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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 many Gram-negative bacteria, including those resistant to carbapenems due to certain carbapenemase enzymes.
## Primary Indications
* Complicated intra-abdominal infections (cIAI)
* Complicated urinary tract infections (cUTI), including pyelonephritis
* Hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP)
* For use in patients with limited or no alternative treatment options for Gram-negative infections with known or suspected activity.
## Adult Dosing
The standard dose is **2.5 grams** (aztreonam 2 grams and avibactam 0.5 grams) administered intravenously every **8 hours** over 3 hours.
* **cIAI:** 14 days duration
* **cUTI, including pyelonephritis:** 7 days duration
* **HABP/VABP:** 7 days duration
## Pediatric Dosing
Dosing for pediatric patients varies significantly by age, weight, indication, and renal function. Consult specific pediatric guidelines or product information.
* Children 3 months to < 6 months: 50 mg/kg aztreonam component, 12.5 mg/kg avibactam component IV Q8H.
* Children 6 months to < 2 years: 40 mg/kg aztreonam component, 10 mg/kg avibactam component IV Q8H.
* Children 2 years to < 6 years: 30 mg/kg aztreonam component, 7.5 mg/kg avibactam component IV Q8H.
* Children 6 years to < 12 years: 2 grams aztreonam component, 0.5 grams avibactam component IV Q8H.
* Children 12 years to < 18 years weigh < 40 kg: 2 grams aztreonam component, 0.5 grams avibactam component IV Q8H.
* Children 12 years to < 18 years weigh >= 40 kg: 2 grams aztreonam component, 0.5 grams avibactam component IV Q8H.
## Dose Adjustments
Dose adjustments are primarily based on renal function.
* **CrCl 30 to < 60 mL/min:** 1.5 grams (aztreonam 1.2 grams and avibactam 0.3 grams) IV every 12 hours.
* **CrCl < 30 mL/min:** 1 gram (aztreonam 0.8 grams and avibactam 0.2 grams) IV every 12 hours.
* **Hemodialysis:** Administer dose after hemodialysis on dialysis days. Dose adjustment is necessary. Consult product information for specific recommendations.
## Contraindications
* Known hypersensitivity to aztreonam, avibactam, or any component of the formulation.
## Adverse Effects
Common adverse effects include:
* Diarrhea
* Nausea
* Vomiting
* Headache
* Infusion-related reactions (e.g., phlebitis, pain at injection site)
* Elevated liver enzymes (AST, ALT)
* Rash
* Fever
Serious adverse effects include:
* Hypersensitivity reactions (anaphylaxis)
* Clostridioides difficile-associated diarrhea (CDAD)
* Seizures (rarely associated with beta-lactams, especially in renal impairment)
## Key Drug Interactions
* **Probenecid:** May increase plasma concentrations of aztreonam.
* **Valproic acid:** Aztreonam may decrease valproic acid concentrations, potentially leading to reduced efficacy; consider alternative antibiotics or closer monitoring of valproic acid levels.
## Monitoring
* Monitor for signs and symptoms of hypersensitivity reactions.
* Assess for development of CDAD.
* Monitor renal function regularly, especially in patients with pre-existing renal impairment or those receiving nephrotoxic agents.
* Monitor liver function tests.
* Monitor for clinical improvement of infection.
## Clinical Pearls
* Aztreonam is stable in the presence of many beta-lactamases, but avibactam is necessary to inhibit certain Extended-Spectrum Beta-Lactamases (ESBLs), KPC, OXA, and NDM carbapenemases.
* Aztreonam is resistant to hydrolysis by most beta-lactamases but is susceptible to hydrolysis by certain carbapenemases. Avibactam inhibits a broad spectrum of beta-lactamases, including carbapenemases.
* The combination provides activity against *Pseudomonas aeruginosa*, Enterobacteriaceae, and *Stenotrophomonas maltophilia*.
* Ensure proper diagnosis and susceptibility testing.
* Administer as an intravenous infusion over 3 hours.
* Consult local antibiograms for resistance patterns.
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*Disclaimer: This information is intended for healthcare professionals and should not substitute for professional medical advice. Always verify current prescribing information and specific institutional protocols before administering any medication.*
