Pharmacology

Cefaclor is a second-generation cephalosporin antibiotic. It inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death. It is bactericidal and effective against both Gram-positive and some Gram-negative organisms. Cefaclor monohydrate is a prodrug that, once absorbed, releases the active drug cefaclor.

Indications

Cefaclor is indicated for the treatment of the following infections caused by susceptible microorganisms:

  • Respiratory tract infections (e.g., pharyngitis, tonsillitis, otitis media, bronchitis)

  • Skin and soft tissue infections

  • Urinary tract infections

  • Pneumonia

  • Sinusitis

Dosage & Administration

Adults and children over 10 years (≥40 kg):

  • Typical dose: 250–500 mg every 8 hours

  • Severe infections: Up to 1 g every 8 hours

Children (under 10 years):

  • 20–40 mg/kg/day in divided doses every 8 hours

  • Maximum: 1 g/day

  • For otitis media and pharyngitis: 20 mg/kg/day

  • For more severe infections: 40 mg/kg/day

Note: Dose adjustment may be needed in renal impairment.

Drug Interactions

  • Probenecid: May increase cefaclor levels by decreasing renal excretion.

  • Warfarin & other anticoagulants: May increase bleeding tendency.

  • Live vaccines (e.g., typhoid): Efficacy may be reduced.

  • Antacids: May reduce absorption; administer cefaclor 1 hour before or 2 hours after antacids.

Contraindications

  • Known hypersensitivity to cephalosporins or any component of the formulation.

  • History of severe allergic reaction (e.g., anaphylaxis) to beta-lactam antibiotics.

Side Effects

  • Common: Diarrhea, nausea, vomiting, abdominal pain, rash

  • Less common: Headache, dizziness, candidiasis

  • Serious (rare): Anaphylaxis, Stevens-Johnson syndrome, serum sickness-like reactions, hepatic dysfunction, hematologic abnormalities (e.g., eosinophilia, thrombocytopenia)

Pregnancy & Lactation

  • Pregnancy Category B: No evidence of harm in animal studies; use only if clearly needed.

  • Lactation: Excreted in small amounts in breast milk; use with caution.

Precautions & Warnings

  • Use cautiously in patients with a history of penicillin allergy.

  • Monitor renal function in prolonged therapy or in those with renal impairment.

  • Can cause Clostridioides difficile-associated diarrhea.

  • Long-term use may lead to superinfection with non-susceptible organisms.

Overdose Effects

  • Symptoms may include nausea, vomiting, diarrhea, and abdominal cramps.

  • Neurological symptoms (e.g., seizures) may occur in severe cases, especially in renal impairment.

  • Treatment is symptomatic and supportive; hemodialysis may aid in elimination.

Therapeutic Class

  • Second-generation cephalosporin antibiotics

Storage Conditions

  • Store below 25°C, in a dry place, away from light and moisture.

  • Reconstituted suspension: Store in the refrigerator (2–8°C) and use within 14 days.

Chemical Structure

Molecular Formula: C15H14ClN3O4S
Molecular Weight: 367.81 g/mol

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