What is the appropriate vancomycin dosing regimen for a 140‑lb (≈63.5 kg) adult with normal renal function?

Vancomycin Dosing for a 140-lb (63.5 kg) Adult Patient

For a 140-lb (63.5 kg) adult with normal renal function, administer vancomycin 950-1,270 mg IV every 8-12 hours (calculated as 15-20 mg/kg per dose), with the specific dose and interval determined by infection severity and target trough concentrations. 1

Weight-Based Dosing Calculation

• For this 63.5 kg patient, the dose range is 950-1,270 mg per dose (15-20 mg/kg × 63.5 kg), not to exceed 2 g per dose 1
• Round to practical doses: 1,000 mg every 12 hours for non-severe infections or 1,000-1,250 mg every 8-12 hours for serious infections 1, 2
• The traditional fixed dose of 1 g every 12 hours is appropriate for this patient weight and represents the lower end of weight-based dosing 1, 3

Loading Dose Considerations

• For serious infections (bacteremia, endocarditis, pneumonia, necrotizing fasciitis), administer a loading dose of 1,590-1,905 mg (25-30 mg/kg) to rapidly achieve therapeutic concentrations 1
• Infuse the loading dose over 2 hours to minimize infusion-related reactions 1
• The loading dose is not affected by renal function and should be given at full weight-based dosing even if renal impairment develops 1

Target Trough Concentrations

• For serious infections: target trough 15-20 mg/L 1, 3
• For non-severe infections: target trough 10-15 mg/L 1
• Obtain trough concentrations before the fourth or fifth dose to assess adequacy and guide adjustments 1, 3

Infusion Rate Guidelines

• Infuse doses ≤1 g over at least 60 minutes 2
• For doses >1 g, extend infusion to 1.5-2 hours to minimize red man syndrome 1, 2
• Maximum infusion rate should not exceed 10 mg/min 2

Dosing Interval Selection

• Every 12 hours is appropriate for most patients with normal renal function and non-severe infections 1, 2
• Every 8 hours may be needed for serious infections or to achieve higher trough concentrations of 15-20 mg/L 1
• The choice between 8-hour and 12-hour intervals depends on the target trough level and infection severity 1, 3

Therapeutic Monitoring Algorithm

1. Draw first trough before the fourth dose (at steady state) 1, 3
2. If trough is 10-15 mg/L and treating non-severe infection: maintain current regimen 1
3. If trough is 15-20 mg/L and treating serious infection: maintain current regimen 1
4. If trough is <10 mg/L: increase dose or shorten interval 1
5. If trough is >20 mg/L: hold next dose, recheck trough, then reduce dose or extend interval 1

Critical Pitfalls to Avoid

• Never use fixed 1-gram doses without considering patient weight—this results in underdosing in patients >70 kg and potential overdosing in smaller patients 1
• Do not target trough levels of 15-20 mg/L for non-severe infections—this unnecessarily increases nephrotoxicity risk without improving outcomes 1
• Avoid combining vancomycin with other nephrotoxic agents (aminoglycosides, piperacillin-tazobactam, NSAIDs) when possible, as this significantly increases nephrotoxicity risk 1
• If vancomycin MIC is ≥2 μg/mL, switch to alternative therapy (daptomycin, linezolid, or ceftaroline) as target AUC/MIC ratios are unlikely to be achievable 1, 3

Practical Dosing Recommendation for This Patient

For non-severe infections: 1,000 mg IV every 12 hours, infused over 60 minutes, targeting trough 10-15 mg/L 1, 2

For serious infections: Give loading dose of 1,750 mg IV over 2 hours, then 1,250 mg IV every 12 hours (or 1,000 mg every 8 hours), targeting trough 15-20 mg/L 1