Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
Cefazolin vs AVYCAZ
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Cefazolin is a first-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), thereby inhibiting transpeptidation and disrupting peptidoglycan cross-linking. This leads to cell lysis and death primarily in susceptible gram-positive bacteria.
AVYCAZ is a combination of ceftazidime, a cephalosporin beta-lactam antibiotic, and avibactam, a non-beta-lactam beta-lactamase inhibitor. Ceftazidime inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis. Avibactam protects ceftazidime from degradation by certain beta-lactamases, including Ambler class A, class C, and some class D enzymes.
Perioperative prophylaxis (surgical prophylaxis),Respiratory tract infections,Urinary tract infections,Skin and soft tissue infections,Biliary tract infections,Bone and joint infections,Genital infections,Septicemia,Endocarditis (off-label)
Complicated intra-abdominal infections (c IAI) in combination with metronidazole,Complicated urinary tract infections (c UTI) including pyelonephritis,Hospital-acquired and ventilator-associated bacterial pneumonia (HABP/VABP)
1-2 g IV/IM every 6-8 hours; maximum 12 g/day.
1 vial (ceftazidime 2g and avibactam 0.5g) IV over 2 hours every 8 hours.
1.8 hours in normal renal function; extends to 30–70 hours in end-stage renal disease (Cr Cl <10 m L/min).
Ceftazidime: ~2.8 hours; avibactam: ~2.7 hours. Extended in renal impairment (e.g., Cr Cl <50 m L/min requires dose adjustment).
Cefazolin undergoes minimal hepatic metabolism; it is primarily excreted unchanged in the urine via glomerular filtration and tubular secretion. The drug is not significantly metabolized by the liver.
Ceftazidime is primarily excreted unchanged by the kidneys via glomerular filtration. Avibactam is also primarily eliminated renally and undergoes minimal metabolism. The metabolism of both components is not significantly mediated by cytochrome P450 enzymes.
Renal: 80–90% unchanged via glomerular filtration and tubular secretion; biliary: <1%; fecal: negligible.
Ceftazidime: primarily renal (80-90% unchanged); avibactam: primarily renal (85-95% unchanged). Fecal excretion <1%.
80% bound to albumin.
Ceftazidime: ~10% bound to albumin; avibactam: ~8% bound to human plasma proteins.
0.12–0.14 L/kg; approximates extracellular fluid volume, indicating low tissue penetration.
Ceftazidime: ~0.19 L/kg; avibactam: ~0.29 L/kg. Indicates extensive distribution into extracellular fluid.
Intramuscular: 100% (complete absorption).
IV only; bioavailability is 100%.
Cr Cl >55 m L/min: no adjustment; Cr Cl 35-54 m L/min: 1-2 g every 8 hours; Cr Cl 11-34 m L/min: 500 mg-1 g every 12 hours; Cr Cl ≤10 m L/min: 500 mg-1 g every 24-48 hours.
Cr Cl 31-50 m L/min: 1 vial IV q8h; Cr Cl 16-30 m L/min: 1 vial IV q12h; Cr Cl 6-15 m L/min: 1 vial IV q24h; Cr Cl ≤5 m L/min: 1 vial IV q48h.
No dosage adjustment required for hepatic impairment.
No dosage adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C).
50-100 mg/kg/day IV/IM divided every 8 hours; severe infections: 100 mg/kg/day divided every 6-8 hours.
Not approved for pediatric patients under 18 years of age.
No specific adjustment based solely on age; dose adjustment based on renal function per Cr Cl.
Dose based on renal function, as per adult renal adjustment; no specific age-related adjustments.
No FDA black box warning.
No black box warning for AVYCAZ.
Hypersensitivity reactions (including anaphylaxis) may occur; cross-allergenicity among cephalosporins and penicillins is possible.,Clostridioides difficile-associated diarrhea (CDAD) can occur with antibiotic use.,Dosage adjustment required in patients with renal impairment due to predominantly renal elimination.,Prolonged use may result in overgrowth of nonsusceptible organisms (e.g., Candida, Pseudomonas).,Seizures may occur with high doses, especially in patients with renal impairment.
Hypersensitivity: Serious and occasionally fatal hypersensitivity reactions (anaphylaxis) have been reported in patients receiving beta-lactam antibiotics.,Clostridioides difficile-associated diarrhea (CDAD): Has been reported with nearly all antibacterial agents and may range in severity from mild diarrhea to fatal colitis.,Direct Coombs test seroconversion: Positive direct Coombs test may develop during treatment, potentially interfering with crossmatching.,Central nervous system (CNS) adverse reactions: Including seizures, encephalopathy, and myoclonus have been reported, particularly in patients with renal impairment or higher doses.,Renal impairment: Dose adjustment required based on creatinine clearance.,Hepatotoxicity: Elevations of liver enzymes have been observed.,Nephrotoxicity: Concurrent use with nephrotoxic agents may increase risk.
Known hypersensitivity to cefazolin or any cephalosporin antibiotic,Immediate-type hypersensitivity reaction to penicillins (relative caution due to potential cross-allergenicity)
Known hypersensitivity to ceftazidime, avibactam, or other cephalosporins,Severe hypersensitivity (e.g., anaphylaxis) to any other beta-lactam antibacterial agents
No significant food interactions. Alcohol should be avoided during treatment and for at least 72 hours after last dose due to potential disulfiram-like reaction (nausea, vomiting, flushing).
