Cefazolin Cannot Be Given Orally (PO)
Cefazolin is only available for intravenous (IV) or intramuscular (IM) administration and cannot be given orally due to poor oral bioavailability. 1
Why Cefazolin Cannot Be Given Orally
Cefazolin is a first-generation cephalosporin antibiotic that is widely used in clinical practice, but it has specific administration limitations:
- Poor oral absorption: Cefazolin has very poor intestinal absorption when administered orally, which prevents it from reaching therapeutic blood levels 2
- Chemical structure: Like many parenteral cephalosporins, cefazolin's chemical structure makes it unsuitable for oral administration
- Administration routes: All clinical guidelines consistently list cefazolin as an IV or IM medication only 1
Available Routes of Administration for Cefazolin
Cefazolin can only be administered through the following routes:
- Intravenous (IV): The most common route, typically dosed at 1-2g every 8 hours 1
- Intramuscular (IM): Alternative route when IV access is unavailable 3
- Subcutaneous (SC): Emerging alternative route with 74.8% bioavailability compared to IV administration 4
Oral Alternatives to Cefazolin
When an oral first-generation cephalosporin is needed, the following alternatives should be used:
- Cephalexin: The oral first-generation cephalosporin of choice (500 mg 3-4 times daily) 1
- Cefadroxil: Alternative oral first-generation cephalosporin (500 mg twice daily) 1
- Cephradine: Another oral alternative (500 mg 4 times daily) 1
Clinical Implications
This administration limitation has important clinical implications:
- Outpatient therapy: When transitioning from IV to oral therapy, cefazolin must be switched to an appropriate oral alternative
- Surgical prophylaxis: For procedures requiring first-generation cephalosporin prophylaxis, oral cephalexin can be used when IV cefazolin is not feasible 1
- Medication errors: Prescribing cefazolin orally represents a medication error that should be intercepted
Common Pitfalls to Avoid
- Confusion with cephalexin: Don't confuse cefazolin (IV/IM only) with cephalexin (oral only)
- Inappropriate prescribing: Never prescribe cefazolin as an oral medication
- Bioavailability assumptions: Don't assume all cephalosporins have similar routes of administration - they vary significantly
In summary, cefazolin is strictly a parenteral antibiotic that cannot be administered orally. When an oral first-generation cephalosporin is needed, cephalexin is the appropriate alternative.