inhibitors of protein synthesis I

Question 1

prokaryotic ribosomes are composed of what two subunits

Answer 1

• 50S
• 30S
• combine to form 70S total

Question 2

Eukaryotic ribosomes are composed of what two subunits

Answer 2

• 60S
• 40S
• combine to form 80S

Question 3

MOA of macrolides

Answer 3

targets 50S subunit of ribosome

Question 4

Macrolides prototype

Answer 4

erythromycin

Question 5

Name the three macrolides

Answer 5

1. erythromycin
2. clarithromycin
3. azithromycin

Question 6

route of administration of erythromycin

Answer 6

oral, IV

Question 7

route of administration of Clarithromycin

Answer 7

oral

Question 8

route of administration of azithromycin

Answer 8

oral, IV

Question 9

are macrolides bacteriostatic or cidal

Answer 9

bacteriostatic; concentration/organism dependent- cidal activity

Question 10

coverage of macrolides

Answer 10

G+

*majority of G- organisms are resistant

Question 11

how do bacteria become resistance to macrolides

Answer 11

• efflux pumps
• methylation of drug binding site (ribosome)

Question 12

toxicity of macrolides, particularly Erythromycin

Answer 12

• diarrhea
  
  • erythromycin +++; Azithro ++; clarithromycin +: GI adverse effects
• QT prolongation
  
  • erythro +++; Claritho ++; Azithro +

Question 13

erythromycin is a potent inhibitor of what enzyme that leads to drug interactions

Answer 13

CYP3A4

• therefore, can inhibit the hepatic metabolism of other drugs that require CYP3A4, increasing their serum concentrations and potentially causing toxicity

Question 14

DOC for urogenital infections due to Chlamydia occuring during pregnancy

Answer 14

Erythromycin

Question 15

DOC legionnaries’ disease

Answer 15

azithromycin

Question 16

MOA of Ketolides

Answer 16

block bacterial protein synthesis; has 2 binding sites for the ribosomal RNA, 50S, which increases its affinity

Question 17

what group is Telithromycin in

Answer 17

Ketolides

Question 18

coverage of Telithromycin

Answer 18

broad spectrum

• good against respiratory pathogens including erythromycin and penicillin resistant pneumococci: remains on market for community acquired PNA (not first choice)

Question 19

route of administration of Telithromycin

Answer 19

oral

Question 20

metabolism of Telithromycin

Answer 20

via CYP3A4

Question 21

toxicity of Telithromycin

Answer 21

• diarrhea
• hepatotoxicity

Question 22

MOA of Clindamycin

Answer 22

binds to 50S ribosomal subunit

Question 23

coverage of Clindamycin

Answer 23

• aerobic G+
• Anaerobic G- and G+ organisms

Question 24

is Clindamycin bacteriostatic or cidal

Answer 24

either, depends on

• concentration at the site of action
• specific susceptibility of the organism

Question 25

why is Clindamycin used to treat osteomyelitis

Answer 25

it obtains high concentration in bones

Question 26

which organisms are extremely susceptible to Clindamycin

Answer 26

1. streptococci (except enterococci) and staphylococci (**MRSA**)

Question 27

what two Abx are used to treat toxic shock syndrome

Answer 27

* clindamycin * vancomycin

Question 28

Clindamycin toxicity

Answer 28

* **Pseudomembranous colitis** (overgrowth of clostridium difficile)

Question 29

is Clindamycin safe to use in nursing mothers

Answer 29

NO, crosses the placenta readily and is distributed into breast milk

Question 30

What two Abx does Streprogramins consist of

Answer 30

* **Dalfopristin** * **Quinupristin** * Trade name (Synercid) * combination is _bactericidal_

Question 31

MOA of Dalfopristin; Quinupristin (Synercid)

Answer 31

both Abx bind to 50S particles but inhibit different stages of protein synthesis

Question 32

route of adminstration of Dalfopristin; Quinupristin (Synercid)

Answer 32

IV infusion

Question 33

Dalfopristin; Quinupristin (Synercid) has been approved for what uses

Answer 33

* Aerobic G+ * penicillin resistant S. pneumoniae * complicated skin infections due to staph aureus (MSSA and MRSA) * vancomycin resistant Enterococcus faecium

Question 34

adverse reactions of Dalfopristin; Quinupristin (Synercid)

Answer 34

* hepatotoxicity * inhibit P450 drug metabolism system (CYP3A4), many metabolic interactions (warfarin, diazepam)

Question 35

what group does Linezolid belong to

Answer 35

Oxazolidinones

Question 36

coverage of Linezolid

Answer 36

aerobic G+ organisms * bacterial PNA * vancomycin-resistant enterococcal infections * MRSA \*\*\*new Abx; should be used as _alternate_ agent bc overuse with hasten selection of resistant strains

Question 37

MOA of Linezolid

Answer 37

* binds to a site on the bacterial **23S ribosomal RNA of the 50S** subunit

Question 38

Linezolid adverse reactions

Answer 38

reversible, non-selective inhibitor of monoamine oxidase (MAO) \*MAO inactivate neurotransmitters

Question 39

route of administration of Linezolid

Answer 39

IV or oral \*Oral bioavailability is 100%