Azithromycin

Azithromycin – Full Introduction

Azithromycin is a broad-spectrum macrolide antibiotic widely used to treat bacterial infections. It is valued for its long half-life, tissue penetration, and convenient dosing schedule.

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Drug Class

• Macrolide antibiotic

• Bacteriostatic (inhibits bacterial growth)

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Mechanism of Action

Azithromycin works by binding to the 50S subunit of bacterial ribosomes, which:

• Inhibits bacterial protein synthesis

• Prevents bacterial growth and replication

It is effective against a wide range of gram-positive, gram-negative, and atypical bacteria.

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Therapeutic Uses

• Respiratory tract infections (pneumonia, bronchitis, sinusitis)

• Skin and soft tissue infections

• Sexually transmitted infections (chlamydia, gonorrhea)

• Otitis media (middle ear infection)

• Pertussis (whooping cough)

• Mycobacterial infections in combination therapy

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Benefits

• Long half-life → once-daily dosing

• Good tissue penetration

• Generally well tolerated

• Effective against atypical organisms (Mycoplasma, Chlamydia)

• Shorter treatment courses (3–5 days in many infections)

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Common Side Effects

• Nausea and vomiting

• Diarrhea

• Abdominal pain

• Mild headache

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Serious but Rare Side Effects

• Allergic reactions (rash, anaphylaxis)

• Hepatotoxicity (rare)

• QT interval prolongation → risk of arrhythmias

• Severe diarrhea due to Clostridium difficile infection (rare)

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Contraindications & Precautions

• Known hypersensitivity to azithromycin, erythromycin, or other macrolides

• History of QT prolongation or cardiac arrhythmias

• Severe hepatic impairment

• Use caution in patients taking other QT-prolonging drugs

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Dosage & Administration

• Adults: 500 mg on day 1, then 250 mg once daily for 4 more days (common regimen)

• Children: Dose based on body weight (10 mg/kg on day 1, then 5 mg/kg once daily for 4 days)

• Available forms: tablet, suspension/syrup, IV

• Can be taken with or without food

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Conclusion

Azithromycin is a safe and effective antibiotic for a wide range of infections, offering the advantages of once-daily dosing and short treatment courses. Monitoring is advised in patients with cardiac or hepatic risks.