Azithromycin

azithromycin (ay zi thro my' sin) Zithromax Pregnancy Category B Drug class

Macrolide antibiotic Therapeutic actions

Bacteriostatic or bactericidal in susceptible bacteria. Indications

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Treatment of lower respiratory tract infections: acute bacterial exacerbations of COPD due to H. influenzae, Moraxella catarrhalis, S. pneumoniae; communityacquired pneumonia due to S. pneumoniae, H. influenzae Treatment of lower respiratory tract infections: streptococcal pharyngitis and 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 and 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

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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

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Mild to moderate acute bacterial exacerbations of COPD, pneumonia, pharyngitis and tonsillitis (as second-line): 500 mg PO single dose on first day,

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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: For prevention, 1,200 mg PO taken once weekly. For treatment, 600 mg/day PO with etambutol.

PEDIATRIC PATIENTS

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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 or tonsillitis: 12 mg/kg/day PO on days 1–5.

Pharmacokinetics Route Oral

Onset Varies

Peak 2.5–3.2 hr

Duration 24 hr

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

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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

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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

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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

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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.