What is the recommended vancomycin (Vancomycin) dose for a 90kg patient with normal renal function?

Vancomycin Dosing for a 90kg Patient with Normal Renal Function

For a 90kg patient with normal renal function, vancomycin should be dosed at 15-20 mg/kg (actual body weight) every 8-12 hours, which equates to approximately 1350-1800 mg every 8-12 hours. 1

Initial Dosing Recommendations

• For most adult patients with normal renal function, the recommended vancomycin dose is 15-20 mg/kg (actual body weight) every 8-12 hours 1
• For a 90kg patient, this translates to:
  • At 15 mg/kg: 1350 mg per dose
  • At 20 mg/kg: 1800 mg per dose 1
• For serious infections (e.g., bacteremia, endocarditis, meningitis, pneumonia), dosing should be every 8 hours to achieve higher trough concentrations 1, 2
• For less severe infections, dosing every 12 hours may be adequate 1

Loading Dose Considerations

• For seriously ill patients with suspected MRSA infection, consider a loading dose of 25-30 mg/kg (actual body weight) 3, 1
• For a 90kg patient, this would be 2250-2700 mg as the initial dose 1
• This loading dose helps achieve therapeutic concentrations more rapidly in critically ill patients 2

Therapeutic Monitoring

• Trough concentrations should be obtained at steady state, prior to the fourth or fifth dose 1, 2
• Target trough concentrations:
  • 15-20 μg/mL for serious infections (bacteremia, endocarditis, osteomyelitis, meningitis, pneumonia) 1, 2
  • 10-15 μg/mL for less severe infections 1
• The pharmacodynamic parameter that best predicts efficacy is AUC/MIC ratio >400 1, 4

Special Considerations for Obese Patients

• Weight-based dosing is particularly important in patients with higher body weight, who are likely to be underdosed when conventional dosing strategies of 1 g every 12 hours are used 1
• Standard fixed doses of 1 g every 12 hours are often inadequate, especially in patients weighing 90kg or more 5
• A study of critically ill patients found that even 1 g every 8 hours often failed to achieve target trough concentrations of 15-20 μg/mL 5

Common Pitfalls to Avoid

• Underdosing vancomycin can lead to treatment failure and promote resistance development 1
• Using fixed doses (e.g., 1 g every 12 hours) regardless of weight often results in subtherapeutic levels in larger patients 1, 5
• Failing to adjust dosing based on infection severity may result in inadequate drug exposure 1, 2
• Not considering the vancomycin MIC when setting target trough concentrations—alternative therapies should be considered when MIC is ≥2 μg/mL 3, 1

Practical Dosing Algorithm for a 90kg Patient

• For severe infections (e.g., suspected MRSA pneumonia, bacteremia):

  • Loading dose: 25-30 mg/kg = 2250-2700 mg (rounded to 2250 mg for practical administration) 1
  • Maintenance dose: 20 mg/kg every 8 hours = 1800 mg every 8 hours 1, 5
  • Target trough: 15-20 μg/mL 1, 2

• For less severe infections:

  • Initial dose: 15 mg/kg = 1350 mg (can be rounded to 1500 mg for practical administration) 1
  • Maintenance dose: 15 mg/kg every 12 hours = 1350 mg every 12 hours 1
  • Target trough: 10-15 μg/mL 1