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Vancomycin assay performance in patients with acute renal failure
T N Trujillo1, K M Sowinski, R A Venezia
1Department of Pharmacy, Clarian Health Partners, Inc., Indianapolis, Indiana, USA.
Intensive Care Medicine
|February 2, 2000
Summary
The modified polyclonal fluorescence polarization immunoassay (pFPIA) shows reduced vancomycin overestimation. The monoclonal FPIA (mFPIA) is an acceptable assay for measuring vancomycin levels in acute renal failure patients.
Area of Science:
- Clinical Chemistry
- Pharmacokinetics
- Renal Medicine
Background:
- Fluorescence polarization immunoassays (FPIA) have historically overestimated vancomycin serum concentrations.
- This overestimation is particularly noted in patients with chronic renal disease when compared to HPLC or EMIT.
- Assay manufacturers have modified FPIA to address these discrepancies.
Purpose of the Study:
- To evaluate the performance of two modified Fluorescence Polarization Immunoassays (FPIA) against the Enzyme Multiplied Immunoassay Technique (EMIT).
- To assess these assays in critically ill patients with acute renal failure undergoing continuous venovenous hemofiltration.
- To determine if modified FPIAs provide accurate vancomycin serum concentration measurements in this patient population.
Main Methods:
- An open-label trial was conducted in an intensive care unit.
- Serum and ultrafiltrate samples were collected from 14 critically ill patients.
- Vancomycin concentrations were measured using a polyclonal FPIA (pFPIA), a monoclonal FPIA (mFPIA), and EMIT.
Main Results:
- The coefficient of variation for all assays was less than 5%.
- The mean difference between mFPIA and EMIT was -0.08 +/- 1.55 mg/l, with limits of agreement from -3.18 to 3.03 mg/l.
- The mean difference between pFPIA and EMIT was 1.24 +/- 2.11 mg/l, with limits of agreement from -2.99 to 5.46 mg/l.
Conclusions:
- Manufacturer modifications have successfully reduced the overestimation issues with the pFPIA.
- The mFPIA demonstrates acceptable performance for vancomycin measurement in patients with acute renal failure.
- The mFPIA does not significantly overestimate vancomycin serum concentrations in this clinical setting.