Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CEFZIL vs ANSPOR
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.
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.
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)
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.
500 mg orally twice daily for 10 days; for uncomplicated skin infections, 250 mg twice daily or 500 mg once daily.
250-500 mg orally every 6 hours for 10-14 days; maximum 4 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; prolonged to 20–30 hours in severe renal impairment (Cr Cl <10 m L/min)
Cefprozil is not extensively metabolized; approximately 60% of the dose is excreted unchanged in the urine. Renal excretion via tubular secretion and glomerular filtration.
Cephalexin is not extensively metabolized; it is primarily excreted unchanged in the urine. Minor hepatic metabolism may occur.
Renal: 80-91% unchanged in urine; biliary/fecal: minimal (<5%)
Primarily renal (90–95%) as unchanged drug via glomerular filtration and tubular secretion; biliary excretion negligible (<1%)
65-80% bound to plasma proteins (mainly albumin)
10–20% bound to serum albumin
0.23-0.35 L/kg; distributes well into body fluids and tissues including skin, soft tissue, and respiratory tract
0.13–0.22 L/kg; indicates distribution primarily into extracellular fluid
Oral: 90-95%
Oral: 75–90% (well absorbed); IM: 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 10-50 m L/min: 250 mg every 12-24 hours. Cr Cl <10 m L/min: 250 mg every 24-48 hours.
No dose adjustment required for mild to moderate hepatic impairment; not studied in severe impairment.
No specific adjustment recommended; monitor for adverse effects in severe 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).
12.5-25 mg/kg orally every 6 hours; maximum 50 mg/kg/day.
Adjust dose based on renal function; no specific geriatric dose adjustments other than renal considerations.
Start at lower end of dosing range; monitor renal function and adjust based on Cr Cl.
None.
No FDA boxed warning exists for cephalexin.
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.,Clostridioides difficile-associated diarrhea (CDAD).,Dosage adjustment required in renal impairment.,Seizures with high doses or renal failure.,Potential for superinfection with prolonged use.
Hypersensitivity to cefprozil or other cephalosporins,Immediate-type hypersensitivity to penicillins (cross-reactivity risk)
Known hypersensitivity to cephalosporins or penicillins (cross-sensitivity).,Previous immediate hypersensitivity reaction 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).
Iron-fortified infant formula and iron supplements may reduce absorption; take at least 2 hours apart. No other significant food interactions. Avoid alcohol.
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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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 ANSPOR, 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.. 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 CEFZIL 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 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 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 CEFZIL 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. 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. 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.