Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CEFZIL vs ANCEF
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Cefprozil inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting peptidoglycan cross-linking.
First-generation cephalosporin that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), disrupting peptidoglycan cross-linking.
Pharyngitis/tonsillitis (Streptococcus pyogenes),Otitis media (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis),Acute sinusitis,Acute bacterial exacerbation of chronic bronchitis,Skin and skin structure infections (uncomplicated)
Respiratory tract infections,Urinary tract infections,Skin and skin structure infections,Biliary tract infections,Bone and joint infections,Genital infections,Septicemia,Endocarditis,Perioperative prophylaxis
500 mg orally twice daily for 10 days; for uncomplicated skin infections, 250 mg twice daily or 500 mg once daily.
1-2 g IV/IM every 8 hours; maximum 6 g/day.
1.2-1.5 hours in healthy adults; prolonged in renal impairment (e.g., up to 6-8 hours in severe renal failure)
1.5-2 hours in adults with normal renal function; prolongs significantly in renal impairment (up to 30 hours in anuria).
Cefprozil is not extensively metabolized; approximately 60% of the dose is excreted unchanged in the urine. Renal excretion via tubular secretion and glomerular filtration.
Not significantly metabolized; primarily excreted unchanged by renal tubular secretion.
Renal: 80-91% unchanged in urine; biliary/fecal: minimal (<5%)
Primarily renal (80-90% unchanged by glomerular filtration and tubular secretion); small amounts biliary (<1%) and fecal.
65-80% bound to plasma proteins (mainly albumin)
80-85% bound to serum albumin.
0.23-0.35 L/kg; distributes well into body fluids and tissues including skin, soft tissue, and respiratory tract
0.14-0.17 L/kg; primarily extracellular fluid.
Oral: 90-95%
IM: ~100% (well absorbed); IV: 100%.
Cr Cl 30-49 m L/min: 250 mg twice daily; Cr Cl 10-29 m L/min: 250 mg once daily; Cr Cl <10 m L/min: 250 mg every 48 hours.
Cr Cl >55 m L/min: 1-2 g every 8 h. Cr Cl 35-54: 1-2 g every 8-12 h. Cr Cl 11-34: 1-2 g every 12 h. Cr Cl <10: 1-2 g every 24-48 h. Hemodialysis: 1-2 g after dialysis.
No dose adjustment required for mild to moderate hepatic impairment; not studied in severe impairment.
No adjustment required for hepatic impairment.
6 months to 12 years: 30 mg/kg/day divided twice daily (max 1 g/day); for pharyngitis/tonsillitis: 20 mg/kg/day divided twice daily (max 500 mg/day).
Infants and children 1 month and older: 25-50 mg/kg/day IV/IM divided every 8 h; severe infections: 100 mg/kg/day divided every 6-8 h. Maximum 6 g/day.
Adjust dose based on renal function; no specific geriatric dose adjustments other than renal considerations.
No specific adjustment; use renal function-based dosing as per renal_adjustment.
None.
No FDA boxed warnings.
Hypersensitivity reactions (including anaphylaxis) in penicillin-allergic patients,Clostridium difficile-associated diarrhea (CDAD),Seizures with high doses or renal impairment,Hemolytic anemia (rare),Prolonged prothrombin time (rare)
Hypersensitivity reactions, including anaphylaxis, especially in patients with penicillin allergy,Clostridium difficile-associated diarrhea,Renal impairment: dose adjustment required,Prolonged use may result in superinfection,Seizures at high doses in renal impairment
Hypersensitivity to cefprozil or other cephalosporins,Immediate-type hypersensitivity to penicillins (cross-reactivity risk)
Hypersensitivity to cefazolin or other cephalosporins,History of severe immediate hypersensitivity reaction (e.g., anaphylaxis) to penicillins
No clinically significant food interactions. High-fat meals may slightly delay absorption but do not affect overall absorption extent. Avoid alcohol during therapy as it may increase risk of disulfiram-like reaction (rare with cephalosporins).
No significant food interactions. Cefazolin may be administered with or without food. However, alcohol should be avoided due to potential disulfiram-like reaction (cephalosporin side chain effect).
FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies. Risk cannot be ruled out. First trimester: No reported teratogenicity in animal studies; clinical data insufficient. Second/third trimester: No known risk; use only if clearly needed.
No evidence of teratogenicity in animal studies. Crosses placenta. Use only if clearly needed during pregnancy. First trimester: limited data, no known malformations. Second and third trimesters: no known fetal harm.
