Vancomycin Dosing Recommendations
Adult Patients with Normal Renal Function
For adults with normal renal function and serious MRSA infections, administer a loading dose of 25-30 mg/kg (actual body weight) followed by maintenance dosing of 15-20 mg/kg every 8-12 hours, with a maximum single dose of 2 g, targeting trough concentrations of 15-20 μg/mL. 1
Standard Dosing Algorithm
Loading Dose (for serious infections):
- Administer 25-30 mg/kg based on actual body weight 1, 2, 3
- Infuse over 2 hours to minimize red man syndrome 1, 2
- Consider antihistamine premedication before large doses 1, 3
- The loading dose is NOT affected by renal function 1
Maintenance Dosing:
- 15-20 mg/kg (actual body weight) every 8-12 hours 1, 3
- Maximum single dose: 2 g 1, 3
- For non-severe infections in non-obese patients: 1 g every 12 hours is adequate 1
- For critically ill trauma patients with pneumonia: at least 1 g every 8 hours is needed 4
Target Trough Concentrations
Serious infections (bacteremia, endocarditis, osteomyelitis, meningitis, pneumonia, necrotizing fasciitis):
Non-severe infections (uncomplicated skin/soft tissue):
Therapeutic Monitoring Protocol
- Obtain trough levels at steady state, before the fourth or fifth dose (approximately 48-72 hours after initiation) 1, 3
- Draw trough immediately before the next dose, not simply 12 hours post-administration 1
- The pharmacodynamic target is AUC/MIC ratio >400, which correlates with troughs of 15-20 μg/mL 1, 3
Adult Patients with Impaired Renal Function
Administer the full loading dose of 25-30 mg/kg regardless of renal function, then extend the maintenance dosing interval based on creatinine clearance while maintaining the weight-based dose of 15-20 mg/kg. 1
Dosing Adjustments by Renal Function
- CrCl <30 mL/min (including dialysis): Extend interval to every 48 hours 1
- Hemodialysis patients: Administer doses after dialysis sessions 3
- Loading dose: Always give full 25-30 mg/kg—renal function does NOT affect loading dose 1
Monitoring in Renal Impairment
- Mandatory trough monitoring before the fourth dose 1
- Target troughs remain 15-20 μg/mL for serious infections 1
- For hemodialysis patients, obtain troughs immediately before the next dialysis session 3
Pediatric Dosing (≥1 month of age)
For children with serious or invasive MRSA infections, administer 15 mg/kg every 6 hours (60 mg/kg/day total), targeting trough concentrations of 15-20 μg/mL. 1, 3
Pediatric Dosing Regimens
- Serious/invasive infections: 15 mg/kg every 6 hours 1, 3
- Complicated intra-abdominal infections: 40 mg/kg/day divided every 6-8 hours 3
- Critically ill children: May require up to 60 mg/kg/day divided every 8 hours 3
- Children <12 years (linezolid alternative): 10 mg/kg every 8 hours 1
Infusion Duration
Standard infusion time is 60 minutes for doses ≤1 g; extend to 120 minutes for doses >1 g or loading doses to prevent red man syndrome. 1
Infusion Guidelines by Dose
- Doses ≤1 g: Infuse over minimum 60 minutes 1
- Doses >1 g: Infuse over 90-120 minutes 1
- Loading doses (25-30 mg/kg): Infuse over 120 minutes 1
- Surgical prophylaxis (30 mg/kg): Complete 120-minute infusion 30 minutes before incision 1
Special Population Considerations
Obese Patients
Always use actual body weight for all vancomycin calculations in obese patients—ideal body weight leads to dangerous underdosing. 1, 2, 3
- Fixed 1 g every 12 hours fails in patients >70 kg 1
- Patients with BMI ≥40 kg/m² require strict trough monitoring 1
- Class III obesity (BMI ≥40) carries 3-times higher nephrotoxicity risk 5
Critically Ill/Septic Patients
- Expanded volume of distribution from fluid resuscitation requires full loading doses 1
- Never reduce loading dose based on critical illness 1
- Target trough 15-20 μg/mL for sepsis 1
Alternative Agents (When to Switch)
If vancomycin MIC is ≥2 μg/mL, switch to an alternative agent immediately—target AUC/MIC >400 cannot be reliably achieved. 1, 2, 3
Alternative Options
Linezolid:
- 600 mg PO/IV twice daily (adults) 1, 2
- Superior for MRSA pneumonia due to better lung penetration 1
- Pediatric: 10 mg/kg every 8 hours (<12 years) 1
Daptomycin:
- High-dose 10 mg/kg once daily, often combined with another agent 1
- Preferred for persistent bacteremia or vancomycin failure 1
TMP-SMX:
- 5 mg/kg IV every 8-12 hours for serious MRSA infections 1
Telavancin:
- 10 mg/kg IV once daily for complicated skin/soft tissue infections 1
Critical Pitfalls to Avoid
Dosing Errors
- Never use fixed 1 g dosing in critically ill or obese patients—this produces subtherapeutic levels in most patients >70 kg 1
- Never reduce the loading dose for renal dysfunction—this is the most common error and delays therapeutic concentrations 1
- Never target 15-20 μg/mL troughs for non-severe infections—this unnecessarily increases nephrotoxicity risk 1, 3
Nephrotoxicity Risk Factors
- Troughs >15 μg/mL significantly increase nephrotoxicity, especially with concurrent nephrotoxic agents 1, 5
- Concomitant piperacillin-tazobactam, aminoglycosides, NSAIDs, CT contrast, and amphotericin B markedly increase risk 1
- Duration of therapy >7 days increases nephrotoxicity risk 5
- Class III obesity independently increases risk 3-fold 5
Clinical Failure Indicators
- Vancomycin has ≥40% failure rates for MRSA pneumonia with standard dosing—strongly consider linezolid first-line 1
- MIC ≥1.5 μg/mL is associated with increased mortality in MRSA bacteremia 1
- Lack of clinical response despite adequate source control warrants immediate switch to alternative agent 2
Dose Rounding Recommendations
For serious infections requiring weight-based dosing, round calculated doses UP to the nearest 250 mg increment (500 mg, 750 mg, 1 g, etc.) to achieve intended exposure. 1