Macrolides Flashcards
Name 3 Macrolides:
Azithromycin
Erythromycin
Clarithromycin
Are macrolides Bactericidal or bacteriostatic?
Bacteriostatic
Prototype drug in Macrolide group
Erythromycin
Azithromycin is derived from
Erythromycin
Due to drug interactions and side effects of Erythromycin and clarithromycin
Azithromycin is preferred and is the majority of macrolide use
Macrolides exhibit
Immunomodulating properties (useful in infectious diseases and cystic fibrosis)
Macrolide MOA
Bind to 50s ribosomal subunit to inhibit protein synthesis
Azithromycin is used for:
Chancroid
Chlamydia in pregnant patients
Gonorrhea if patient has cephalosporin allergy
Chronic bronchitis, sinusitis, CAP, Pharyngitis, and tonsillitis
Uncomplicated skin soft tissue infections
Chlamydia trachomatis and gonorrhea
Travelers diarrhea
Erythromycin Indications
CAP, bronchitis, pertussis
Impetigo cellulitis
Neonatal conjunctivitis caused by (N. gonorrhoeae or chlamydia trachomatis)
Chlamydia
Prophylaxis for rheumatic fever in those with penicillin allergies
Bacterial endocarditis for dental or surgical procedures
Macrolides absorption
Well-absorbed from the duodenum with oral administration
Minimal absorption from topical or ophthalmic use
Macrolide Distribution
Readily to body tissues
Enters pleural fluid, ascitic fluid, middle ear exudates, and sputum.
Meninges if they are inflamed
Enter CSF
Macrolide Metabolism
partially by the liver
Macrolide excretion
mainly unchanged in the bile, also unchanged in the urine
Both Erythromycin and Clarithromycin have a higher number of
drug interaction due to? What medication should be stopped if taking either abx?
being strong inhibitors of the CYP enzymes (CYP3A4)
HMG-CoA Reductase Inhibitors (Statins) should be stopped while on
either due to risk of severe myopathy or rhabdomyolysis
Erythromycin is heavily metabolized by
CYP3A4 which explains its many drug interactions
Erythromycin contraindicated in patients with?
Preexisting liver disease
Azithromycin should be used with caution in these patients:
Patients with hepatic dysfunction
What EKG change has been observed?
QT interval
Macrolide ADRs
Dose-related GI symptoms, including nausea, vomiting, abdominal pain, cramping, and diarrhea.
Azithromycin and erythromycin ADRs
Associated with liver abnormalities, including hepatitis, cholestatic jaundice, and hepatic failure.
What’s the major reason selecting azithromycin over other macrolides?
Enhanced compliance due to convenient once a day dosing for 3 to 5 days, missing one day could cause unsuccessful treatment.
Macrolide Resistance
(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.
