Classifications: antibiotic; beta-lactam antibiotic;
Therapeutic: antibiotic

Prototype: Imipenem-cilastatin
Pregnancy Category: B


500 mg, 1 g, 2 g vials


Differs structurally from other beta-lactam antibiotics (penicillins and cephalosporins) in having a monocyclic rather than a bicyclic nucleus. Acts by inhibiting synthesis of bacterial cell wall by preferentially binding to specific penicillin-binding proteins (PBP) in the bacterial cell wall.

Therapeutic Effect

Highly resistant to beta-lactamases and does not readily induce their formation. Spectrum of activity limited to aerobic, gram-negative bacteria.


Gram-negative infections of urinary tract, lower respiratory tract, skin and skin structures; and for intraabdominal and gynecologic infections, septicemia, and as adjunctive therapy for surgical infections. Often used in combination with other antibiotics active against gram-positive and anaerobic bacteria in mixed infections.


Lactation, viral infections.

Cautious Use

History of hypersensitivity reaction to penicillin, cephalosporins, or to other drugs; impaired renal or hepatic function, elderly; pregnancy (category B).

Route & Dosage

Urinary Tract Infection
Adult: IV/IM 0.5–1 g q8–12h

Moderate to Severe Infections
Adult: IV/IM 1–2 g q8–12h (max: 8 g/24 h)
Child: IV 30 mg/kg/d q6–8h

Cystic Fibrosis
Child: IV/IM 50 mg/kg q6–8h (max: 8 g/d)

Renal Impairment
Clcr 10–30 mL/min: reduce dose 50%; <10mL/min: reduce dose by 75%
Hemodialysis: Reduce dose to 12.5% and give after hemodialysis


  • Reconstitute with at least 3 mL of diluent per gram of drug for IM injection. Immediately and vigorously shake vial to dissolve. Suitable diluents include sterile water for injection; bacteriostatic water for injection (with benzyl alcohol and propyl parabens); NS 0.9% for injection.
  • Give IM injections deeply into large muscle mass such as the upper outer quadrant of the gluteus maximus or lateral thigh. Rotate injection sites.

Verify correct IV concentration and rate of infusion/injection with physician before giving to neonates, infants, and children.

PREPARE: Direct: ?? Reconstitute a single dose with 6–10 mL of sterile water for injection. ??Immediately shake vial until solution is dissolved. May be given direct IV as prepared or further diluted for IV infusion.??Reconstituted solutions are colorless to light straw yellow and turn slightly pink on standing. Intermittent: Each gram of reconstituted aztreonam must be further diluted in at least 50 mL of D5W, NS, or other solution approved by manufacturer to yield a concentration not to exceed 20 mg/mL.  

ADMINISTER: Direct: Give over 3–5 min.  Intermittent: Give over 20–60 min through Y-site.  

INCOMPATIBILITIES Solution/additive: Ampicillin, metronidazole, nafcillin. Y-site: Acyclovir, amphotericin B, amphotericin b cholesteryl complex, amsacrine, azithromycin, chlorpromazine, daunorubicin, ganciclovir, lansoprazole, lorazepam, metronidazole, mitomycin, mitoxantrone, streptozocin.

Adverse Effects (≥1%)

Body as a Whole: Hypersensitivity (urticaria, eosinophilia, anaphylaxis). CNS: Headache, dizziness, confusion, paresthesias, insomnia, seizures. GI: Nausea, diarrhea, vomiting, elevated liver function tests. Hematologic: Eosinophilia. Special Senses: Tinnitus, nasal congestion, sneezing, diplopia. Skin: Rash, purpura, erythema multiforme, exfoliative dermatitis, diaphoresis; petechiae, pruritus. Other: Local reactions (phlebitis, thrombophlebitis (following IV), pain at injection sites), superinfections (gram-positive cocci), vaginal candidiasis.

Diagnostic Test Interference

Aztreonam may cause transient elevations of liver function tests, increases in PT and PTT, minor changes in Hgb, and positive Coombs' test.


Drug: Imipenem-cilastatin, cefoxitin may be antagonistic, probenecid slows renal elimination of aztreonam.


Peak: 1 h IM. Distribution: Widely distributed including synovial and blister fluid, bile, bronchial secretions, prostate, bone, and CSF; crosses placenta; distributed into breast milk in small amounts. Metabolism: Not extensively metabolized. Elimination: 60–70% in urine within 24 h. Half-Life: 1.6–2.1 h.

Nursing Implications

Assessment & Drug Effects

  • Lab tests: Obtain baseline C&S test prior to initiation of therapy. Start drug pending results.
  • Baseline and periodic renal function tests, particularly in older adults and in those with history of renal impairment.
  • Inspect IV injection sites daily for signs of inflammation. Pain and phlebitis occur in a significant number of patients.

Patient & Family Education

  • Determine previous hypersensitivity reactions to penicillins, cephalosporins, and other allergens prior to therapy.
  • Monitor for S&S of opportunistic infections (diarrhea, rectal or vaginal itching or discharge, fever, cough) and promptly report onset to physician. Overgrowth of nonsusceptible organisms, particularly staphylococci, streptococci, and fungi, is a threat, especially in patients receiving prolonged or repeated therapy.
  • Note: IV therapy may cause a change in taste sensation. Report interference with eating.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2022 Last Updated On: 09/22/2022 (0)
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