protein synthesis inhibitors

Question 1

protein synthesis inhibitors act by

Answer 1

inhibiting protein synthesis at either 30 s or 50s ribosomal site

*** which exploits the structural differences between eukaryotic and prokaryotic ribosomes

Question 2

protein synthesis inhibitors are used for

Answer 2

intracellular pathogens like legionella or bacteriaa that lack cell walls like mycoplasma

Question 3

mechanisms of resistance for protein synthesis inhibitors (3)

Answer 3

1. target site alteration
2. efflux
3. enzymatic inactivation

Question 4

doxycyxline bind reversibly to the ___ ribosome which inhibits protein synthesis

Answer 4

30s

Question 5

Think of doxycycline as the “________ illness” agent

Answer 5

tick borne

Question 6

doxycycline used mostly for

Answer 6

gram positive bacteria such as s. aureus and S. pneumonia but mostly for spirochetes like lyme and alt. tx for syphilis and some activity against community acquired MRSA

** Borrelia burgdoferi (agent of Lyme disease)
Treponema pallidum  (agent of syphilis - alternative therapy)

Question 7

doxycycline has a decreased reabsorption if taken with

Answer 7

positve ions that causes chelation

Question 8

doxycycline side effects (3)

Answer 8

1. yellow brown discoloration of teeth
2. esophageal ulceration
3. photosensitivity

Question 9

aminoglycosydes inhibit ___ ribosomal subunit and acts against gram___

• potentially toxic to: (2)

Answer 9

aminoglycosydes inhibit 30s ribosomal subunit and acts against gram negative bacilli

• potentially toxic to: (1) inner ears (2) kidneys

Question 10

aminoglycosides that is most used

Answer 10

gentamicin

Question 11

aminoglycosides exhibit _________ only one high dose is needed

Answer 11

concentration dependent killing

Question 12

for both gram positive and gram negative organisms, the drugs continue to suppress bacterial growth even when the serum level is below the MIC of the drug

Answer 12

post-antibiotic effect if the initial dose is high enough

Question 13

Most frequent clinical use of aminoglycosides is empiric therapy of serious gram negative infections such as sepsis – intent is to increase chances pathogens is susceptible to at least one drug in the combination

Answer 13

yep

Question 14

adverse effects to aminoglycosides

Answer 14

Nephrotoxicity
- Aminoglycosides are filtered across glomerulus with partial reabsorption in proximal tubule

Ototoxicity

• Vestibular (vertigo, disequilibrium)
• Cochlear (tinnitus, hearing loss)

Question 15

how can we minimize the toxicities of aminoglycosides

Answer 15

monitoring serum drug levels

Question 16

resistance of aminoglycosides (3)

Answer 16

1. inactivating enzymes
2. active efflux pumps
3. ribosomal mutation by methylation

Question 17

what type of medications?

Erythromycin
E-mycin
Clarithromycin
Biaxin
Azithromycin
Zithromax
Z-Pack

Answer 17

types of macrolides

Question 18

macrolides binds to the ___ ribosome and inhibits _____

Answer 18

macrolides binds to the 50s ribosome and inhibits translocation

Question 19

what is one of the things we need to pay attention to erythromycin?

Answer 19

potent inhibitor of hepatic cytochrome p4503A enzymes leading to drug-drug interactions

Question 20

erythromycin will result in which ekg change?

Answer 20

QT prolongation- increasing the risk of arrhythmia

Question 21

macrolides are most often used to treat

Answer 21

upper resp. infection or community acquired pneumonia

Question 22

Newer macrolides such as Azithro and clarithro are more acid stable than erythromycin which provides improved

Answer 22

oral absorption and tolerance, longer serum half lives

Question 23

fidaxomicin is used to treat ______ and inhibits protein synthesis by inhibiting RNA synthesis by interacting with _______

Answer 23

fidaxomicin is used to treat C.difficile and inhibits protein synthesis by inhibiting RNA synthesis by interacting with RNA polymerase

Question 24

clindamycin binds to ____ ribosomal subunit and it is known to inhibit _______ in toxin producing strains of staph and strep

Answer 24

clindamycin binds to 50s ribosomal subunit and it is known to inhibit toxin productionin toxin producing strains of staph and strep

Question 25

disdvantage of clindamycin

Answer 25

can cause C.difficile

Question 26

clindamycin is active against

Answer 26

gram positve (strep), anaeorbic infection

Question 27

linezolid binds to ___ ribosome and prevents the formation of _____

Answer 27

linezolid binds to 50s ribosome and prevents the formation of intiation complex

Question 28

linezolid niche

Answer 28

active against resistant gram positive infections

Question 29

adverse effects on linezolid

Answer 29

1. bone marrow suppression

2. serotonin syndrome