Macrolides

Question 1

What are the drugs under the Macrolide class?

Answer 1

Erythromycin
Clarithromycin
Azithromycin
Telithromycin

Question 2

What is the MOA of macrolides?

Answer 2

They bind to a site on the 50s ribosome unit of the bacteria and inhibit steps of protein synthesis, which is crucial for bacterial growth and replication. Typically bacteriostatic but can be bactericidal at higher doses.

Question 3

What is the spectrum of activity for Macrolides?

Answer 3

Alternative for patients allergic to Penicillin
Broad spectrum of activity that includes Gram (+) and Gram (-) bacteria

Question 4

What are side effects of Macrolides?

Answer 4

GI Upset: High doses of Erythromycin especially can cause smooth muscle contractions, causing gastric contents to move into the duodenum. This can be helpful in treating gastroparesis and post-operative ileus.

Ototoxicity

Hepatotoxicity

Prolonged QT Interval

Question 5

What is their interaction with the CYP450 family?

Answer 5

Erythromycin and Clarithromycin both inhibit CYP450 which inhibits the metabolism of many drugs.

Question 6

What is Fidoxamicin?

Answer 6

Fidoxamicin is a drug similar to macrolides but has a unique MOA. It acts on the unit or the RNA polymerase, disrupting bacterial transcription, so it is bactericidal.

Question 7

What is the main use for giving Fidoxamicin?

Answer 7

Use primarily for C. diff

Question 8

What is the spectrum of activity with Fidoxamicin?

Answer 8

Very narrow spectrum of activity, targeting Gram (+) aerobes and anaerobes.