Cefaclor  (PDF Version)

Antibiotic Class

Second-Generation Cephalosporin (true 2nd generation cephalosporin)

Antimicrobial Spectrum

Staphylococcus aureus (methicillin susceptible), Coagulase negative Staphylococci, Streptococcus pneumoniae (penicillin susceptible), Streptococcus spp. Haemophilus influenzae, Moraxella catarrhalis, Neisseria meningitides, Neisseria gonorrhoeae

Mechanism of Action

Cephalosporins exert bactericidal activity by interfering with bacterial cell wall synthesis and inhibiting cross-linking of the peptidoglycan. The cephalosporins are also thought to play a role in the activation of bacterical cell autolysins which may contribute to bacterial cell lysis.


Cephalosporins exhibit time-dependent killing (T > MIC)


Dose of 500mg: Cmax: 17.3 mcg/L; Tmax: 0.7 hours; Half-life: 0.6 hours; Table 10

Adverse Effects

Hypersensitivity: Maculopapular rash, Urticaria, Pruritis, Anaphylaxis/angioedema, eosinophilia

Hematologic: Neutropenia, Leukopenia, Thrombocytopenia

GI: Diarrhea, C. difficile disease

Renal: Interstitial nephritis

Table 14


PO: 250mg, 500mg capsules

       Powder for Suspension: 125mg/5mL, 187mg/5mL, 250 mg/5mL, 375mg/5mL

       Chewable tablets: 125mg, 187mg, 250mg, 375mg

       Extended release tablets: 375mg, 500mg

Dosing in adults

Acute exacerbation of chronic bronchitis: 500 mg extendedrelease tablets PO q12h x 7 days

Acute otitis media: 250mg to 500mg tablets PO q8h

Lower respiratory tract infection: 250mg to 500mg tablets PO q8h

Urinary tract infection: 250mg to 500mg tablets PO q8h

Dosing in pediatrics

20-40mg/kg divided PO q8h

Disease state based dosing

Renal failure:  Caution with markedly impaired renal function; dose adjustment for moderate to severe renal impairment not usually recommended

Hepatic failure:  No dosing changes recommended at this time.


Precautions:  Hypersensitivity to penicillins, renal impairment

Drug Interactions

Live Typhoid Vaccine: decreased immunological response to the typhoid vaccine


Category B: No evidence of risk in humans but studies inadequate.

Monitoring Requirements

Therapeutic:  Culture and sensitivities, serum levels, signs and symptoms of infection, white blood cell count

Toxic:  Urinalysis, BUN, SCr, AST and ALT, skin rash, Neutropenia and leukopenia, Prothrombin time in patients with renal or hepatic impairment or poor nutritional state, as well as patients receiving a protracted course of antimicrobial therapy, and patients previously stabilized on anticoagulant therapy.

Brand names/Manufacturer 

Ceclor“/Eli Lilly; Ceclor CD“/Dura Pharmaceuticals; Cefaclor Extended Release“/Ivax Pharmaceuticals