What is the vancomycin dose for a 108kg obese individual with sepsis?

From the Guidelines

For an obese individual weighing 108kg with sepsis, the recommended vancomycin dosing is 25-30 mg/kg actual body weight as a loading dose, followed by 15-20mg/kg actual body weight every 8-12 hours, typically resulting in a dose of 2.7-3.2g as a loading dose, and 1.6-2.2g every 8-12 hours thereafter.

Key Considerations

• The initial loading dose is crucial to rapidly achieve target trough concentrations, especially in sepsis cases where timely effective treatment is vital 1.
• Vancomycin dosing requires therapeutic drug monitoring, with target trough concentrations of 15-20 mg/L for serious infections like sepsis 2, 3, 4, 5.
• The first trough level should be measured before the fourth dose, drawn 30 minutes before administration, to guide dosing adjustments based on the patient's renal function and trough levels.
• Vancomycin is primarily eliminated by the kidneys, so renal function assessment is essential before starting therapy, and adequate hydration should be maintained during treatment to minimize the risk of nephrotoxicity.
• For obese patients, using actual body weight with close monitoring is a common approach, although adjusted body weight calculations may also be considered.
• Concurrent nephrotoxic medications should be used cautiously to avoid enhancing the risk of nephrotoxicity.

Rationale

The rationale behind using a loading dose followed by weight-based dosing is to ensure that therapeutic levels are achieved quickly and maintained, given the expanded volume of distribution in septic patients and the importance of achieving adequate drug concentrations for effective treatment of serious infections like sepsis 1. The recommendation for trough concentrations of 15-20 mg/L is based on evidence that these levels are associated with improved clinical outcomes in serious MRSA infections, including sepsis 2, 3, 4, 5.

Monitoring and Adjustments

• Therapeutic Drug Monitoring (TDM): Essential for adjusting vancomycin doses to achieve target trough concentrations, especially in patients with renal dysfunction, obesity, or fluctuating volumes of distribution.
• Renal Function Assessment: Critical before initiating therapy and during treatment to adjust doses appropriately and minimize nephrotoxicity risk.
• Hydration and Nephrotoxic Medications: Adequate hydration is recommended, and caution should be exercised with concurrent nephrotoxic medications to prevent enhanced nephrotoxicity risk.

By following these guidelines and considering the patient's specific clinical context, healthcare providers can optimize vancomycin therapy for obese individuals with sepsis, aiming to improve outcomes by achieving appropriate drug concentrations while minimizing potential adverse effects.

From the FDA Drug Label

Other patient factors, such as age or obesity, may call for modification of the usual intravenous daily dose The usual daily intravenous dose is 2 g divided either as 500 mg every 6 hours or 1 g every 12 hours. In selected patients in need of fluid restriction, a concentration up to 10 mg/mL may be used; use of such higher concentrations may increase the risk of infusion-related events. 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.

The vancomycin dose for a 108kg obese individual with sepsis is not explicitly stated in the label. However, considering the patient's obesity, the usual daily intravenous dose of 2 g divided either as 500 mg every 6 hours or 1 g every 12 hours may need to be modified. Key considerations for dosing include:

• Obesity: may require modification of the usual dose
• Renal function: dosage adjustment must be made in patients with impaired renal function
• Infusion rate: no more than 10 mg/min to minimize infusion-related events Given the lack of explicit dosing guidance for obese patients, a conservative approach would be to use the usual daily dose of 2 g, while closely monitoring the patient's renal function and vancomycin serum concentrations to adjust the dose as needed 6.

From the Research

Vancomycin Dosing for Obese Individuals with Sepsis

To determine the appropriate vancomycin dose for a 108kg obese individual with sepsis, several studies provide relevant information:

• A study published in 2020 7 characterized vancomycin pharmacokinetics in obese patients with sepsis or septic shock and developed a novel pharmacokinetic dosing model. However, it does not provide a specific dose recommendation for a 108kg individual.
• A systematic review published in 2023 8 highlighted the current dosing strategy of vancomycin among obese patients and recommended the administration of a loading dose (20-25 mg/kg) followed by a maintenance dose (15-25 mg/kg) of vancomycin in adult patients.
• A prospective study published in 2020 9 quantified vancomycin pharmacokinetics in morbidly obese and nonobese individuals and recommended a dose of 35 mg/kg/day (maximum 5500 mg/day) for obese individuals without renal impairment.
• A study published in 2024 10 provided AUC-targeted dosing recommendations for vancomycin in overweight and obese patients with varying degrees of renal (dys)function. The study suggested that maintenance doses should be adjusted for total body weight, renal function, and ICU admission status.

Dosing Recommendations

Based on the available evidence, the following dosing recommendations can be considered:

• Loading dose: 20-25 mg/kg 8
• Maintenance dose: 15-25 mg/kg 8 or 35 mg/kg/day (maximum 5500 mg/day) 9
• For a 108kg individual, the loading dose would be approximately 2160-2700 mg, and the maintenance dose would be approximately 1620-2700 mg/day or 3780 mg/day (using the 35 mg/kg/day recommendation)

Considerations

When determining the vancomycin dose for an obese individual with sepsis, it is essential to consider the following factors:

• Renal function: Vancomycin clearance is affected by renal function, and doses may need to be adjusted accordingly 7, 10
• Total body weight: Vancomycin pharmacokinetics are influenced by total body weight, and doses should be calculated based on this parameter 9, 10
• ICU admission status: Vancomycin clearance may be lower in ICU patients, and doses may need to be adjusted accordingly 10