C/15. Macrolides. Ketolides

Question 1

Macroldes. Ketolides

MOA

Answer 1

Binds to the 50S ribosomal subunit
Inhibit translocation of peptidyl tRNA from acceptor to donor site
Bacteriostatic effect

Question 2

Roxithromycin

Answer 2

derived from erythromycin

Broad spectrum;
Gram +,- atypcal
Chlamydia, mycoplasma, legionella, campylobacter
Bordetella pertusis
Community acquired pneumonia
No activity against MRSA and PRSP

Oral
Biliary elimination
Inhibitor of CYP450 enzymes

Resistance mechanism
Methylation of ribosomal binding site
Efflux pump
Drug metabolising esterase enzymes

GI distress
Ototoxicity
Skin rash
Eosinophillia
QT prolongation
Acute cholestatic hepatitis

Question 3

Azithromycin

Answer 3

Similar to erythromycin
More selective to Neisseria, H. Influenza, M. Catarrhalis
Urogenital infections caused by chlamydia

Absoprtion impeded by food
Reaches high intracellular concentration
Renal elimination

Resistance mechanism
Methylation of ribosomal binding site
Efflux pump
Drug metabolising esterase enzymes

GI distress
Ototoxicity
Skin rash
Eosinophillia
QT prolongation
Acute cholestatic hepatitis

Question 4

Clarithromycin

Answer 4

Similar to erythromycin
Prophylaxis against M. Avium
H. Pylori eradication regimen

Hepatic metabolism
Renal elimination
Inhibitor of CYP450 enzymes

Resistance mechanism
Methylation of ribosomal binding site
Efflux pump
Drug metabolising esterase enzymes

GI distress
Ototoxicity
Skin rash
Eosinophillia
QT prolongation
Acute cholestatic hepatitis

Question 5

Ketolide

Answer 5

Structurally related to macrolides

MOA, resistance, and specturm similar to erythromycin

Question 6

Telithromycin

Answer 6

Macrolide-resistant strains (S. Pneumoniae)

Oral
Eliminated in bile and urine
Inhibitor of CYP450 enzymes

Hepatotoxicity
QT prolongation