Walters - Macrolides

Question 1

what is a macrolide composed of. what are they effective against?

Answer 1

lactone ring + 1 or more deoxy sugars. All are effective vs MSSA, morale catarrhalis, and H. inflenza

Question 2

Macrolide work against gram + and some gram - organisms and they are mostly _____.

Answer 2

static

Question 3

what are the mechanisms of macrolides

Answer 3

1. inhibit translocation from A to P site (in reference to ribosomes)
2. release peptidyl tRNA from ribosomes.
3. block formation of initiation complex.

Question 4

_____ is the first macrolide that came out and was the first drug to be effective vs _____ disease.

Answer 4

Eryhtromycin; Legionnaire’s

Question 5

Erythromycin + ______ is to treat OM

Answer 5

sulfisoxazole

Question 6

erythromycin inhibits _____ the isoenzyme that is involved in drug metabolism and metabolizes erythromycin; its metabolites complex with cytochrome heme ____

Answer 6

CYP3A4; Fe+

Question 7

Erythromycin prolongs cardiac repolarization which increases Torsades de Pointes which effect the _____ channel

Answer 7

K+

Question 8

Erythromycin doubles risk of sudden death. You are 5 x more at risk if your taking ____ or _____

Answer 8

diltiazem; verapamil

Question 9

Erthythromicin has a _____ ability by stimulating peristalsis post op; speeds gastric emptying with gastroparesis

Answer 9

prokinetic

Question 10

_______ is a macrolide that concentrates intracellularly.

Answer 10

Azithromycin

Question 11

What are the uses of azithromycin

Answer 11

1. community acquired pneomonia
2. Legionnaires disease
3. Mycobacterium avium complex

Question 12

Azithromycin does not inhibit ____ unlike erythromycin and is excreted unchanged in the ile

Answer 12

P450

Question 13

What is the FDA warning for azithromycin

Answer 13

1. it can cause changes in electrical activity of the heart that might lead to potentially fatal irregular rhythms. There is a greater risk in patients with known Q-T prolongation or low K+ or Mg+ levels.

Question 14

_____ is a macrolide that is used for community acquired pneumonia and mycobacterium avum complex. It is immunomodulatory that inhibit mRNA transcription for pro inflammatory cytokines.

Answer 14

Clarithromycin

Question 15

Clarithromycin can ____ blood sugar.

Answer 15

lower

Question 16

Clarithromycin inhibits ____. Have caution with colchicine; used in treatment of gout. Possibly fatal. Try azithromycin which doesn’t inhibit P450

Answer 16

CYP3A; colchicine

Question 17

Macrolides as a class might increase ____ toxicity

Answer 17

digoxin; used in treating atrial arrhythmia and heart failure

Question 18

Telithromycin is a _____ and increases gram ____ activity . It has the same mechanism as macrolide but binds 2 sep. domains on ribosome and decreases risk of resistance. They have a broader activity

Answer 18

ketolide; +

Question 19

What is telithromycin used for

Answer 19

community acquired respiratory infections. concentrates in pulmonary tissues and WBCs and is active against beta lactam and macrolide resistant microbes

Question 20

Ketolide inhibits ____ which prolongs QT interval

Answer 20

CYP3A4

Question 21

what is the black box warning for telithromycin

Answer 21

contraindicated in mysthenia gravis. Fatal or life thretening respiratory failure.

Question 22

______ is given parenterally only for aerobic/anerobin G= and G- microbes. It is used for serious and fatal blood dycrasias and limit to serious resistant infections! only use when nothing else works!

Answer 22

chloramphenicol

Question 23

what is the mechanism for chloramphenicol

Answer 23

inhibits binding of aminoacyl tRNA to acceptor site. (same as tetracyclines)

Question 24

what is the problem for chloramphenicol

Answer 24

inhibits human mitochondrial peptidyl transferase

Question 25

What cells are most sensitive to chloramphenicol

Answer 25

1. erythropoietic cells –> leukopenia, thrombocytopenia, fatal aplastic anemia

Question 26

_____ in low levels predisposes to hemolytic anemia

Answer 26

G6PD

Question 27

Chloramphenicol causes gray baby syndrome. What is it caused by?

Answer 27

1. insufficient glucouronyl transferase; can’t conjugate

2. underdeveloped renal function; can’t eliminate

Question 28

Inc drug levels of chloramphenicol interfere with mitochondrial ribosomes and cause:

Answer 28

1. depressed respiration
2. cardiovascular collapse
3. cyanosis (gray baby)