Cephalexin

C. diff Risk

Medium

Oral Bioavailability

Excellent

Approximate Cost

$1/day (Liquid $$$$$$)

Dosing

Usual dose: 500 mg PO q6h

12.5-25 mg/kg/dose q6h
PNA-days 21+

12.5-25 mg/kg/dose q8h
PNA-days 7 - 21

12.5-25 mg/kg/dose q12h
PNA-days 0 - 7

Renally cleared, requires dosage adjustment with changes in renal function. Consult a pharmacist for renal dosing.

General Information

Common Usage

Uncomplicated skin and soft tissue infection, osteomyelitis, MSSA infections

Adverse Effects

  • Allergy/rash (immediate or delayed), cephalexin and amoxicillin have the same side chain, hence cross -allergenicity may occur

  • Can cause positive Coombs, cytopenias, eosinophilia

Oral Liquids

Concentration: 50 mg/mL
Taste: very palatable
Not all strengths of oral liquids are listed nor are available on IWK formulary

Tablet/Capsule Strengths

500 mg tablet
Tablets and capsules are preferred especially over an unpleasant tasting liquid.
Not all strengths of oral tablets/capsules are listed and they are not all available on the IWK formulary.

Pharmacology

Antimicrobial class: First generation cephalosporin - oral

Average serum half life:

  • Neonates: 5 hours.

  • Children 3 to 12 months: 2.5 hours.

  • Adults: 0.5-1.2 hours

Route of Elimination: 80% to 100% of dose excreted as unchanged drug in urine within 8 hours