidal against

Answer 33

streptococci and clostridium perfringens

Question 34

ADE of linezolid

Answer 34

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

Question 35

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

Answer 35

thrombocytopenia

Question 36

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

Answer 36

irreversible peripheral neuropathy and optic neuritis

Question 37

what drug can inhibit monoamine oxidase?

Answer 37

linezolid so can cause serotonin syndrome if pt taking SSRI

Question 38

what drugs can interact with linezolid

Answer 38

sympathomimetics and serotonergics

Question 39

MOA mupirocin

Answer 39

inhibits isoleucine tRNA synthetase

Question 40

spectrum mupirocin

Answer 40

gram +

Question 41

use of mupirocin

Answer 41

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

Question 42

what can help eradicate MRSA colonization of the nares?

Answer 42

mupirocin

Question 43

what causes atypical pneumonia

Answer 43

mycoplasma, chlamydia, legionella

Question 44

which drugs are not used in pregnancy?

Answer 44

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)