Azithromycin: Uses, Dosage, Side Effects, and More
1. Drug Name
Generic Name: Azithromycin
Brand Name(s):
- Pakistan: Azomax, Zithro
- India: Azithral, Zithrox
- United States: Zithromax, Z-Pak
- United Kingdom: Zithromax
2. Pharmacological Class
Class: Antibiotic
Subclass: Macrolide
3. Mechanism of Action
Azithromycin works by binding to the 50S ribosomal subunit of the bacterial ribosome, inhibiting protein synthesis and thereby preventing bacterial growth.
4. Indications
Primary Indications:
- Treatment of various bacterial infections such as respiratory infections, skin infections, ear infections, and sexually transmitted diseases.
Off-label Uses:
- Prevention of mycobacterium avium complex (MAC) in patients with HIV.
5. Dosage and Administration
Standard Dosage:
- Adults (mild to moderate infections): 500 mg on the first day, followed by 250 mg once daily for the next 4 days.
Route of Administration: Oral (tablets, suspension) and intravenous.
Special Populations:
- Pediatric: Dosage is weight-based, typically 10 mg/kg on the first day, followed by 5 mg/kg once daily for the next 4 days.
- Geriatric: No specific dose adjustment required, but caution advised in renal impairment.
6. Pharmacokinetics
Absorption: Azithromycin is well absorbed from the gastrointestinal tract.
Distribution: It is widely distributed in body tissues and fluids.
Metabolism: Azithromycin is minimally metabolized in the liver.
Excretion: It is primarily excreted unchanged in the bile and urine.
Half-life: Approximately 68 hours.
7. Contraindications
Azithromycin is contraindicated in patients with a history of allergic reactions to azithromycin, erythromycin, or any macrolide or ketolide antibiotic.
8. Warnings and Precautions
Use with caution in patients with liver disease, myasthenia gravis, or a history of QT prolongation. Prolonged use may result in fungal or bacterial superinfection, including C. difficile-associated diarrhea.
9. Side Effects
Common Side Effects: Nausea, vomiting, diarrhea, abdominal pain, and headache.
Serious Side Effects: Anaphylaxis, liver damage, QT prolongation, and Clostridium difficile-associated diarrhea.
10. Drug Interactions
Major Interactions: Warfarin (increased risk of bleeding), antiarrhythmic drugs (increased risk of QT prolongation).
Moderate Interactions: Digoxin (increased digoxin levels), cyclosporine (increased cyclosporine levels).
Minor Interactions: Antacids containing aluminum or magnesium (reduced absorption of azithromycin).
11. Pregnancy and Lactation
Pregnancy Category: Category B - No evidence of risk in humans.
Breastfeeding Considerations: Azithromycin is excreted in breast milk in small amounts. Use with caution.
12. Patient Counseling Information
Key Points for Patients:
- Take azithromycin exactly as prescribed, even if you feel better before completing the course.
- Report any signs of allergic reaction, such as rash, itching, or swelling, to your doctor immediately.
Administration Tips:
- Take with or without food. If stomach upset occurs, take with food.
- Shake the suspension well before each use and measure the dose with the provided measuring device.