Is the Vancomycin dosage appropriate?

From the Guidelines

Vancomycin dosing should be based on actual body weight, with a recommended dose of 15-20 mg/kg every 8-12 hours, not to exceed 2 g per dose, and trough concentrations should be monitored to achieve target levels of 15-20 mcg/mL for serious MRSA infections. The Infectious Diseases Society of America recommends vancomycin dosing based on actual body weight, with adjustments for renal function and other factors 1. For patients with normal kidney function, vancomycin dosing typically ranges from 15-20 mg/kg every 8-12 hours, with a goal of achieving trough concentrations of 10-20 mcg/mL depending on the infection type 1.

Some key points to consider when determining vancomycin dosage include:

• Weight-based dosing is particularly important in obese patients, who are likely to be underdosed when conventional dosing strategies are used 1
• Trough vancomycin monitoring is recommended for serious infections and patients who are morbidly obese, have renal dysfunction, or have fluctuating volumes of distribution 1
• Vancomycin trough concentrations <10 mcg/mL have been associated with increased risk of treatment failure, while concentrations >20 mcg/mL may increase the risk of nephrotoxicity 1
• The pharmacodynamic parameter that best predicts efficacy of vancomycin is the ratio of the area under the curve (AUC) to the MIC (AUC/MIC), with a target AUC/MIC >400 1

For accurate dosing recommendations, specific patient details are necessary, including weight, creatinine clearance, infection site, and organism sensitivity. Therapeutic drug monitoring is essential to ensure effective treatment while avoiding toxicity, and common side effects such as nephrotoxicity and ototoxicity can be minimized with appropriate dosing and monitoring 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Infusion-related events are related to both the concentration and the rate of administration of vancomycin. Concentrations of no more than 5 mg/mL and rates of no more than 10 mg/min, are recommended in adults Patients with Normal Renal Function Adults The usual daily intravenous dose is 2 g divided either as 500 mg every 6 hours or 1 g every 12 hours. Each dose should be administered at no more than 10 mg/min or over a period of at least 60 minutes, whichever is longer.

The appropriateness of the Vancomycin dosage cannot be determined without knowing the specific patient's characteristics, such as their renal function, age, and weight. According to the drug label, dosage adjustment must be made in patients with impaired renal function 2. The label also provides a dosage table for patients with impaired renal function 2, but this requires knowledge of the patient's creatinine clearance. Without this information, it is not possible to determine if the Vancomycin dosage is appropriate.

From the Research

Vancomycin Dosage Appropriateness

The appropriateness of vancomycin dosage can be evaluated based on several studies that have investigated the relationship between vancomycin trough concentrations and clinical outcomes.

• A study published in 2009 3 found that a vancomycin regimen of 1 g i.v. every 12 hours in critically ill trauma patients with MRSA pneumonia and normal renal function is unlikely to achieve trough concentrations of 15 to 20 mg/L, suggesting that higher doses may be needed.
• Another study published in 2010 4 found that higher vancomycin trough concentrations were associated with increased risk of nephrotoxicity, but did not significantly improve clinical outcomes.
• A review published in 2018 5 critically evaluated the current practice of vancomycin dosing and monitoring, and proposed two user-friendly and scientifically based dosing strategies to improve the efficiency of vancomycin dosing while avoiding the risk of nephrotoxicity.
• A study published in 2014 6 found that the standard one gram dose of vancomycin is not adequate prophylaxis for MRSA, and that weight-based dosing is necessary to achieve adequate vancomycin levels.
• A prospective cohort study published in 2006 7 found that high-dose vancomycin therapy was effective in treating MRSA infections, but was associated with increased risk of nephrotoxicity, particularly in patients with high vancomycin MIC.

Key Findings

• Vancomycin trough concentrations of 15 to 20 mg/L are generally considered adequate for treating MRSA infections 3, 7.
• Higher vancomycin doses may be needed to achieve adequate trough concentrations in critically ill patients 3 and obese patients 6.
• Weight-based dosing is necessary to achieve adequate vancomycin levels 6.
• Higher vancomycin trough concentrations are associated with increased risk of nephrotoxicity 4, 7.
• Alternative dosing strategies, such as continuous infusion and AUC-based dosing, may be necessary to optimize vancomycin therapy 5.