Azithromycin use in paediatrics: a practical overview

Question 1

What are the pharmacokinetic properties of azithromycin?

Answer 1

1. Stable in acidic pH
2. Bioavailability >30%
3. Relatively long half life up to 96h
4. Significant intracellular diffusion
5. Transported in cells not blood

Question 2

What is the mechanism of action for azithromycin?

Answer 2

Inhibits bacterial protein synthesis by binding to the 50S subunit of ribosomes and blocking protein translocation

Question 3

What is the spectrum of activity for azithromycin?

Answer 3

Lower in vitro activity against gram positive bacteria i.e. streptococcus pneumoniae but better in vitro activity against gram negative bacteria i.e. H. flu and Moraxella catarrhalis

Question 4

When should azithromycin be used to treat acute pharyngitis, AOM, or CAP in otherwise healthy children?

Answer 4

1. Second line treatment in cases of life-threatening beta-lactam allergy to treat acute pharyngitis caused by macrolide sensitive GAS
2. Pneumonia caused by atypical bacteria

Question 5

What is the concern with increased prescription of azithromycin?

Answer 5

Rising rates of resistance especially pneumococci

Question 6

Why is azithromycin prescribed commonly?

Answer 6

1. Once daily dosing
2. Short treatment duration (3-5 days)
3. Favourable side effect profile
4. Easy administration in oral prescription