What is the dose of Cefazolin (Cefazoline), also known as Ancef (Cefazolin), an antibiotic?

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Last updated: May 21, 2025View editorial policy

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From the Guidelines

Cefazolin should be dosed at 1-2 grams intravenously every 8 hours for most adult infections, with adjustments needed for renal impairment, as recommended by the most recent and highest quality study 1.

Key Points

  • The dose of cefazolin can be adjusted based on the patient's renal function and the severity of the infection.
  • For surgical prophylaxis, a single 2-gram dose (3 grams for patients weighing >120 kg) is commonly administered 30-60 minutes before incision.
  • In children, the usual dose is 25-100 mg/kg/day divided into three or four doses.
  • Common brand names for cefazolin include Ancef and Kefzol, though it's frequently dispensed as a generic medication.

Mechanism of Action and Spectrum of Activity

  • Cefazolin works by inhibiting bacterial cell wall synthesis and is particularly effective against gram-positive organisms including Staphylococcus aureus (including methicillin-sensitive strains) and many streptococci.
  • It also has activity against some gram-negative bacteria.

Administration and Storage

  • The medication requires reconstitution before administration and should be stored according to manufacturer guidelines.
  • Patients should be monitored for hypersensitivity reactions, especially those with known penicillin allergies due to potential cross-reactivity.

Evidence-Based Recommendations

  • The recommended dose of cefazolin is supported by the most recent and highest quality study 1, which provides guidelines for the diagnosis and management of complicated intra-abdominal infection in adults and children.
  • Other studies, such as 1, 1, and 1, provide additional guidance on the use of cefazolin in various clinical contexts, but the most recent and highest quality study 1 takes precedence in guiding clinical practice.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Usual Adult Dosage In rare instances, doses of up to 12 grams of cefazolin per day have been used Type of InfectionDoseFrequency Moderate to severe infections 500 mg to 1 gram every 6 to 8 hours Mild infections caused by susceptible gram-positive cocci 250 mg to 500 mg every 8 hours Acute, uncomplicated urinary tract infections 1 gram every 12 hours Pneumococcal pneumonia 500 mg every 12 hours Severe, life-threatening infections (e.g., endocarditis, septicemia) 1 gram to 1. 5 grams every 6 hours

The dose of Cefazolin is 500 mg to 1 gram every 6 to 8 hours for moderate to severe infections. The brand name is not specified in the provided drug label. 2

From the Research

Cefazoline Dose and Brand Name

There is no information available in the provided studies regarding the dose and brand name of Cefazoline.

Relevant Information

  • The studies provided focus on the comparison of nephrotoxicity associated with vancomycin in combination with different antibiotics, such as piperacillin/tazobactam, cefepime, or meropenem 3, 4, 5, 6, 7.
  • The results of these studies suggest that the combination of vancomycin with piperacillin/tazobactam may be associated with a higher risk of acute kidney injury compared to other combinations 3, 4, 5, 7.
  • However, one study found no difference in the trajectory of acute kidney injury between patients receiving vancomycin/piperacillin-tazobactam and those receiving vancomycin/cefepime 6.

Key Findings

  • The incidence of acute kidney injury was higher in patients receiving vancomycin/piperacillin-tazobactam compared to those receiving vancomycin/cefepime or vancomycin/meropenem in some studies 3, 4, 5, 7.
  • The combination of vancomycin with piperacillin/tazobactam was independently associated with an increased risk of acute kidney injury in adult ICU patients 7.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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