Cefazolin Has No Oral Formulation
Cefazolin is only available for intravenous (IV) or intramuscular (IM) administration—there is no oral formulation of this antibiotic. 1, 2, 3, 4
Why Cefazolin Cannot Be Given Orally
- Cefazolin is a parenteral-only cephalosporin antibiotic that must be administered IV or IM due to poor oral bioavailability 4, 5
- All guideline-recommended dosing for cefazolin specifies IV or IM routes exclusively, with no oral option mentioned in any clinical protocol 1, 2
- Recent research on subcutaneous cefazolin administration (showing 74.8% bioavailability) still requires injection—oral administration was not studied because it is not viable 3
Oral Alternatives to Cefazolin
If you need an oral first-generation cephalosporin with similar antimicrobial coverage, cephalexin is the appropriate choice. 6, 7, 8, 9
Cephalexin Dosing (Oral Equivalent)
- Adults: 500 mg orally four times daily (every 6 hours) for most infections 7, 8, 9
- Pediatric: 75-100 mg/kg/day divided into 3-4 doses for serious infections like MSSA; 25-50 mg/kg/day in 4 divided doses for mild-moderate infections 7
- Duration: Typically 7-10 days depending on clinical response 7
Clinical Evidence Supporting Cephalexin as Oral Alternative
- A randomized controlled trial demonstrated that oral cephalexin 500 mg four times daily was non-inferior to IV cefazolin 2g daily (with probenecid) for uncomplicated mild-moderate skin and soft tissue infections, with failure rates of 4.2% vs 6.1% respectively 9
- Cephalexin achieves cure rates of 90% or higher for streptococcal and staphylococcal skin and soft tissue infections 6
- For urinary tract infections, cephalexin 500 mg twice or thrice daily provides comparable efficacy to traditional first-line agents against non-ESBL Enterobacteriaceae 8
Important Limitations of Cephalexin
- Do not use in patients with history of anaphylaxis, angioedema, or urticaria to penicillins due to cross-reactivity risk 6, 7
- Ineffective against: MRSA, Pseudomonas aeruginosa, beta-lactamase-producing Moraxella catarrhalis, and has poor activity against Haemophilus influenzae 7
- Not appropriate for: Severe infections requiring broad gram-negative coverage, acute bacterial sinusitis, or infections where MRSA is suspected 6, 7
- High resistance rates (96%) among viridans group streptococci limit its use for endocarditis prophylaxis 7