15. Macrolides. Ketolides

Question 1

Macrolides

Answer 1

Erythromycin
Clarithromycin
Azithromycin

Question 2

Ketolide

Answer 2

Telithromycin

Question 3

Erythromycin
Clarithromycin
Azithromycin

Answer 3

Macrolides
Protein synthesis inhibitor S50 subunit - Irreversible inhibition (inhibits translocation step)
Bacteriostatic (cidal in high doses)

Resistance: Inability to take up the antibiotic, efflux pump, decreased affinity of 50S subunit.

Question 4

Telithromycin

Answer 4

Bactericidal

Spectrum: as macrolides + macrolide resistant bacteria
Effective against macrolide resistant bacteria

Kinetics: good oral absorption
Distribution: well | accumulate

Adverse effect: Hepatotoxicity, QT prolongation | visual disturbances, CYP3A4 inhibitor

Question 5

Erythromycin

Answer 5

Spectrum: G+ive cocci
Clinical use: penicillin allergies

Administration: oral (coated/esterified tablets), food interferes with absorption | IV
Distribution: Well except CSF | accumulates in macrophages
Metabolism: Hepatic
Elimination: Bille

Adverse effect: GI (motilin receptor stimulation) | Cholestatic jaundice | Ototoxicity

Question 6

Clarithromycin

Answer 6

Spectrum: more potent against G+ive | G-ive | H. influenzae, H. Pylori | Chlamydia | M.avium

Kinetics: good bioavailability | renal excretion
Administration: Oral and IV, food increases absorption.
Distribution: Well
Elimination: Kidney

Adverse effect: Less GI, few interactions

Question 7

Azithromycin

Answer 7

Spectrum: more potent against G-ive | G+ive Cocci, G-ive Cocci, borrelia burgdorferi | M.avium

Clinical use: Uretritis (chlamydia)

Administration: Oral and IV
Kinetics: longest half life and largest Vd
Distribution: Well | concentrated in neutrophils, macrophages and fibroblasts |
Elimination: Liver

Adverse effect: Less GI, no interactions