Azithromycin: Action Uses Interactions Administration Dosage Nursing Considerations by NJE

Uses of Azithromycin

Azithromycin:Treatment of susceptible infections due to Chlamydia pneumoniae, C.trachomatis, H. influenzae, Legionella, M. catarrhalis, Mycoplasma pneumoniae, N. gonorrhoeae, S. aureus., S. pneumoniae, S. pyogenes, including mild to moderate infections of upper respiratory tract (pharyngitis, tonsillitis), lower respiratory tract (acute bacterial exacerbations, COPD, pneumonia), uncomplicated skin and skin structure infections, sexually transmitted diseases (nongonococcal urethritis, cervicitis due to C. trachomatis), chancroid. Prevents disseminated Mycobacterium avium complex (MAC). Treatment of mycoplasma pneumonia, community-acquired pneumonia, pelvic inflammatory disease (PID). Prevention/treatment of MAC in pts with advanced HIV infection. 

CLASSIFICATION

PHARMACOTHERAPEUTIC: Macrolide.

CLINICAL: Antibiotic.

OFF LABEL: Prophylaxis of endocarditis. Prevention of pulmonary exacerbations in pts with cystic fibrosis. 

Ophthalmic: Treatment of bacterial conjunctivitis caused by susceptible infections due to H. influenzae, S. aureus, S. mitis, S. pneumoniae. Prevention of pulmonary exacerbations in pts with cystic fibrosis.

Precaution for Azithromycin

Contraindications: Hypersensitivity to azithromycin or other macrolide antibiotics. History of cholestatic jaundice/hepatic impairment associated with prior azithromycin therapy. 

Cautions: Hepatic/renal impairment, myasthenia gravis, hepatocellular and/or cholestatic hepatitis (with or without jaundice), hepatic necrosis. May prolong QT interval. 

Action of Azithromycin

Binds to ribosomal receptor sites of susceptible organisms, inhibiting RNA dependent protein synthesis. Therapeutic Effect: Bacteriostatic or bactericidal, depending on drug dosage.

Pharmacokinetics of Azithromycin

Rapidly absorbed from GI tract. Protein binding: 7%–50%. Widely distributed.Metabolized in the liver. Excreted primarily by biliary excretion. Half-life: 68 hrs.

Lifespan considerations

Pregnancy/Lactation: Unknown if distributed in breast milk. Children: Safety and efficacy not established in pts younger than 16 yrs for IV use and younger than 6 mos for oral use. Elderly: No age-related precautions in those with normal renal function.

Interactions of Azithromycin

DRUG: Aluminum/magnesium-containing antacids may decrease concentration (give 1 hr before or 2 hrs after antacid). May increase levels of amiodarone, cycloSPORINE, dronedarone, QT-prolonging medications, thioridazine. toremifene, ziprasidone. QUEtiapine may increase concentration. 

HERBAL: None significant. FOOD: None known.

LAB VALUES: May increase serum creatine phosphokinase (CPK), ALT, AST, bilirubin, LDH, potassium.

Availability (Rx)

Injection, Powder for Reconstitution (Zithromax): 500 mg. 

Ophthalmic Solution (AzaSite): 1%. 

Suspension, Oral (Zithromax): 100 mg/5 mL, 200mg/5 mL.

Suspension, Oral (Extended-Release [Zmax]): 2-g single-dose packet. 

Tablets: 250 mg, 500 mg, 600 mg.

Administration/handling of Azithromycin

IV

Reconstitution

• Reconstitute each 500-mg vial with 4.8 mL Sterile Water for Injection to provide concentration of 100 mg/mL.

• Shake well to ensure dissolution.

• Further dilute with 250 or 500 mL 0.9% NaCl or D5W to provide final concentration of 2 mg/mL with 250 mL diluent or 1 mg/mL with 500 mLdiluent.

Rate of Administration

• Infuse over 60 min (2 mg/mL). Infuse over 3 hrs (1 mg/mL).

Storage

• Store vials at room temperature.

• Following reconstitution, diluted solution is stable for 24 hrs at room temperature or 7 days if refrigerated.

PO (Immediate-Release Suspension)

• Give tablets without regard to food.

• May store suspension at room temperature. Stable for 10 days after reconstitution. 

PO (Extended-Release Suspension)

• Do not administer oral suspension with food. Give at least 1 hr before or 2 hrs after meals.

• Give Zmax within 12 hrs of reconstitution.

• Give tablets with food to decrease GI effects.

PO

• Tablets: May give with food to decrease GI effects.

