Inhibitors of protein synthesis 2 Flashcards
How is erythromycin produced?
by the soil bacterium saccropolyspora eythraea
What does the alternating oxygen pattern of erythromycin show what it is based on?
it is a polyketide based on propionate (not acetate like tetracycline)
What are the indications for macrolides?
- Gram positive infections
- TB, Legionnaires syndrome (pneumonia)
- first line treatment for penicillin allergic patients
What are the problems in use for macrolides?
- metabolised by cytochrome P450 so drug drug interactions
- erythromycin can’t be taken with food
- bitter and foul tasting and taste can’t be masked
What is the mode of action of erythromycin?
blocks the bacterial ribosomal exit tunnel
Why is erythromycin not liked in children and what is given instead?
tastes foul
erythromycin ethyl succinate given instead which is a prodrug hydrolysed to erythromycin in the body (but also hydrolysed in the bottle so kept in drudge to prevent this)
What is the first generation macrolide and what are the second gens?
first: erythromycin
second: azithromycin, clarithromycin
Why are second generations better?
more acid stable (erythromycin usually EC due to not being stable in acid)
What is the only ketolide in use? (but not in BNF) why are they better than other macrolides?
telithromycin - not susceptible to macrolide resistance
In what 2 ways have macrolides developed resistance?
- ribosomal protein modified on exit tunnel
- efflux pumps, pumping the macrolides out
What produces chloramphenicol and how is it produced?
fungal product but produced by total synthesis
Chloramphenicol has 2 chiral centres but how many of the stereoisomers are active?
only one
What is the difference by how clindamycin and lincomycin are produced?
clinamycin: semi synthetic
lincomycin: natural
Which macrolide is used to treat toxic shock syndrome? in a combination with …
clindamycin, in combination with vancomycin
What is fusidic acid produced from?
fungal product, terpenoid
