How do you prescribe cephazolin?

Cefazolin Prescription Guidelines

Cefazolin should be dosed according to the FDA-approved regimen of 500 mg to 1 gram every 6 to 8 hours for moderate to severe infections, with mandatory dose adjustments for patients with reduced renal function. 1

Dosing Regimens by Indication

Adult Dosing

• Moderate to severe infections: 500 mg to 1 gram IV every 6 to 8 hours
• Mild infections (gram-positive cocci): 250 mg to 500 mg IV every 8 hours
• Acute uncomplicated UTIs: 1 gram IV every 12 hours
• Pneumococcal pneumonia: 500 mg IV every 12 hours
• Severe, life-threatening infections: 1 gram to 1.5 grams IV every 6 hours 1

Perioperative Prophylaxis

• 1 gram IV administered 30-60 minutes before surgery
• For lengthy procedures (≥2 hours): Additional 500 mg to 1 gram IV during surgery
• Postoperatively: 500 mg to 1 gram IV every 6-8 hours for 24 hours
• For high-risk surgeries (e.g., open-heart, prosthetic arthroplasty): May continue for 3-5 days 1

Renal Dosage Adjustments (Critical)

Renal adjustment is mandatory to prevent neurotoxicity and seizures 2:

• CrCl ≥55 mL/min or SCr ≤1.5 mg/dL: Standard dosing
• CrCl 35-54 mL/min or SCr 1.6-3.0 mg/dL: Standard dose at minimum 8-hour intervals
• CrCl 11-34 mL/min or SCr 3.1-4.5 mg/dL: 1/2 standard dose every 12 hours
• CrCl ≤10 mL/min or SCr ≥4.6 mg/dL: 1/2 standard dose every 18-24 hours 1

Always administer an initial loading dose appropriate to infection severity, regardless of renal function.

Pediatric Dosing

• General infections: 25-50 mg/kg/day divided into 3-4 equal doses
• Severe infections: Up to 100 mg/kg/day
• Not recommended for premature infants and neonates 1

Pediatric Renal Adjustments

• CrCl 70-40 mL/min: 60% of normal daily dose every 12 hours
• CrCl 40-20 mL/min: 25% of normal daily dose every 12 hours
• CrCl 20-5 mL/min: 10% of normal daily dose every 24 hours 1

Administration Methods

Intramuscular

• Reconstitute with Sterile Water for Injection
• For 500 mg vial: Add 2 mL (yields 225 mg/mL)
• For 1 g vial: Add 2.5 mL (yields 330 mg/mL)
• Inject into large muscle mass 1

Intravenous

• Direct (bolus): Dilute with approximately 5 mL Sterile Water for Injection and inject slowly over 3-5 minutes
• Intermittent/continuous infusion: Dilute in 50-100 mL of compatible solution (e.g., NS, D5W) 1

Important Clinical Considerations

Monitoring

• Renal function: Regular monitoring is essential, especially in elderly patients who may have prolonged excretion time even with seemingly normal renal function 3
• Clinical response: Expect improvement within 72 hours; if none, reevaluate treatment plan

Potential Adverse Effects

• Neurotoxicity risk factors: Older age, pre-existing CNS conditions, renal impairment 2
• Warning signs: Mental status changes, seizures (particularly with excessive dosing in renal dysfunction) 2

Efficacy Profile

• Highly effective against gram-positive organisms, particularly Staphylococcus aureus (including penicillin-resistant strains) 4
• Effective against most Enterobacteriaceae except indole-positive Proteus and Enterobacter species 4
• Not effective against Pseudomonas aeruginosa 4

Common Pitfalls to Avoid

1. Failure to adjust for renal function: This is the most dangerous error and can lead to neurotoxicity and seizures 2
2. Inadequate preoperative timing: For surgical prophylaxis, administer 30-60 minutes before incision for optimal tissue levels 1
3. Underestimating elderly patients' risk: Patients over 60 may have prolonged half-life even with seemingly normal renal function 3
4. Inappropriate use for Pseudomonas infections: Cefazolin is ineffective against P. aeruginosa 4

By following these guidelines, cefazolin can be safely and effectively prescribed for appropriate indications while minimizing the risk of adverse effects.