Zithromax (azithromycin) is a macrolide antibiotic renowned for its potent activity against a wide range of bacterial pathogens. It is widely prescribed for respiratory, skin, and sexually transmitted infections due to its favorable pharmacokinetic profile and convenient dosing regimen. Its extended tissue half-life allows for shorter treatment courses, enhancing patient compliance and therapeutic outcomes.

Features

• Active ingredient: Azithromycin dihydrate
• Available forms: Tablets (250 mg, 500 mg), oral suspension (100 mg/5 mL, 200 mg/5 mL), powder for injection
• Mechanism: Inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit
• Spectrum: Effective against Gram-positive, Gram-negative, anaerobic, and atypical bacteria
• Dosing flexibility: Once-daily administration, with options for 3-day or 5-day courses

Benefits

• Rapid onset of action with high tissue concentrations achieved quickly
• Short treatment duration improves adherence and reduces risk of resistance development
• Broad coverage includes common community-acquired pathogens and intracellular organisms
• Well-tolerated profile with generally mild side effects
• Convenient dosing regardless of meals (though taking with food may reduce GI discomfort)
• Proven efficacy in both adult and pediatric populations (where approved)

Common use

Zithromax is indicated for the treatment of mild to moderate infections caused by susceptible strains of designated microorganisms. Common uses include community-acquired pneumonia, acute bacterial exacerbations of chronic obstructive pulmonary disease, acute bacterial sinusitis, pharyngitis/tonsillitis, uncomplicated skin and skin structure infections, urethritis and cervicitis, and genital ulcer disease. It is also used in pediatric patients for acute otitis media and community-acquired pneumonia.

Dosage and direction

Dosage varies by indication, severity of infection, and patient factors. Typical adult doses range from 500 mg as a single dose on day 1 followed by 250 mg once daily on days 2 through 5, to 500 mg once daily for 3 days. For sexually transmitted diseases, a single 1 gram dose is often prescribed. Pediatric dosing is weight-based. Tablets should be swallowed whole with water; suspension should be shaken well before use. May be taken with or without food, though administration with food may minimize gastrointestinal upset.

Precautions

Use with caution in patients with hepatic impairment. Periodic liver function tests are advisable during prolonged therapy. May exacerbate weakness in patients with myasthenia gravis. Use in pregnancy only if clearly needed (Category B). Azithromycin is excreted in human milk; caution should be exercised when administering to nursing women. Prolonged use may result in superinfection. Prescribers should consider the risk of QT prolongation, particularly in patients with known risk factors.

Contraindications

Known hypersensitivity to azithromycin, erythromycin, or any other macrolide antibiotics. Contraindicated in patients with a history of cholestatic jaundice/hepatic dysfunction associated with prior azithromycin use. Should not be used concomitantly with drugs that prolong QT interval and are metabolized by CYP3A4, such as pimozide.

Possible side effect

Common side effects include diarrhea/loose stools (4-5%), nausea (3%), abdominal pain (2-3%), and vomiting. Less frequently reported effects include headache, dizziness, and changes in taste. Serious but rare side effects may include hepatotoxicity, QT prolongation, torsades de pointes, Clostridioides difficile-associated diarrhea, and allergic reactions. Discontinue use if severe skin reactions or hepatitis occur.

Drug interaction

May potentiate effects of warfarin (monitor INR). Concurrent use with nelfinavir increases azithromycin levels. May increase concentrations of digoxin, theophylline, and cyclosporine. Antacids containing aluminum or magnesium may reduce peak serum levels (administer azithromycin至少1 hour before or 2 hours after these agents). Concomitant use with other QT-prolonging agents should be avoided.

Missed dose

Take the missed dose as soon as remembered. If it is almost time for the next dose, skip the missed dose and continue with the regular dosing schedule. Do not double doses to make up for a missed dose.

Overdose

Symptoms may include severe nausea, vomiting, diarrhea, and temporary hearing loss. Gastric lavage and general supportive measures are recommended. There is no specific antidote for azithromycin overdose.

Storage

Store at room temperature (15-30°C/59-86°F). Keep container tightly closed. Protect from light and moisture. Oral suspension remains stable for 10 days after reconstitution when stored at room temperature or refrigerated (do not freeze). Keep out of reach of children.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Always consult a healthcare professional for diagnosis and treatment recommendations. Do not self-medicate or alter prescribed dosages without medical supervision.

Reviews

Clinical studies demonstrate Zithromax’s efficacy with cure rates of 85-95% for respiratory infections and 92-97% for skin/soft tissue infections. Physicians frequently note the convenience of short-course therapy and generally favorable tolerability profile. Some reports mention gastrointestinal side effects as the most common reason for discontinuation. Overall satisfaction remains high among both prescribers and patients when used appropriately for susceptible infections.