Antibiotics: Macrolides (clarithromycin, erythromycin, azithromycin) Flashcards
Indications of macrolides?
Treats:
- respiratory, skin and soft tissue infections (if penicillin contraindicated)
- severe pneumonia (+ penicillin to treat ATYPICAL PNEUMONIA organisms e.g. Legionella/Mycoplasma pneumonia)
- H. pylori (triple therapy)
Examples of macrolides?
clarithromycin
erythromycin
azithromycin
Spectrum of activity of macrolides?
Broad spectrum
Works against Gram-positive and Gram-negative organisms.
MOA of macrolides?
Inhibits bacterial protein synthesis -BACTERIOSTATIC
Binds to 50S subunit of the bacterial ribosome and blocks translocation.
→ so polypeptide can’t elongate.
Adverse effects of macrolides?
Irritant causes (when taken orally):
- Nausea
- Vomiting
- Abdominal pain
- Diarrhoea
- thrombophlebitis (if taken IV)
Antibiotic-associated collitis (C.diff)
Allergy
Liver abnormalities (cholestatic jaundice)
Prolongation of QT interval
Ototoxicity (at high doses)
Warnings of macrolides?
Contraindicated in hx of macrolide hypersensitivity
Caution in:
- severe hepatic impairment
Reduce dose in severe renal impairment.
Interactions of macrolides?
Erythromycin and clarithromycin INHIBIT cytochrome P450 enzymes.
Monitoring of macrolides?
Check infection resolves by:
- symptoms/signs improved (e.g. pyrexia, lung crackles, dysuria)
- blood markers e.g. falling CRP and WCC
Pt education of macrolides?
Aims to get rid of infection and improve symptoms.
Check for macrolide allergy.
Seek medical advice if they develop a rash or unexpected symptoms.
If allergy develops during treatment, give pt written and verbal advice NOT to take this abx class in future and make sure that the type of reaction (including its nature) is clearly documented in pt’s medical records.
Which macrolides are synthetic? What do they have increased activity against?
Clarithromycin
Azithromycin
Increased activity against Gram-negative (haemophilus influenzae).
