What is the recommended vancomycin dosing regimen for a 52-year-old male weighing 116 kg with impaired renal function undergoing peritoneal dialysis?

Vancomycin Dosing in Peritoneal Dialysis

Loading Dose Recommendation

For this 52-year-old male weighing 116 kg on peritoneal dialysis, administer a single intraperitoneal loading dose of approximately 30 mg/kg (3,480 mg, rounded to 3,500 mg) of vancomycin. 1

• The loading dose should be based on actual body weight, calculated as approximately 30 mg/kg, which for this patient equals 3,480 mg (can be rounded to 3,500 mg for practical administration) 1
• This loading dose is administered intraperitoneally at the time of diagnosis or initiation of therapy 1, 2
• The loading dose is not affected by renal function and should be given at full weight-based dosing even in patients with end-stage renal disease 3

Maintenance Dosing Strategy

After the loading dose, add vancomycin 30 mg/L to each dialysate exchange bag for continuous therapy. 2

Two Evidence-Based Approaches:

Continuous dosing (preferred for reliability):

• Add 30 mg/L vancomycin to each dialysate bag after the initial loading dose 2
• This approach ensures consistent intraperitoneal concentrations above the MIC for gram-positive organisms 1
• Clinical resolution typically occurs within 3.2 days of therapy initiation 2

Intermittent dosing (alternative):

• Administer a second intraperitoneal dose of 30 mg/kg (3,500 mg) one week after the initial loading dose 2
• However, this approach may not consistently maintain therapeutic intraperitoneal levels, as 23% of patients had vancomycin levels below 4 mg/L (the MIC for many gram-positive organisms) at day 5 1

Critical Clinical Considerations

The continuous dosing approach is more reliable than intermittent dosing for maintaining therapeutic intraperitoneal concentrations. 1

• Intermittent dosing (single dose every 5-7 days) cannot guarantee therapeutic peritoneal dialysate effluent levels, with nearly one-quarter of patients showing subtherapeutic concentrations 1
• The correlation between serum and peritoneal dialysate effluent vancomycin concentrations is poor (R² = 0.18), meaning adequate serum levels do not guarantee adequate intraperitoneal levels 1
• Continuous dosing with 30 mg/L in each exchange provides more consistent therapeutic levels throughout treatment 2

Therapeutic Monitoring

Monitor serum vancomycin trough levels to ensure they remain above 12-15 mg/L, but recognize this does not guarantee adequate intraperitoneal concentrations. 1

• Target serum trough concentrations of 15-20 mg/L for serious infections 3
• Serum levels exceeding 12 mg/L were achieved in 98% of patients with intermittent dosing, but this did not correlate with adequate intraperitoneal levels 1
• Consider measuring peritoneal dialysate effluent vancomycin concentrations if clinical response is suboptimal 1

Common Pitfalls to Avoid

• Do not use fixed 1-gram doses regardless of patient weight, as this results in subtherapeutic levels in most patients, especially those weighing >70 kg 3
• Do not rely solely on serum vancomycin levels to guide therapy for peritoneal dialysis-associated peritonitis, as serum levels correlate poorly with intraperitoneal concentrations 1
• Do not assume intermittent dosing will maintain therapeutic intraperitoneal levels throughout the treatment course, as efflux from serum to peritoneal dialysate is inconsistent 1
• Do not reduce the loading dose based on renal function or dialysis status, as the loading dose is designed to rapidly achieve therapeutic concentrations and is not affected by renal impairment 3

Administration Details

• Infuse vancomycin over at least 60 minutes to minimize red man syndrome risk 4
• Consider antihistamine premedication for large loading doses (>2 grams) 3
• The infusion rate should not exceed 10 mg/min in adults 4