Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CEFACLOR vs ANCEF
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Bactericidal; inhibits cell wall synthesis by binding to penicillin-binding proteins (PBPs), disrupting peptidoglycan cross-linking.
First-generation cephalosporin that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), disrupting peptidoglycan cross-linking.
Acute otitis media,Acute exacerbations of chronic bronchitis,Pharyngitis/tonsillitis,Uncomplicated skin and skin structure infections,Urinary tract infections,Lower respiratory tract infections including pneumonia
Respiratory tract infections,Urinary tract infections,Skin and skin structure infections,Biliary tract infections,Bone and joint infections,Genital infections,Septicemia,Endocarditis,Perioperative prophylaxis
250-500 mg orally every 8 hours
1-2 g IV/IM every 8 hours; maximum 6 g/day.
Terminal elimination half-life: 0.5-1 hour; prolonged to 2-3 hours in renal impairment
1.5-2 hours in adults with normal renal function; prolongs significantly in renal impairment (up to 30 hours in anuria).
Hepatic (minor); primarily renally excreted unchanged.
Not significantly metabolized; primarily excreted unchanged by renal tubular secretion.
Renal: 60-85% unchanged in urine within 8 hours; biliary/fecal: minor, ~5%
Primarily renal (80-90% unchanged by glomerular filtration and tubular secretion); small amounts biliary (<1%) and fecal.
25-50% bound to plasma proteins, primarily albumin
80-85% bound to serum albumin.
0.35-0.5 L/kg; distributes into most body tissues and fluids, including middle ear, sinus, and respiratory secretions
0.14-0.17 L/kg; primarily extracellular fluid.
Oral: 95% well absorbed; food does not significantly affect absorption
IM: ~100% (well absorbed); IV: 100%.
Cr Cl 10-50 m L/min: 50% of usual dose every 8 hours; Cr Cl <10 m L/min: 50% of usual dose every 12 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 adjustment required for mild to moderate hepatic impairment; safety in severe impairment not established
No adjustment required for hepatic impairment.
20-40 mg/kg/day orally divided every 8 hours; maximum 1 g/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.
No specific adjustment, but monitor renal function; initiate at lower end of dosing range due to age-related renal decline
No specific adjustment; use renal function-based dosing as per renal_adjustment.
None.
No FDA boxed warnings.
Hypersensitivity reactions, including anaphylaxis,Clostridium difficile-associated diarrhea,Seizures (especially with renal impairment),Prolonged PT in patients on anticoagulants,False-positive urine glucose test
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
Known hypersensitivity to cephalosporins or any component,Previous immediate hypersensitivity reaction to penicillins (cross-sensitivity)
Hypersensitivity to cefazolin or other cephalosporins,History of severe immediate hypersensitivity reaction (e.g., anaphylaxis) to penicillins
No significant food interactions; cefaclor can be taken with or without food.,Absorption may be slightly delayed with food but total bioavailability is unaffected.,Avoid grapefruit juice? No known interaction.,Alcohol: No specific interaction, but caution as it may increase side effects like gastrointestinal upset.
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).
First trimester: No increased risk of major congenital malformations based on limited human data; animal studies show no teratogenicity at clinically relevant doses. Second/third trimester: No known fetal risks; Cefaclor crosses the placenta with fetal serum concentrations approximately 10-20% of maternal levels.
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.
Cefaclor is excreted into human breast milk in low concentrations (M/P ratio approximately 0.05-0.10). Considered compatible with breastfeeding by the American Academy of Pediatrics; use with caution in nursing infants with potential for diarrhea or allergic sensitization.
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 required in pregnancy; pharmacokinetic changes (increased volume of distribution, renal clearance) do not necessitate dose modification due to wide therapeutic index.
No dosage adjustment recommended for pregnancy. Increased clearance in pregnancy may necessitate higher doses in severe infections, but standard dosing is typically effective.
Cefaclor is a second-generation cephalosporin with activity against both Gram-positive and Gram-negative organisms, but not Pseudomonas or MRSA.,It is stable against some beta-lactamases, but resistance can occur via extended-spectrum beta-lactamases (ESBLs).,Dose adjustment is required in renal impairment (Cr Cl <40 m L/min).,It is available as an oral suspension and capsules; suspension must be refrigerated and shaken well before use.,Cefaclor may cause a serum sickness-like reaction, especially in children, characterized by rash, arthralgia, and fever.,It has a short half-life (0.6-0.9 hours) and is usually dosed every 8 hours.,Avoid use in patients with immediate hypersensitivity to penicillins due to cross-reactivity risk (about 10%).
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, usually every 8 hours, with or without food.,Complete the full course of therapy even if you feel better to prevent bacterial resistance.,Shake the oral suspension well before each dose and refrigerate it; discard any unused portion after 14 days.,Contact your healthcare provider if you develop severe diarrhea, rash, joint pain, or fever.,Inform your doctor if you have a history of allergic reactions to penicillins or cephalosporins.,Do not take this medication if you are allergic to cefaclor or any other cephalosporin antibiotic.,If a dose is missed, take it as soon as remembered unless it is almost time for the next dose; do not double the dose.
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).
"Phenindione, a vitamin K antagonist anticoagulant, potentiates the effect of cefaclor, a second-generation cephalosporin antibiotic. Cefaclor may reduce vitamin K production by suppressing intestinal flora, thereby enhancing the anticoagulant effect of phenindione. This interaction can lead to an increased international normalized ratio (INR) and risk of bleeding, particularly in patients with poor nutritional status or prolonged antibiotic therapy."
"Dicoumarol may increase the anticoagulant activities of Cefaclor."
"Warfarin may increase the anticoagulant activities of Cefaclor."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about CEFACLOR vs ANCEF, answered by our medical review team.
CEFACLOR is a Cephalosporin Antibiotic that works by Bactericidal; inhibits cell wall synthesis by binding to penicillin-binding proteins (PBPs), disrupting 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 CEFACLOR 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 CEFACLOR is: 250-500 mg orally every 8 hours. 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 CEFACLOR 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. CEFACLOR is classified as Category A/B. First trimester: No increased risk of major congenital malformations based on limited human data; animal studies show no teratogenicity at clinically relevant doses. Second/third t. 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.