Ophthalmic

• Place a gloved finger on the lower eyelid and pull out until a pocket is formed between eye and lower lid.

• Place the prescribed number of drops into the pocket.

• Instruct pt to close eye gently for 1 to 2 min (so that medication will not be squeezed out of sac) and to apply digital pressure to lacrimal sac at inner canthus for 1 min to minimize systemic absorption.

IV incompatibilities of Azithromycin

CefTRIAXone (Rocephin), ciprofloxacin (Cipro), famotidine (Pepcid), furosemide (Lasix), ketorolac (Toradol), levoFLOXacin (Levaquin), morphine, piperacillin/tazobactam (Zosyn), potassium chloride.

IV Compatibilities

Ceftaroline (Teflaro), doripenem (Doribax), ondansetron (Zofran), tigecycline(Tygacil), diphenhydrAMINE (Benadryl).

Indications/routes/dosage of Azithromycin

Usual Dosage Range

PO: ADULTS, ELDERLY: 250–600 mg once daily or 1–2 g as a single dose. (Zmax): 2 g as a single dose.

CHILDREN 6 MOS AND OLDER: 5–12 mg/kg(maximum: 500 mg) once daily or 30 mg/kg (maximum: 1,500 mg) as single dose. (Zmax):60 mg/kg as a single dose. 

NEONATES: 10–20 mg/kg once daily.

IV: ADULTS, ELDERLY: 250–500 mg once daily CHILDREN, NEONATES: 10 mg/kg once daily.

Mild to Moderate Respiratory Tract, Skin, Soft Tissue Infections

PO: ADULTS, ELDERLY: 500 mg day 1, then 250 mg days 2–5.

MAC Prevention

PO: ADULTS, ELDERLY: 1,200 mg once weekly. CHILDREN: 20 mg/kg
once weekly. Maximum: 1,200 mg/dose.

MAC Treatment

PO: ADULTS, ELDERLY: 600 mg/day with ethambutol. CHILDREN: 10–12 mg/kg/day (maximum: 500 mg) with ethambutol.

Otitis Media

PO: CHILDREN 6 MOS AND OLDER: 30 mg/kg as single dose (maximum:1,500 mg) or 10 mg/kg/day for 3 days (maximum: 500 mg) or 10 mg/kg on day 1 (maximum: 500 mg), then 5 mg/kg on days 2–5 (maximum: 250 mg).

Pharyngitis, Tonsillitis

PO: ADULTS, ELDERLY, CHILDREN: 12 mg/kg (maximum: 500 mg) on day 1, then 6 mg/kg (maximum: 250 mg) on days 2–5.

Pneumonia, Community-Acquired

PO (Zmax): ADULTS, ELDERLY: 2 g as a single dose.

PO: ADULTS, ELDERLY, CHILDREN 16 YRS AND OLDER: 500 mg on day 1, then 250 mg on days 2–5 or 500 mg/day IV for 2 days, then 500 mg/day PO to complete course of therapy.

CHILDREN 6 MOS–15 YRS: 10 mg/kg on day 1 (maximum: 500 mg), then 5 mg/kg (maximum: 250 mg) on days 2–5.

Dosage in Renal/Hepatic Impairment: Use caution.

Bacterial Conjunctivitis

Ophthalmic: ADULTS, ELDERLY: 1 drop in affected eye twice daily for 2 days, then 1 drop once daily for 5 days.

Side effects of Azithromycin

Occasional: Systemic: Nausea, vomiting, diarrhoea, abdominal pain. Ophthalmic: Eye irritation. Rare: Systemic: Headache, dizziness, allergic reaction.

Adverse effects/toxic reactions of Azithromycin

Antibiotic-associated colitis, other superinfections may result from the altered bacterial balance in the GI tract. Acute interstitial nephritis, hepatotoxicity occur rarely.

Nursing considerations of Azithromycin

Baseline assessment

Question for the history of hepatitis, allergies to azithromycin, erythromycins. Assess for infection (WBC count, appearance of wound, evidence of fever).

Intervention/evaluation

Check for GI discomfort, nausea, vomiting. Monitor daily pattern of bowel activity and stool consistency. Monitor LFT, CBC. Assess for hepatotoxicity: malaise, fever, abdominal pain, GI disturbances. Be alert for superinfection: fever, vomiting, diarrhoea, anal/genital pruritus, oral mucosal changes (ulceration, pain, erythema).

Patient/family teaching

• Continue therapy for the full length of treatment.

• Avoid concurrent administration of aluminium- or magnesium-containing antacids.

• Bacterial conjunctivitis: Do not wear contact lenses.