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Sunday, February 6, 2011

Azithromycin

Posted by Sampil 9:52 PM, under | No comments

azithromycin
(ay zi thro my' sin)
Zithromax, Zmax

Pregnancy Category B

Drug class
Macrolide antibiotic

Therapeutic actions
Bacteriostatic or bactericidal in susceptible bacteria.

Indications
·        Treatment of lower respiratory 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 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 acute sinusitis
·        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
·        Treatment of patients with mild to moderate acute bacterial sinusitis caused by H. influenzae, Moracellis catarrhalis, Streptococcus pneumoniae (Zmax)
·        Treatment of mild to moderate community-acquired pneumonia caused by Chlamydophila pneumoniae, H. influenzae, Mycoplasma pneumoniae, Streptococcus pneumoniae (Zmax)
·        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, 500, 600 mg; powder for injection—500 mg; powder for oral suspension—100 mg/5 mL, 200 mg/5 mL, 1 g/packet; bottles—2 g to be reconstituted with 60 mL water (Zmax)
Dosages
ADULTS
·        Mild to moderate acute bacterial exacerbations of COPD, pneumonia, pharyngitis and 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. trachomatis: 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.
·        Acute sinusitis: 500 mg/day PO for 3 days.
·        Mild to moderate acute bacterial sinusitis, community-acquired pneumonia: 2 g/day PO as a single dose (Zmax).
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 or tonsillitis: 12 mg/kg/day PO on days 1–5.
·        Acute sinusitis: 10 mg/kg/day PO for 3 days.

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

Metabolism: T1/2: 11–48 hr
Distribution: Crosses placenta; enters breast milk
Excretion: Bile, urine—unchanged

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
·        Decreased serum levels and effectiveness of azithromycin with aluminum and magnesium-containing antacids
·        Possible increased effects of theophylline
·        Possible increased anticoagulant effects of warfarin
·        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, LFTs, 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.
·        Prepare Zmax by adding 60 mL water to bottle, shake well.
·        Counsel patients being treated for STDs about appropriate precautions and additional therapy.

Teaching points
·        Take the full course prescribed. Do not take with antacids. Tablets and oral suspension can be taken with or without food.
·        Prepare Zmax by adding 60 mL (1/4 cup) water to bottle, shake well, drink all at once.
·        You may experience these side effects: 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.

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