What is the recommended dose of vancomycin (Vancomycin) for a 70-year-old patient with impaired renal function (creatinine level of 1.1)?

Vancomycin Dosing for a 70-Year-Old Patient with Creatinine of 1.1

For a 70-year-old patient with a creatinine of 1.1 mg/dL, the recommended vancomycin dose is 15 mg/kg IV every 12 hours, with each dose administered over at least 60 minutes. 1

Calculating the Appropriate Dose

Step 1: Estimate Creatinine Clearance

For a 70-year-old patient with a creatinine of 1.1 mg/dL, we need to calculate the creatinine clearance using the Cockcroft-Gault formula:

For women:

• CrCl = 0.85 × [Weight (kg) × (140 - age)] / [72 × serum creatinine (mg/dL)]

For men:

• CrCl = [Weight (kg) × (140 - age)] / [72 × serum creatinine (mg/dL)]

Assuming this is a 70 kg female patient:

• CrCl = 0.85 × [70 × (140 - 70)] / [72 × 1.1] ≈ 40 mL/min

Assuming this is a 70 kg male patient:

• CrCl = [70 × (140 - 70)] / [72 × 1.1] ≈ 47 mL/min

Step 2: Determine Appropriate Dosing

Based on the FDA-approved vancomycin dosing guidelines, the daily dose (mg) is approximately 15 times the glomerular filtration rate in mL/min 1:

For a female patient with CrCl of 40 mL/min:

• Daily dose ≈ 15 × 40 = 600 mg/day

For a male patient with CrCl of 47 mL/min:

• Daily dose ≈ 15 × 47 = 705 mg/day

This would typically be divided into two doses, resulting in approximately 300-350 mg every 12 hours.

Recommended Dosing Regimen

Given the patient's age (70) and moderate renal impairment, the following dosing regimen is recommended:

1. Initial dose: 15 mg/kg (based on actual body weight) 2

   • For a 70 kg patient: 15 × 70 = 1050 mg

2. Maintenance dose:

   • 600-700 mg IV every 12 hours (depending on gender)
   • Each dose should be administered over at least 60 minutes to minimize infusion-related reactions 1

3. Monitoring:

   • Check trough levels before the fourth dose (at steady state)
   • Target trough concentration: 15-20 mg/L for serious infections
   • Monitor renal function regularly (at least twice weekly)

Important Considerations

• Infusion Rate: Administer at no more than 10 mg/min or over at least 60 minutes (whichever is longer) to reduce the risk of infusion-related reactions 1

• Concentration: Use concentrations of no more than 5 mg/mL to minimize infusion-related events 1

• Monitoring: Regular monitoring of vancomycin serum concentrations is essential, especially in elderly patients, to optimize therapy and minimize toxicity 1

• Renal Function: Close monitoring of renal function is crucial as vancomycin can cause nephrotoxicity, particularly in elderly patients 3

• Dose Adjustment: Be prepared to adjust the dose based on trough levels and changes in renal function 1

Pitfalls to Avoid

1. Overestimating renal function: The Cockcroft-Gault formula may overestimate clearance in elderly patients, potentially leading to overdosing 4

2. Rapid infusion: Administering vancomycin too quickly can cause "red man syndrome" (flushing, hypotension, rash) 1

3. Inadequate monitoring: Failure to monitor drug levels and renal function can lead to toxicity or treatment failure 3

4. Fixed dosing: Using fixed doses rather than weight-based dosing can result in subtherapeutic or toxic levels 1

5. Ignoring age-related changes: Elderly patients often have decreased renal function even with "normal" creatinine levels 3