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# Aztreonam-avibactam (Avycaz)
## Overview
Aztreonam-avibactam is a combination of aztreonam, a monobactam antibiotic, and avibactam, a beta-lactamase inhibitor. It is active against Gram-negative bacteria, including those producing certain carbapenemase enzymes.
## Primary Indications
* Complicated intra-abdominal infections (cIAI)
* Complicated urinary tract infections (cUTI), including pyelonephritis
* Hospital-acquired pneumonia (HAP), including ventilator-associated pneumonia (VAP)
Used in combination with metronidazole for cIAI.
## Adult Dosing
* **cIAI, cUTI, HAP/VAP:** 2.5 grams (aztreonam 2 grams / avibactam 0.5 grams) administered intravenously every 8 hours for 5 to 14 days.
* For cIAI, administer concurrently with metronidazole.
* Duration of therapy depends on the indication and severity of infection.
## Pediatric Dosing
Dosing in pediatric patients is less established and may depend on local protocols:
* **cUTI:** 100 mg/kg (aztreonam component) / 12.5 mg/kg (avibactam component) administered intravenously every 8 hours. Maximum dose is typically 2.5 grams per dose.
* **cIAI, HAP/VAP:** 125 mg/kg (aztreonam component) / 31.25 mg/kg (avibactam component) administered intravenously every 8 hours. Maximum dose is typically 2.5 grams per dose.
* Duration of therapy varies. Consultation with infectious disease or pediatric infectious disease specialist is recommended.
## Dose Adjustments
* **Renal Impairment (CrCl ≥ 60 mL/min):** No adjustment needed.
* **Renal Impairment (CrCl 30-59 mL/min):** 1.5 grams (aztreonam 1.2 grams / avibactam 0.3 grams) every 8 hours.
* **Renal Impairment (CrCl ≤ 29 mL/min):** 1 gram (aztreonam 0.8 grams / avibactam 0.2 grams) every 8 hours.
* **Hemodialysis:** Dosing requires careful consideration based on timing with dialysis sessions; consult product information for specific recommendations.
* **Hepatic Impairment:** No dosage adjustment necessary for mild to moderate hepatic impairment. Use with caution in severe hepatic impairment.
## Contraindications
* Known hypersensitivity to aztreonam, avibactam, or any component of the formulation.
## Adverse Effects
Common adverse effects include:
* Diarrhea
* Nausea
* Vomiting
* Headache
* Increased liver enzymes (AST, ALT)
* Rash
* Infusion-related reactions
Less common but serious:
* Hypersensitivity reactions, including anaphylaxis
* Clostridioides difficile-associated diarrhea
## Key Drug Interactions
* **Probenecid:** May increase plasma concentrations of aztreonam. Avoid concomitant use if possible.
* **Valproic Acid:** Aztreonam may decrease valproic acid concentrations, potentially leading to loss of seizure control. Monitor valproic acid levels and consider alternative antibiotics or increased valproic acid dosing.
## Monitoring
* Assess for signs and symptoms of infection.
* Monitor for hypersensitivity reactions.
* Monitor renal function, especially in patients with pre-existing renal impairment or those receiving nephrotoxic agents.
* If co-administered with valproic acid, monitor valproic acid serum concentrations.
## Clinical Pearls
* Aztreonam-avibactam is typically reserved for infections caused by Gram-negative organisms that are resistant to other treatment options, including carbapenems.
* When treating cIAI, it must be administered with metronidazole.
* Hypersensitivity reactions can occur, particularly in patients with a history of penicillin or other beta-lactam allergies. While aztreonam is a monobactam, cross-reactivity with penicillins is rare but possible. Careful patient history is essential.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional guidelines for complete details and to ensure patient safety.*
