Macrolide & Ketolide Antibiotics – Comparison Chart and MCQ for GPAT, NEETPG, BPharm, BPT, MBBS, BDS and Nursing Exams
Macrolide & Ketolide Antibiotics – Comparison Chart
| Feature | Azithromycin | Roxithromycin | Clarithromycin |
|---|---|---|---|
| Class | Macrolide | Macrolide | Macrolide |
| Generation | Second-gen | Semi-synthetic | Semi-synthetic |
| Spectrum | Broad (gram +ve, some -ve) | Similar to erythromycin | Similar to erythromycin, better for H. pylori |
| Half-life (t½) | ~68 hours | ~12 hours | ~3–7 hours |
| Dosing Frequency | Once daily | Twice daily | Twice daily |
| Acid Stability | High | Better than erythromycin | High |
| Food Interaction | Take 1 hr before / 2 hr after | Less affected by food | Can be taken with food |
| Uses | URTI, LRTI, Chlamydia, MAC | Pharyngitis, bronchitis | URTI, H. pylori in ulcers |
| Metabolism | Hepatic | Hepatic | Hepatic (CYP3A4 inhibitor) |
| Excretion | Bile | Bile | Urine & bile |
| Adverse Effects | GI upset, QT prolongation | GI disturbance, metallic taste | GI upset, QT prolongation |
| Ketolide example | – | – | Telithromycin (Ketolide) |
Key Points for GPAT / NEET PG:
-
Azithromycin: Preferred for Chlamydia, Mycobacterium avium complex (MAC), once-daily dosing.
-
Clarithromycin: Used with amoxicillin + PPI for H. pylori eradication.
-
Roxithromycin: Longer t½ than erythromycin; useful for respiratory infections.
-
Ketolide (Telithromycin): Reserved for resistant respiratory pathogens; contraindicated in myasthenia gravis due to risk of respiratory failure.
MCQs on Macrolides & Ketolides
1. Which macrolide is most commonly used for single-dose treatment of Chlamydia trachomatis?
A. Roxithromycin
B. Clarithromycin
C. Azithromycin
D. Erythromycin
Answer: C. Azithromycin
2. Which macrolide is best used in triple therapy for H. pylori eradication?
A. Azithromycin
B. Clarithromycin
C. Roxithromycin
D. Telithromycin
Answer: B. Clarithromycin
3. Which of the following has the longest half-life?
A. Clarithromycin
B. Erythromycin
C. Azithromycin
D. Roxithromycin
Answer: C. Azithromycin
4. Which of the following is a ketolide antibiotic?
A. Telithromycin
B. Clarithromycin
C. Azithromycin
D. Spiramycin
Answer: A. Telithromycin
5. A patient with myasthenia gravis should avoid which antibiotic due to risk of fatal respiratory failure?
A. Azithromycin
B. Telithromycin
C. Clarithromycin
D. Roxithromycin
Answer: B. Telithromycin