MACROLIDES AND AZALIDES Flashcards
What is the prototype drug in this group?
erythromycin
What are the two drugs within the MACROLIDES AND AZALIDES group?
erythromycin and clindamycin
What is a chemically an azalide derived from erythromycin?
azithromycin (Zithromax)
What is the preferred and constitutes the vast majority of macrolide use?
azithromycin
Due to the drug interaction and side effect profiles of erythromycin and clarithromycin,
Macrolides exhibit what kind of properties that help in their effectiveness in infections and cystic fibrosis?
exhibit immunomodulating properties
What is the MOA of macrolides and azalides?
reversibly binds to the P site of the 50S ribosomal subunit of susceptible organisms and may inhibit RNA-dependent protein synthesis by stimulating the dissociation of peptidyl-tRNA from ribosomes.
What activity do macrolides and azalides have?
Atypical and intracellular organisms commonly resistant to beta-lactam antibiotics
What activity does Clarithromycin have?
greater activity than erythromycin or azithromycin against gram-positive organisms such as Streptococcus species and MSSA
Best macrolide in treating H. influenzae?
Azithromycin
How is resistance mediated for macrolides and azalides?
(1) reduced permeability of the cell membrane or active efflux,
(2) modification of the ribosomal binding site by chromosomal mutation, or
(3) production of esterase by Enterobacterales that hydrolyze macrolides.
How are macrolides and azalides absorbed?
Well-absorbed from the duodenum following oral administration
Minimal absorption occurs after topical or ophthalmic use.
How are macrolides and azalides distributed?
Distribute readily to body tissues and enter pleural fluid, ascitic fluid, middle-ear exudates, and sputum. When meninges are inflamed, macrolides enter the CSF.
How are macrolides and azalides metabolized?
Partially metabolized by the liver, and clarithromycin is converted to active metabolites
How are macrolides and azalides excreted?
Excreted mainly unchanged in bile; the drug is also excreted unchanged in urine in varying degrees
Why does erythromycin have so many drug interactions?
Erythromycin is heavily metabolized by CYP3A4, which explains many of its drug interactions.