Azithromycin
Azithromycin (Zithromax)
Azithromycin
(az- zith-roh- MY-sin)
Pregnancy Category: B Zithromax (Rx)

Classification: Antibiotic, macrolide

See Also: Anti-Infectives

Action/Kinetics: A macrolide antibiotic derived from erythromycin. The drug acts by binding to the P site of the 50S ribosomal subunit and may inhibit RNA-dependent protein synthesis by stimulating the dissociation of peptidyl t-RNA from ribosomes. Rapidly absorbed and distributed widely throughout the body. Food increases the absorption of azithromycin. Time to reach maximum concentration: 2.2 hr. t 1/2, terminal: 68 hr. A loading dose will achieve steady-state levels more quickly. Mainly excreted unchanged through the bile with a small amount being excreted through the kidneys.

Uses: Adults: Acute bacterial exacerbations of COPD due to Hemophilus influenzae, Moraxella catarrhalis or Streptococcus pneumoniae. Required initial IV therapy in community-acquired pneumonia due to S. pneumoniae, Chlamydia pneumoniae, Mycoplasma pneumoniae, H. influenzae, M. catarrhalis, Legionella pneumophila, and Staphylococcus aureus. Those who can take PO therapy in community-acquired pneumonia due to C. pneumoniae, M. pneumoniae, S. pneumoniae, or H. influenzae. PO for genital ulcer disease in men due to Haemophilus ducreyi. Initial IV therapy in pelvic inflammatory disease due to Chlamydia trachomatis, Neisseria gonorrhoeae or Mycoplasma hominis. As an alternative to first-line therapy to treat streptococcal pharyngitis or tonsillitis due to Streptococcus pyogenes. PO for uncomplicated skin and skin structure infections due to S. aureus, Staphyloccus pyogenes or Streptococcus agalactiae. Abscesses usually require surgical drainage. PO for urethritis and cervicitis due to C. trachomatis or N. gonorrhoeae.
Children: PO for acute otitis media due to H. influenzae, M. catarrhalis, or S. pneumoniae in children over 6 months of age. PO for community-acquired pneumonia due to C. pneumoniae, H. influenzae, M. pneumoniae, or S. pneumoniae in children over 6 months of age. Pharyngitis/tonsillitis due to S. pyogenes in children over 2 years of age who cannot use first-line therapy.

Contraindications: Hypersensitivity to azithromycin, any macrolide antibiotic, or erythromycin. In clients who are not eligible for outpatient PO therapy (e.g., known or suspected bacteremia, immunodeficiency, functional asplenia, nosocomially acquired infections, geriatric or debilitated clients). Use with astemizole, cisapride, or pimozide.

Special Concerns: Use with caution in clients with impaired hepatic or renal function and during lactation. Safety and efficacy for acute otitis media have not been determined in children less than 6 months of age or for pharyngitis/tonsillitis in children less than 2 years of age.

Side Effects: GI: N&V, diarrhea, loose stools, abdominal pain, dyspepsia, anorexia, gastritis, flatulence, melena, mucositis, oral moniliasis, taste perversion, cholestatic jaundice, pseudomembranous colitis. In children, gastritis, constipation, and anorexia have also been noted. CNS: Dizziness, headache, somnolence, fatigue, vertigo. In children, hyperkinesia, agitation, nervousness, insomnia, fever, and malaise have also been noted. CV: Chest pain, palpitations, ventricular arrhythmias (including ventricular tachycardia and torsades de pointes in clients with prolonged QT intervals observed with other macrolides). GU: Monilia, nephritis, vaginitis. Allergic: Angioedema, photosensitivity, rash, anaphylaxis. Hematologic: Leukopenia, neutropenia, decreased platelet count. Miscellaneous: Superinfection, bronchospasm, local IV site reactions. In children, pruritus, urticaria, conjunctivitis, and chest pain have been noted.

Laboratory Test Alterations: Serum CPK, potassium, ALT, GGT, AST, serum alkaline phosphatase, bilirubin, BUN, creatinine, blood glucose, LDH, and phosphate.

Drug Interactions: See also Drug Interactions for Erythromycins . Aluminum- and magnesium-containing antacids / Peak serum levels of azithromycin but not the total amount absorbed Atovaquone / Possible peak serum levels of azithromycin in pediatric HIV-infected clients Cyclosporine / Serum cyclosporine levels R/T metabolism risk of nephrotoxicity and neurotoxicity HMG-CoA reductase inhibitors / Risk of severe myopathy or rhabdomyolysis Phenytoin / Serum phenytoin levels R/T metabolism Pimozide / Possibility of sudden death

How Supplied: Powder for Injection: 500 mg; Powder for Oral Suspension: 100 mg/5mL, 200 mg/5mL, 1 gm/packet; Tablet: 250 mg, 600 mg

Dosage
?Suspension, Tablets Adults: Mild to moderate acute bacterial exacerbations of COPD, mild community-acquired pneumonia, second-line therapy for pharyngitis/tonsillitis; uncomplicated skin and skin structure infections.
Adults and children over 16 years of age: 500 mg as a single dose on day 1 followed by 250 mg once daily on days 2-5 for a total dose of 1.5 g.
Nongonococcal urethritis and cervicitis due to C. trachomatis or genital ulcer disease due to H. ducreyi.
1 g given as a single dose.
Gonococcal urethritis/cervicitis due to N. gonnorheae.
2 g given as a single dose.
Uncomplicated gonococcal infections due to N. gonorrhoeae.
1 g given as a single dose plus a single dose of 400 mg PO cefixime, 125 mg IM ceftriaxone, 500 mg PO ciprofloxacine, or 400 mg PO ofloxacin.
Gonococcal pharyngitis.
1 g given as a single dose plus a single dose of 125 mg IM ceftriaxone, 500 mg ciprofloxacin, or 400 mg ofloxacin.
Chlamydial infections caused by C. trachomatis.
1 g given as a single dose.
?Oral Suspension Pediatric: Otitis media or community-acquired pneumonia.
10 mg/kg (not to exceed 500 mg) on day 1, followed by 5 mg/kg (not to exceed 250 mg/day) on days 2 through 5.
Pediatric: Pharyngitis/tonsillitis.
12 mg/kg once daily for 5 days, not to exceed 500 mg/day.
Chlamydial infections in children caused by C. trachomatis.
Children 45 kg or more and less than 8 years of age or over 8 years of age: 1 g given as a single dose.
?IV Community-acquired pneumonia.
500 mg IV as a single daily dose for at least 2 days followed by a single daily dose of 500 mg PO to complete a 7- to 10-day course of therapy.
Pelvic inflammatory disease.
500 mg IV as a single daily dose for 1 or 2 days followed by a single daily dose of 250 mg PO to complete a 7-day course of therapy.