Aztreonam
Also known as: Azactam · Cayston · Monobac · Aztreotic · Azenam · Primbactam · Trezam · Urobactam · Aztreonamum · Azthreonam · Atstreonaami · SQ-26776
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Serious gram-negative infections | 30 mg/kg | IM or IV | q6-8h | — | 🌎 NA |
- Serious gram-negative infections: Anecdotal dosing suggestion based on the human pediatric dose. Aztreonam has a shorter half-life in dogs but is about half as bound to plasma proteins compared to humans.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Aztreonam is a monobactam injectable antibiotic primarily utilized for its strong activity against a variety of aerobic and facultative gram-negative bacteria.
- Spectrum of Activity: Highly effective against Citrobacter, Enterobacter, E. coli, Klebsiella, Proteus, Pseudomonas, and Serratia.
- Clinical Pearl: It is not clinically efficacious against gram-positive or anaerobic bacteria.
- Clinical Utility: Often considered for serious gram-negative infections when traditional choices like aminoglycosides or fluoroquinolones are ineffective or relatively contraindicated (e.g., due to nephrotoxicity concerns).
- Exhibits excellent tissue penetration and generally has a low toxic potential, though clinical experience and pharmacokinetic data in veterinary target species remain limited.
Mechanism of action
Aztreonam is a bactericidal antibiotic.
- It selectively binds to penicillin-binding protein-3 (PBP-3) in susceptible bacteria.
- Binding to PBP-3 → inhibits bacterial cell wall synthesis → results in cell lysis and death.
- It is highly stable against the hydrolytic effects of bacterial beta-lactamases and, unlike many other beta-lactam antibiotics, does not induce beta-lactamase activity.
- Synergy: Can exhibit synergistic effects against Pseudomonas aeruginosa and other gram-negative bacilli when used concurrently with aminoglycosides.
Safety & warnings
Contraindications
- Documented severe hypersensitivity to aztreonam
Adverse effects
- Hypersensitivity reactions
- Gastrointestinal effects (bacterial overgrowth, pseudomembranous colitis, diarrhea)
- Pain and/or swelling after IM injection
- Phlebitis after IV administration
- Transient increases in liver enzymes, serum creatinine, and coagulation indices
Precautions
Use cautiously in patients with serious renal or liver dysfunction; dosage adjustment may be needed. Aztreonam may cause false-positive urine glucose determinations when using cupric sulfate solutions (e.g., Benedict's Solution, Clinitest). Tests utilizing glucose oxidase are not affected.
Drug interactions
Can reduce the renal tubular secretion of aztreonam, thereby maintaining higher systemic levels for a longer period of time. This potential 'beneficial' interaction requires further investigation in veterinary patients.
Monitoring
- Clinical efficacy
- Signs of toxicity or adverse effects
- Renal and hepatic function in compromised patients
Pharmacokinetics
Half-life
Absorption
In dogs, after a 20 mg/kg IM dose, peak plasma levels of approximately 40 mcg/mL occur in about 20 minutes.
Distribution
Serum protein binding in dogs is about 20-30% (compared to 65% in humans). High tissue levels are found in the kidney (~2.5x plasma levels). Liver concentrations approximate plasma levels; lower levels are found in the lung and spleen. Crosses the placenta and is detected in fetal circulation. Excreted in breast milk at ~1% of serum levels.
Metabolism
Minimal hepatic metabolism.
Elimination
Primarily (80%) excreted unchanged in the urine in dogs.
Overdose
There is little reason for concern in patients with adequate renal function. The IV LD50 for mice is 3.3 g/kg. Hemodialysis or peritoneal dialysis may be used to clear aztreonam from the circulation.
Available products
Formulations
- Injection (lyophilized cake or powder for solution)
- Powder for inhalation solution
Human-labeled
- Aztreonam Injection (lyophilized cake or powder for solution): 500 mg, 1 g, 2 g single-dose vials and infusion bottles
- Aztreonam Powder (lyophilized) for inhalation solution: 75 mg
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store commercially available powder for reconstitution at room temperature (15°-30°C). Reconstituted IM solutions are stable for 48 hours at room temperature, or 7 days if refrigerated. Intravenous solutions not exceeding 20 mg/mL are stable for 48 hours at room temperature, or 7 days if refrigerated. Solutions may be colorless or light straw yellow; upon standing, a light pink color may develop which does not affect the drug's potency.
Client information
Important: This medication should only be administered by veterinary professionals.
- Because of the frequent dosing intervals required (every 6-8 hours), this drug is best administered to inpatients in a hospital setting.
- If your pet is nursing, the drug is generally considered safe, but monitor the nursing offspring for signs of antibiotic-associated diarrhea.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.