Cefadroxil vs Cephalexin for Streptococcal Infections
Both cefadroxil and cephalexin are equally effective first-generation cephalosporins for treating streptococcal infections in penicillin-allergic patients, with no data showing superiority of one over the other, though cefadroxil offers the advantage of once-daily dosing which may enhance compliance. 1
Comparative Efficacy
Clinical Evidence
- No superiority demonstrated: The American Heart Association explicitly states that no data show superiority of one oral cephalosporin over another for prevention or treatment of streptococcal infections 2
- Both agents achieve comparable bacteriologic eradication rates of approximately 92-93% in streptococcal pharyngitis 3, 4
- Clinical failure rates are similarly low for both drugs, with studies showing 3-7% failure rates for cephalexin and approximately 8% for cefadroxil when compared to penicillin 5, 3
Dosing Regimens
- Cefadroxil: 30 mg/kg once daily (maximum 1 gram) for 10 days 1
- Cephalexin: 20 mg/kg per dose twice daily (maximum 500 mg/dose) for 10 days 1
Key Advantages and Considerations
Cefadroxil Benefits
- Once-daily dosing significantly improves compliance compared to multiple daily doses, with compliance rates exceeding 90% in pediatric studies 3
- Animal model data suggest superior lung tissue penetration and bactericidal activity (8-fold more effective than cephalexin in reducing viable streptococci), though clinical significance in pharyngitis is unclear 6
Cephalexin Benefits
- Generic availability and lower cost make cephalexin widely accessible and relatively inexpensive 2
- Extensive clinical experience spanning over 12 years with cure rates consistently 90% or higher 7
- Proven efficacy in twice-daily dosing regimens that enhance medication compliance compared to four-times-daily regimens 4
Critical Safety Considerations
Cross-Reactivity Warning
- Both agents must be avoided in patients with immediate/anaphylactic penicillin reactions due to up to 10% cross-reactivity risk with first-generation cephalosporins 2, 1
- Only use in patients with non-immediate (non-anaphylactic) penicillin allergies 1
Alternative Agents for Immediate Allergy
- For immediate/anaphylactic penicillin reactions, use clindamycin (7 mg/kg three times daily for 10 days) or azithromycin (12 mg/kg once daily for 5 days) instead 1
- Clindamycin has approximately 1% resistance rate in the United States, making it highly reliable 1
Treatment Duration Requirements
- Full 10-day course is mandatory for both cefadroxil and cephalexin to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever 1
- Shortening the course by even a few days results in appreciable increases in treatment failure rates 1
Common Pitfalls to Avoid
- Do not assume cefadroxil is superior based on once-daily dosing alone - efficacy is equivalent, and the choice should be based on cost, availability, and patient preference for dosing frequency 2
- Do not prescribe shorter courses than 10 days for either agent, as this leads to treatment failure and potential complications 1
- Do not use either agent in patients with documented immediate hypersensitivity to penicillin - the 10% cross-reactivity risk is clinically significant 1