Walters - Macrolides Flashcards
what is a macrolide composed of. what are they effective against?
lactone ring + 1 or more deoxy sugars. All are effective vs MSSA, morale catarrhalis, and H. inflenza
Macrolide work against gram + and some gram - organisms and they are mostly _____.
static
what are the mechanisms of macrolides
- inhibit translocation from A to P site (in reference to ribosomes)
- release peptidyl tRNA from ribosomes.
- block formation of initiation complex.
_____ is the first macrolide that came out and was the first drug to be effective vs _____ disease.
Eryhtromycin; Legionnaire’s
Erythromycin + ______ is to treat OM
sulfisoxazole
erythromycin inhibits _____ the isoenzyme that is involved in drug metabolism and metabolizes erythromycin; its metabolites complex with cytochrome heme ____
CYP3A4; Fe+
Erythromycin prolongs cardiac repolarization which increases Torsades de Pointes which effect the _____ channel
K+
Erythromycin doubles risk of sudden death. You are 5 x more at risk if your taking ____ or _____
diltiazem; verapamil
Erthythromicin has a _____ ability by stimulating peristalsis post op; speeds gastric emptying with gastroparesis
prokinetic
_______ is a macrolide that concentrates intracellularly.
Azithromycin
What are the uses of azithromycin
- community acquired pneomonia
- Legionnaires disease
- Mycobacterium avium complex
Azithromycin does not inhibit ____ unlike erythromycin and is excreted unchanged in the ile
P450
What is the FDA warning for azithromycin
- 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.
_____ 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.
Clarithromycin
Clarithromycin can ____ blood sugar.
lower
Clarithromycin inhibits ____. Have caution with colchicine; used in treatment of gout. Possibly fatal. Try azithromycin which doesn’t inhibit P450
CYP3A; colchicine
Macrolides as a class might increase ____ toxicity
digoxin; used in treating atrial arrhythmia and heart failure
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
ketolide; +
What is telithromycin used for
community acquired respiratory infections. concentrates in pulmonary tissues and WBCs and is active against beta lactam and macrolide resistant microbes
Ketolide inhibits ____ which prolongs QT interval
CYP3A4
what is the black box warning for telithromycin
contraindicated in mysthenia gravis. Fatal or life thretening respiratory failure.
______ 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!
chloramphenicol
what is the mechanism for chloramphenicol
inhibits binding of aminoacyl tRNA to acceptor site. (same as tetracyclines)
what is the problem for chloramphenicol
inhibits human mitochondrial peptidyl transferase
What cells are most sensitive to chloramphenicol
- erythropoietic cells –> leukopenia, thrombocytopenia, fatal aplastic anemia
_____ in low levels predisposes to hemolytic anemia
G6PD
Chloramphenicol causes gray baby syndrome. What is it caused by?
- insufficient glucouronyl transferase; can’t conjugate
2. underdeveloped renal function; can’t eliminate
Inc drug levels of chloramphenicol interfere with mitochondrial ribosomes and cause:
- depressed respiration
- cardiovascular collapse
- cyanosis (gray baby)
