Treatment / Antimicrobials / Macrolides
Macrolides
Selection Strategy
- Know efficacy vs. the bug:
CLARITHROMYCIN vs. azithromycin:
- MIC50: .03 vs. .06
- MIC90: .06 vs. .25
-
Identify route of administration: no critical differences within this class
-
Acid stability is preferred à CLARITHROMYCIN is more stable than erythromycin
- Increase patient compliance:
Azithromycin and CLARITHROMYCIN vs. erythromycin:
- decreased dosing (H. pylori regimens are complicated and long)
- decreased GI effects (anorexia, nausea, vomiting, diarrhea; stimulation of gut motility)
- azithromycin has decreased drug interactions compared to the other 2 drugs (no CYP450 inactivation)
CLARITHROMYCIN is the macrolide antibiotic of choice for H. pylori treatment (azithromycin and erythromycin should not be substituted). CLARITHROMYCIN has a substantially lower MIC90, is more acid stable and has fewer side effects. |
 |
MECHANISM OF ACTION and UNIQUE TOXICITY:
- bacterioSTATIC
- protein synthesis inhibitor (binds to 50s ribosomal RNA to prevent translocation)
- GI irritation, drug interactions (CLARITHROMYCIN is both a substrate and an inhibitor of CYP3A4)