Paper II — 2014 March (2010 Scheme) — Q5

Paper II

2014 March (2010 Scheme) · 40 marks · 120 min

Question

Azithromycin

Q53 marksShort Notes★✓

Answer

Azithromycin is an azalide (macrolide-class) antibiotic.

Mechanism of action

• Binds to the 50S ribosomal subunit, inhibiting bacterial protein synthesis by blocking translocation

Special pharmacokinetic features

• Long tissue half-life, high tissue penetration, low plasma levels — allows short-course therapy (e.g., 3–5 days) and once-daily dosing
• Minimal interaction with cytochrome P450 (unlike erythromycin)

Uses

• Respiratory tract infections (community-acquired pneumonia, sinusitis)
• Sexually transmitted infections — Chlamydia trachomatis (single-dose therapy), non-gonococcal urethritis
• Typhoid fever
• Atypical pneumonia (Mycoplasma, Legionella)
• Prophylaxis of Mycobacterium avium complex in HIV patients

Adverse effects

• GI upset (less than erythromycin)
• QT prolongation
• Hepatotoxicity (rare)

Related Concepts

1. 1Macrolides and Other Antibacterials

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