No significant food interactions. However, alcohol should be avoided due to potential disulfiram-like reaction (nausea, vomiting, flushing, headache).
Cefazolin is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, and adequate, well-controlled studies in pregnant women are lacking. Generally considered safe throughout pregnancy; no known teratogenic effects in the first trimester. Use only if clearly needed.
AVYCAZ (ceftazidime-avibactam) is classified as FDA Pregnancy Category B. Animal reproduction studies in rats and rabbits at doses up to 1.6 times the human dose revealed no evidence of fetal harm. However, there are no adequate and well-controlled studies in pregnant women. Ceftazidime crosses the placenta. Risk cannot be ruled out; use only if clearly needed.
Cefazolin is excreted into breast milk in low concentrations (M/P ratio approximately 0.02–0.05). It is considered compatible with breastfeeding; potential for infant gut flora alteration but unlikely to cause adverse effects. Use caution in neonates with hyperbilirubinemia or glucose-6-phosphate dehydrogenase deficiency.
Ceftazidime is excreted in human milk in low concentrations; avibactam excretion is unknown. The M/P ratio for ceftazidime is approximately 0.02. Caution is advised due to potential disruption of infant gut flora. Consider benefits of breastfeeding versus risk of infant exposure.
Pregnancy increases volume of distribution and renal clearance, potentially lowering serum concentrations. Standard dosing (1–2 g every 8 hours for most infections) is generally adequate; for serious infections, consider higher doses (up to 12 g/day) or more frequent intervals (every 6 hours) in the third trimester. Adjust based on therapeutic response and renal function.
No specific dose adjustments are recommended for pregnancy. Physiological changes in pregnancy (e.g., increased volume of distribution, enhanced renal clearance) may alter pharmacokinetics, but data are insufficient to recommend routine dose modification. Monitor clinical response and consider therapeutic drug monitoring if available.
Cefazolin is a first-generation cephalosporin with a short half-life; requires dose adjustment in renal impairment. Watch for cross-allergenicity in penicillin-allergic patients (approx. 10% risk). Administer parenterally only; no oral formulation available. Common surgical prophylaxis antibiotic due to good coverage of skin flora.
AVYCAZ (ceftazidime-avibactam) is a beta-lactam/beta-lactamase inhibitor combination active against ESBLs, KPC, and OXA-48 carbapenemases. It is not active against metallo-beta-lactamases (e.g., NDM, VIM). Dose adjustment required for creatinine clearance <50 m L/min. Monitor for hypersensitivity reactions, including anaphylaxis. Can cause positive direct Coombs test without hemolysis.
This medication is given by injection or IV, not by mouth.,Report any signs of allergic reaction: rash, hives, itching, difficulty breathing.,May cause diarrhea; notify your doctor if severe or persistent.,Avoid alcohol while taking this medication to prevent disulfiram-like reaction.,Complete the full course as prescribed even if you feel better.
Take exactly as prescribed; complete full course even if feeling better.,Inform your doctor if you have kidney disease; blood tests may be needed to adjust dose.,Report any signs of allergic reaction (rash, hives, difficulty breathing, swelling).,May cause diarrhea; tell your doctor if severe or persistent.,Avoid alcohol during treatment and for 72 hours after last dose due to possible disulfiram-like reaction.
"Phenprocoumon may increase the anticoagulant activities of Cefazolin."
"Warfarin may increase the anticoagulant activities of Cefazolin."
"The protein binding of Cefazolin can be decreased when combined with Phenytoin."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about Cefazolin vs AVYCAZ, answered by our medical review team.
Cefazolin is a Cephalosporin Antibiotic that works by Cefazolin is a first-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), thereby inhibiting transpeptidation and disrupting peptidoglycan cross-linking. This leads to cell lysis and death primarily in susceptible gram-positive bacteria.. AVYCAZ is a Cephalosporin Antibiotic that works by AVYCAZ is a combination of ceftazidime, a cephalosporin beta-lactam antibiotic, and avibactam, a non-beta-lactam beta-lactamase inhibitor. Ceftazidime inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis. Avibactam protects ceftazidime from degradation by certain beta-lactamases, including Ambler class A, class C, and some class D enzymes.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between Cefazolin and AVYCAZ depend on the specific clinical indication. These are both Cephalosporin Antibiotic agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of Cefazolin is: 1-2 g IV/IM every 6-8 hours; maximum 12 g/day.. The standard adult dose of AVYCAZ is: 1 vial (ceftazidime 2g and avibactam 0.5g) IV over 2 hours every 8 hours.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between Cefazolin and AVYCAZ in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. Cefazolin is classified as Category A/B. Cefazolin is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, and adequate, well-controlled studies in pregnant women are lacking. Generally. AVYCAZ is classified as Category C. AVYCAZ (ceftazidime-avibactam) is classified as FDA Pregnancy Category B. Animal reproduction studies in rats and rabbits at doses up to 1.6 times the human dose revealed no eviden. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.