Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
Cefazolin vs ANSPOR
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.
Cephalexin is a first-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.
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)
FDA-approved: Treatment of respiratory tract infections, otitis media, skin and skin structure infections, bone infections, genitourinary tract infections caused by susceptible bacteria.,Off-label: Prosthetic joint infections, dental infections, endocarditis prophylaxis.
1-2 g IV/IM every 6-8 hours; maximum 12 g/day.
250-500 mg orally every 6 hours for 10-14 days; maximum 4 g/day.
1.8 hours in normal renal function; extends to 30–70 hours in end-stage renal disease (Cr Cl <10 m L/min).
1.5–2 hours in adults with normal renal function; prolonged to 20–30 hours in severe renal impairment (Cr Cl <10 m L/min)
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.
Cephalexin is not extensively metabolized; it is primarily excreted unchanged in the urine. Minor hepatic metabolism may occur.
Renal: 80–90% unchanged via glomerular filtration and tubular secretion; biliary: <1%; fecal: negligible.
Primarily renal (90–95%) as unchanged drug via glomerular filtration and tubular secretion; biliary excretion negligible (<1%)
80% bound to albumin.
10–20% bound to serum albumin
0.12–0.14 L/kg; approximates extracellular fluid volume, indicating low tissue penetration.
0.13–0.22 L/kg; indicates distribution primarily into extracellular fluid
Intramuscular: 100% (complete absorption).
Oral: 75–90% (well absorbed); IM: 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 10-50 m L/min: 250 mg every 12-24 hours. Cr Cl <10 m L/min: 250 mg every 24-48 hours.
No dosage adjustment required for hepatic impairment.
No specific adjustment recommended; monitor for adverse effects in severe impairment.
50-100 mg/kg/day IV/IM divided every 8 hours; severe infections: 100 mg/kg/day divided every 6-8 hours.
12.5-25 mg/kg orally every 6 hours; maximum 50 mg/kg/day.
No specific adjustment based solely on age; dose adjustment based on renal function per Cr Cl.
Start at lower end of dosing range; monitor renal function and adjust based on Cr Cl.
No FDA black box warning.
No FDA boxed warning exists for cephalexin.
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 reactions including anaphylaxis.,Clostridioides difficile-associated diarrhea (CDAD).,Dosage adjustment required in renal impairment.,Seizures with high doses or renal failure.,Potential for superinfection with prolonged use.
Known hypersensitivity to cefazolin or any cephalosporin antibiotic,Immediate-type hypersensitivity reaction to penicillins (relative caution due to potential cross-allergenicity)
Known hypersensitivity to cephalosporins or penicillins (cross-sensitivity).,Previous immediate hypersensitivity reaction to penicillins.
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).
Iron-fortified infant formula and iron supplements may reduce absorption; take at least 2 hours apart. No other significant food interactions. Avoid alcohol.
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.
Cefradine (ANSPOR) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, and adequate well-controlled studies in pregnant women are lacking. No evidence of teratogenicity; however, caution is advised. First trimester: no known risk; second and third trimesters: no known fetal adverse effects.
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.
Cefradine is excreted into human breast milk in low concentrations. M/P ratio is approximately 0.12–0.20. Considered compatible with breastfeeding by the American Academy of Pediatrics; however, monitor infant for potential diarrhea or allergic reaction.
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.
Increased renal clearance during pregnancy may lower serum concentrations of cefradine. Standard dosing (250–500 mg every 6 hours) is generally adequate; however, for severe infections, consider higher doses or more frequent administration based on clinical response. No specific dose adjustment is routinely recommended, but monitoring therapeutic efficacy is advised.
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.
ANSPOR (cefdinir) is a third-generation oral cephalosporin with activity against Gram-positive and Gram-negative bacteria. It is stable in the presence of some beta-lactamases. Dose adjustment required for Cr Cl <30 m L/min. Avoid use in patients with immediate hypersensitivity to penicillins due to cross-reactivity (approx 10%). Administer with iron supplements or iron-fortified infant formula at least 2 hours apart to reduce chelation. Suspension should be refrigerated and discarded after 10 days.
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, even if you feel better.,Complete the full course of therapy.,If using suspension, shake well before each dose. Refrigerate and discard after 10 days.,Avoid alcohol while taking this medication.,Notify your doctor if you experience diarrhea, rash, or signs of allergic reaction.,Take iron supplements or iron-fortified infant formula at least 2 hours apart from ANSPOR.
"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 ANSPOR, 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.. ANSPOR is a Cephalosporin Antibiotic that works by Cephalexin is a first-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between Cefazolin and ANSPOR 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 ANSPOR is: 250-500 mg orally every 6 hours for 10-14 days; maximum 4 g/day.. 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 ANSPOR 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. ANSPOR is classified as Category C. Cefradine (ANSPOR) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, and adequate well-controlled studies in pregnant women are lacking. N. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.