From the FDA Drug Label
DOSAGE AND ADMINISTRATION ... Patients with Impaired Renal Function and Elderly Patients Dosage adjustment must be made in patients with impaired renal function. In premature infants and the elderly, greater dosage reductions than expected may be necessary because of decreased renal function Measurement of vancomycin serum concentrations can be helpful in optimizing therapy, especially in seriously ill patients with changing renal function. The initial dose should be no less than 15 mg/kg, even in patients with mild to moderate renal insufficiency. When only serum creatinine is known, the following formula (based on sex, weight and age of the patient) may be used to calculate creatinine clearance.
The recommended dose of vancomycin for a 100-year-old female patient with a urinary tract infection (UTI) is not directly stated, but dosage adjustment is necessary due to impaired renal function in the elderly.
- The initial dose should be no less than 15 mg/kg.
- To determine the appropriate dose, creatinine clearance should be calculated using the provided formula, taking into account the patient's sex, weight, and age.
- Vancomycin serum concentrations should be measured to optimize therapy, especially in patients with changing renal function. 1
From the Research
For a 100-year-old female with a UTI requiring vancomycin, I recommend an initial dose of 15-20 mg/kg actual body weight (typically 1 gram IV every 12-24 hours), with subsequent dosing adjusted based on renal function. In elderly patients, especially those over 90 years old, renal function is often significantly decreased, so starting at the lower end of the dosing range and extending the interval to every 24 hours may be appropriate. Some key points to consider when treating UTIs in elderly patients include:
- The diagnosis of UTI should be based on clinical features and laboratory evidence of a urinary infection, as asymptomatic bacteriuria is common in this population and should not be treated 2.
- The choice of antibiotic should be guided by local resistance patterns and the patient's individual risk factors for resistance 3, 4.
- Vancomycin is typically reserved for UTIs caused by resistant gram-positive organisms like MRSA or when first-line therapies have failed, as it has limited urinary excretion and potential nephrotoxicity, which is particularly concerning in very elderly patients.
- Renal function should be closely monitored throughout treatment using serum creatinine and estimated glomerular filtration rate, with dose adjustments made accordingly.
- Obtain a trough level just before the fourth dose (or third dose if dosing every 24 hours) to ensure steady state has been reached, with target trough levels of 10-15 mg/L for uncomplicated UTIs or 15-20 mg/L for complicated infections. It's also important to note that the evidence for vancomycin dosing in elderly patients with UTIs is limited, and the recommended dose may need to be adjusted based on individual patient factors, such as renal function and comorbidities 5, 6.