Azithromycin is an antibiotic useful for the treatment of a number of bacterial infections. This includes middle ear infections, strep throat, pneumonia, traveler’s diarrhea, and certain other intestinal infections. It may also be used for a number of sexually transmitted infections including chlamydia and gonorrhea infections.
Class of Drug
Mechanism of Action
Inhibits RNA-dependent protein synthesis at the level of the 50S ribosome.
Susceptible organisms in vivo: Like erythromicin but less active against gram-positive bacteria and more active against gramnegative bacteria. Better against Hemophilus influenzae and Moraxella catarrhalis. Also useful against Mycobacterium avium-intrace llulare and Helicobacter pylori.
Indications / Dosage / Route
Routes of Administration: Oral and IV.
Condition: Community-acquired pneumonia
Dose: Adults IV 500 mg as single daily dose, at least 2 days. Follow by oral dosing 500 mg/d, 7-10 days.
Condition: Acute pelvic inflammatory disease
Dose: Adults IV 500 mg as single daily dose, 1 or 2 days. Follow by oral dosing 250 mg/d 7 days.
Condition: Mild to moderate acute exacerbation of COPD, community-acquired pneumonia (mild to moderate), pharyngitis/tonsillitis (second- line therapy), uncomplicated skin and skin structure infections
Dose: Adults PO 500 mg as single dose on first day, then 250 mg/d, days 2-5.
Condition: Genital ulcer disease (chanchroid), nongonoccocal urethritis and cervicitis
Dose: Adults PO 1 g as single dose.
Condition: Urethritis and cervicitis (Neisseria gonorrhoeae)
Dose: Adults PO 2 g as single dose. (Note: resistance is a problem.)
Condition: Acute otitis media, community-acquired pneumonia
Dose: Children: Oral suspension 10 mg/kg as single dose on first day, then 5 mg/kg days 2-5. Maximum: 250 mg/d.
Dose: Children >2 years: Oral suspension 12 mg/kg once daily, days 1-5.
Adjustment of Dosage
Kidney disease: None.
Liver disease: None.
Pediatric: Safety and efficacy have not been established for children <6 months for treatment of acute otitis media and <2 years for treatment of pharyngitis/tonsillitis.
Food and Drug Interactions
Food: Should be taken on empty stomach, 1-2 hours after meals.
Pregnancy: Category B.
Lactation: No data available. May appear in breast milk. Best to avoid.
Contraindications: Hypersensitivity to macrolide antibiotics.
Warnings / Precautions: Use with caution in patients with hepatic dysfunction
Clinically Important Drug Interactions
> Drugs that decrease effects/toxicity of macrolides: rifampin, antacids (aluminum, magnesium).
> Macrolides increase effects/toxicity of following drugs: oral anticoagulants, astemizole, benzodiazepines, bromocriptine, buspirone, carbamazepine, cisapride, cyclosporine, digoxin, ergot alkaloids, felodipine, grepafloxacin, statins, pimozide, sparfloxacin, tacrolimus.
> Common: None.
> Severe: pseudomembranous colitis, ventricular arrhythmias, nephritis, cholestatic jaundice, angioedema.
Parameters to Monitor
> Signs and symptoms of superinfection, in particular pseudomembranous colitis.
> Signs and symptoms of renal toxicity.
> Signs and symptoms of hearing impairment. Patients with kidney or liver disease are at highest risk.
Further Useful Info
> Azithromycin has the advantage of improved compliance com-pared with erythromycin because of better tolerability, daily dosage, and shorter course of therapy.
> Often used as outpatient medication and inpatient for community-acquired pneumonia.
> It may be combined with ceftriaxone or cefuroxime for community-acquired pneumonia.
> Increasing resistance in Streptococcus pneumoniae is a problem.
> It is also useful for otitis media, sinusitis, and as single 1-g dose for nongonoccocal urethritis.