Cefprozil (CEFZIL) is excreted in human milk in low amounts. Milk-to-plasma ratio is approximately 0.3. Considered compatible with breastfeeding; however, monitor infant for potential gastrointestinal effects.
Excreted in breast milk in low concentrations (M/P ratio unknown, likely low). Considered compatible with breastfeeding due to poor oral bioavailability in infants.
No dose adjustment routinely required. Physiologic changes in pregnancy (increased renal clearance, volume of distribution) may require higher doses for severe infections, but data insufficient to recommend specific adjustments. Use standard adult dosing unless renal impairment.
No dosage adjustment recommended for pregnancy. Increased clearance in pregnancy may necessitate higher doses in severe infections, but standard dosing is typically effective.
CEFZIL (cefprozil) is a second-generation cephalosporin with activity against Gram-positive cocci (including Streptococcus pyogenes, Streptococcus pneumoniae, and methicillin-susceptible Staphylococcus aureus) and some Gram-negative bacteria (Haemophilus influenzae, Moraxella catarrhalis, Escherichia coli). It has a longer half-life (1.3 hours) compared to cephalexin, allowing twice-daily dosing. It is FDA-approved for acute sinusitis, pharyngitis/tonsillitis, otitis media, acute bacterial exacerbation of chronic bronchitis, secondary bacterial infection of acute bronchitis, and uncomplicated skin and skin structure infections. Note that it is not reliable against penicillin-resistant S. pneumoniae or beta-lactamase-producing H. influenzae (though it is more stable than first-generation agents). In penicillin-allergic patients, cross-reactivity risk is low but not zero (avoid if immediate-type hypersensitivity to penicillin). Dose adjustment required for creatinine clearance <30 m L/min: give standard dose every 12 hours for first dose, then 50% of standard dose every 12 hours. Available as 250 mg and 500 mg tablets and as an oral suspension (125 mg/5 m L or 250 mg/5 m L). Refrigerate suspension after reconstitution; discard after 14 days.
Cefazolin (Ancef) is a first-generation cephalosporin with excellent gram-positive coverage, often used for surgical prophylaxis. It has poor CSF penetration, so it is not suitable for meningitis. Cross-allergenicity with penicillins occurs in approximately 10% of patients. Dose adjustment required in renal impairment (Cr Cl <30 m L/min).
Take this medication exactly as prescribed by your doctor, usually every 12 hours.,You may take this medication with or without food; however, taking with food may help reduce stomach upset.,Complete the full course of therapy, even if you feel better, to reduce the risk of antibiotic resistance.,Shake the oral suspension well before each dose. Use a proper measuring spoon or dosing syringe to ensure accurate dose.,Store the oral suspension in the refrigerator (not freezer) and discard any unused portion after 14 days.,Notify your doctor if you develop diarrhea, especially if it is watery or bloody; do not use anti-diarrhea medications without consulting your doctor.,Seek immediate medical attention if you experience signs of an allergic reaction: rash, hives, itching, difficulty breathing, tightness in chest, swelling of face/mouth/tongue.,Inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding.
Take exactly as prescribed, even if you feel better.,Complete the full course to prevent resistance.,Report any signs of allergic reaction (rash, itching, difficulty breathing) immediately.,May cause diarrhea; contact your doctor if severe or persistent.,Avoid alcohol during treatment and for 48 hours after last dose (disulfiram-like reaction possible but rare).
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about CEFZIL vs ANCEF, answered by our medical review team.
CEFZIL is a Cephalosporin Antibiotic that works by Cefprozil inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting peptidoglycan cross-linking.. ANCEF is a Cephalosporin Antibiotic that works by First-generation cephalosporin that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), disrupting peptidoglycan cross-linking.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CEFZIL and ANCEF 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 CEFZIL is: 500 mg orally twice daily for 10 days; for uncomplicated skin infections, 250 mg twice daily or 500 mg once daily.. The standard adult dose of ANCEF is: 1-2 g IV/IM every 8 hours; maximum 6 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 CEFZIL and ANCEF 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. CEFZIL is classified as Category C. FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies. Risk cannot be ruled out. First trimester: No reported teratogenicity in a. ANCEF is classified as Category C. No evidence of teratogenicity in animal studies. Crosses placenta. Use only if clearly needed during pregnancy. First trimester: limited data, no known malformations. Second and th. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.