What is the recommended Vancomycin (Vancomycin hydrochloride) IV dose for treating serious bacterial infections, including those caused by Methicillin-resistant Staphylococcus aureus (MRSA)?

Vancomycin IV Dosing for Serious Bacterial Infections

For serious MRSA infections, vancomycin should be dosed at 15-20 mg/kg/dose (actual body weight) IV every 8-12 hours, not to exceed 2 g per dose, with target trough concentrations of 15-20 μg/mL. 1

Adult Dosing Algorithm

Standard Dosing

• Initial dose: 15-20 mg/kg/dose (actual body weight) IV every 8-12 hours in patients with normal renal function 1, 2
• Maximum dose: 2 g per dose 1
• Target trough levels:
  • 15-20 μg/mL for serious infections (bacteremia, endocarditis, osteomyelitis, meningitis, pneumonia, necrotizing fasciitis) 1, 2
  • 10-15 μg/mL for less severe infections 2

Loading Dose for Critically Ill Patients

• Loading dose: 25-30 mg/kg (actual body weight) for patients with sepsis, meningitis, pneumonia, or endocarditis 1
• Administration: Consider extending infusion time to 2 hours and using antihistamine premedication to reduce risk of red man syndrome 1

For Skin and Soft Tissue Infections (SSTI)

• For most uncomplicated SSTI with normal renal function and non-obese patients: 1 g every 12 hours is typically adequate 1
• Trough monitoring not required for uncomplicated SSTI 1

Pediatric Dosing

• Standard dose: 15 mg/kg/dose IV every 6 hours for serious or invasive disease 1
• Target trough levels: 15-20 μg/mL for serious infections (bacteremia, endocarditis, osteomyelitis, meningitis, pneumonia, severe SSTI) 1

Therapeutic Monitoring

• When to monitor: Trough concentrations should be obtained at steady state, prior to the 4th or 5th dose 1, 2
• Who needs monitoring: Patients with serious infections, morbid obesity, renal dysfunction (including those on dialysis), or fluctuating volume of distribution 1
• Peak monitoring: Not recommended 1

Duration of Therapy

• Meningitis: 2 weeks 1
• Brain abscess, subdural empyema, spinal epidural abscess: 4-6 weeks 1
• Bacteremia, endocarditis: Generally 4-6 weeks (individualize based on source control and clinical response) 2
• Skin and soft tissue infections: 7-14 days 2

Special Considerations

MIC-Based Adjustments

• For isolates with vancomycin MIC <2 μg/mL: Continue vancomycin based on clinical response 1
• For isolates with vancomycin MIC ≥2 μg/mL (VISA or VRSA): Switch to alternative agent 1

Treatment Failure

If inadequate clinical or microbiologic response despite appropriate dosing:

1. Ensure adequate source control (drainage, debridement) 1
2. Consider alternative agents:
   • Daptomycin 6-10 mg/kg/day IV (higher doses for serious infections) 1
   • Linezolid 600 mg PO/IV twice daily 1
   • TMP-SMX 5 mg/kg/dose IV twice daily 1

Potential Adverse Effects

• Nephrotoxicity: Higher risk with trough levels ≥15 mg/L (OR 2.14,95% CI 1.42-3.23) 3
• Red man syndrome: More common with rapid infusion; extend infusion time to 2 hours for large doses 1

Clinical Pearls

• Standard dosing of 1 g every 12 hours is often inadequate to achieve target trough concentrations of 15-20 mg/L in critically ill patients 4
• Higher trough levels (15-20 mg/L) are associated with lower microbiological failure rates but increased nephrotoxicity 5
• For pneumonia, particularly in critically ill patients, more aggressive dosing (e.g., 1 g every 8 hours) may be needed to achieve therapeutic levels 4
• Consider continuous infusion in select patients to optimize pharmacokinetics and potentially reduce nephrotoxicity 6

Remember that while higher vancomycin trough concentrations are associated with increased nephrotoxicity, this must be balanced against the risk of treatment failure in serious MRSA infections, where inadequate dosing can lead to increased morbidity and mortality.