Cephalexin

General

• Type: 1st generation cephalosporin
• Dosage forms
  • Tabs: 250mg, 500mg, 750mg
  • Liquid: 125mg/5mL; 250mg/5mL
• Common Trade Names: Keflex

Adult Dosing

General

250-500mg PO q6h

Strep Pharyngitis

500mg PO q12h x 10 days

Uncomplicated UTI

500mg PO q12h x 7-14 days

Cellulitis and Other Skin Infections

500mg PO q12h

Pediatric Dosing

General

• 25-50 mg/kg/day PO divided q6-12h

Otitis Media

• 75-100 mg/kg/day PO divided q12h x 10 days
• Max: 4,000 mg/24h

Community Acquired Pneumonia

• 75-100 mg/kg/day PO divided q12h x 10 days

Mechanism of Action

• Bactericidal
  • Inhibits cell wall

Adverse Drug Reactions

• Caution advised with contraceptives

Kinetics

• Half-life: 1h (~20hr ESRD)
• Metabolism: Minimal
• Excretion: Primarily urine (>90% unchanged)

Pregnancy/Lactation

• Pregnancy = B
• Lactation = Safe

Overdose Management

Max: 4,000 mg/day

See Also

• Cephalosporin Cross-reactivity

Source

• Sanford 2010
• Epocrates