RN Nursing · Medications Affecting the Immune System
Macrolides: Nursing Pharmacology Study Guide
A concise NCLEX-style review of macrolide antibiotics (azithromycin, clarithromycin, erythromycin), covering mechanism, indications, side effects, and nursing safety priorities.
On this page
Macrolides are a key antibiotic class on the NCLEX, frequently used for respiratory and atypical infections. This guide reviews the three main macrolides, their mechanism of action, indications, side effects, and the nursing priorities most often tested on exams.
Drug Identification
| Drug | Key Use | Key Exam Clue |
|---|---|---|
| Azithromycin | Respiratory infections | Most commonly prescribed |
| Clarithromycin | H. pylori treatment | GI infections |
| Erythromycin | Alternative to penicillin | Penicillin allergy option |
Mnemonic — "ACE drugs":
- A – Azithromycin
- C – Clarithromycin
- E – Erythromycin
Mechanism of Action
- Inhibit bacterial protein synthesis
- Bind to the 50S ribosomal subunit
- Bacteriostatic
Exam tip: Macrolides are protein synthesis inhibitors.
Spectrum
- Cover Gram-positive bacteria and atypical pathogens
- Important atypicals: Mycoplasma, Chlamydia, Legionella
- Azithromycin is commonly used for atypical pneumonia
Indications
- Community-acquired pneumonia
- Bronchitis
- Chlamydia infection
- Pertussis
- H. pylori (clarithromycin)
Azithromycin is often chosen for penicillin-allergic patients.
Side Effects
- Common: nausea, diarrhea, abdominal pain
- Serious: QT prolongation, arrhythmias, hepatotoxicity
The most tested adverse effect is QT prolongation.
Labs to Monitor
- Liver enzymes (AST, ALT)
- ECG in high-risk patients
- Electrolytes — low potassium increases QT risk
Watch for signs of liver injury such as jaundice or dark urine.
Contraindications
- Known macrolide allergy
- History of QT prolongation
- Severe liver disease
Use cautiously with other drugs that prolong the QT interval.
Pregnancy Safety
- Azithromycin and erythromycin are generally considered safe in pregnancy.
- Commonly used to treat infections in pregnant patients.
- Always assess the patient's complete medication history.
Nursing Safety Rules
- Monitor ECG in patients with cardiac risk.
- Monitor liver function during therapy.
- Encourage patients to complete the full antibiotic course.
- Assess for drug–drug interactions.
Common NCLEX Traps
- Ignoring QT prolongation risk
- Missing signs of liver injury
- Combining with other QT-prolonging drugs
- Stopping antibiotics early
Key Takeaways
- Macrolides inhibit bacterial protein synthesis at the 50S ribosome and are bacteriostatic.
- Used primarily for respiratory infections and atypical pneumonia (Mycoplasma, Chlamydia, Legionella).
- Azithromycin is the most frequently prescribed macrolide and a go-to for penicillin-allergic patients.
- The most serious adverse effect is QT prolongation — monitor ECG and electrolytes.
- Monitor liver enzymes (AST/ALT) and watch for jaundice or dark urine.
- Azithromycin and erythromycin are generally considered safe in pregnancy.
Test yourself on Macrolide, Tetracycline, and Aminoglycoside Antibacterials
292 practice questions, each with a full teaching rationale.
Practise free