azithromycin
(ay zi thro my' sin)
Zithromax

Pregnancy Category B

Drug class
Macrolide antibiotic

Therapeutic actions
Bacteriostatic or bactericidal in susceptible bacteria.

Indications
· Treatment of lower respiratory tract infections: acute bacterial exacerbations of COPD due to H. influenzae, Moraxella catarrhalis, S. pneumoniae; community-acquired pneumonia due to S. pneumoniae, H. influenzae
· Treatment of lower respiratory tract infections: streptococcal pharyngitis/tonsillitis due to Streptococcus pyogenes in those who cannot take penicillins
· Treatment of uncomplicated skin infections due to Staphylococcus aureus, S. pyogenes, Streptococcus agalactiae
· Treatment of nongonococcal urethritis and cervicitis due to C. trachomatis; treatment of PID
· Treatment of otitis media caused by H. influenzae, M. catarrhalis, S. pneumoniae in children > 6 mo
· Treatment of pharyngitis/tonsillitis in children > 2 yr who cannot use first-line therapy
· Prevention and treatment of disseminated Mycobacterium avium complex (MAC) in patients with advanced AIDS
· Unlabeled uses: uncomplicated gonococcal infections caused by N. gonorrhoeae; gonococcal pharyngitis caused by N. gonorrhoeae; chlamydial infections caused by C. trachomatis; prophylaxis after sexual attack

Contraindications and cautions
· Contraindicated with hypersensitivity to azithromycin, erythromycin, or any macrolide antibiotic.
· Use cautiously with gonorrhea or syphilis, pseudomembranous colitis, hepatic or renal impairment, lactation.

Available forms
Tablets--250, 600 mg; powder for injection--500 mg; powder for oral suspension--100 mg/5 mL, 200 mg/5 mL, 1 g/packet
Dosages
ADULTS
· Mild to moderate acute bacterial exacerbations of COPD, pneumonia, pharyngitis/tonsillitis (as second-line): 500 mg PO single dose on first day, followed by 250 mg PO daily on days 2–5 for a total dose of 1.5 g or 500 mg/day PO for 3 days.
· Nongonococcal urethritis and cervicitis due to C. trachomati: A single 1-g PO dose.
· Gonococcal urethritis and cervicitis: A single dose of 2 g PO.
· Disseminated MAC infections:
Prevention: 1,200 mg PO taken once weekly.
Treatment: 600 mg/day PO with etambutol.
PEDIATRIC PATIENTS
· Otitis media: Initially 10 mg/kg PO as a single dose, then 5 mg/kg on days 2–5 or 30 mg/kg PO as a single dose.
· Community-acquired pneumonia: 10 mg/kg PO as a single dose on first day, then 5 mg/kg PO on days 2–5.
· Pharyngitis/tonsillitis: 12 mg/kg/day PO on days 1–5.

Pharmacokinetics
Route
Onset
Peak
Duration
Oral
Varies
2.5–3.2 hr
24 hr


Metabolism: T1/2: 11–48 hr
Distribution: Crosses placenta; passes into breast milk
Excretion: Unchanged in biliary excretion and urine

Adverse effects
· CNS: Dizziness, headache, vertigo, somnolence, fatigue
· GI: Diarrhea, abdominal pain, nausea, dyspepsia, flatulence, vomiting, melena, pseudomembranous colitis
· Other: Superinfections, angioedema, rash, photosensitivity, vaginitis

Interactions
Drug-drug
· Decreased serum levels and effectiveness of azithromycin with aluminum and magnesium-containing antacids
· Possible increased effects of theophylline
· Possible increased anticoagulant effects of warfarin
Drug-food
· Food greatly decreases the absorption of azithromycin

Nursing considerations
Assessment
· History: Hypersensitivity to azithromycin, erythromycin, or any macrolide antibiotic; gonorrhea or syphilis, pseudomembranous colitis, hepatic or renal impairment, lactation
· Physical: Site of infection; skin color, lesions; orientation, GI output, bowel sounds, liver evaluation; culture and sensitivity tests of infection, urinalysis, liver and renal function tests

Interventions
· Culture site of infection before therapy.
· Administer on an empty stomach--1 hr before or 2–3 hr after meals. Food affects the absorption of this drug.
· Counsel patients being treated for STDs about appropriate precautions and additional therapy.

Teaching points
· Take this drug on an empty stomach--1 hr before or 2–3 hr after meals; it should never be taken with food. Take the full course prescribed. Do not take with antacids.
· These side effects may occur: stomach cramping, discomfort, diarrhea; fatigue, headache (medication may help); additional infections in the mouth or vagina (consult with health care provider for treatment).
· Report severe or watery diarrhea, severe nausea or vomiting, rash or itching, mouth sores, vaginal sores.

Adverse effects in Italic are most common; those in Bold are life-threatening.