Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p><jats:bold>Objective</jats:bold>—To determine whether a glomerular filtration rate (GFR) assay based on serum iohexol clearance can be used to predict carboplatin clearance in cats.</jats:p>
<jats:p><jats:bold>Animals</jats:bold>—10 cats with tumors.</jats:p>
<jats:p><jats:bold>Procedures</jats:bold>—GFR was measured concurrently by use of plasma clearance of technetium Tc 99m–labeled diethylenetriaminepentaacetic acid (<jats:sup>99m</jats:sup>Tc-DTPA) to yield GFR<jats:sub>99mTc-DTPA</jats:sub> and serum clearance of iohexol to yield GFR<jats:sub>Iohexol</jats:sub>. A single dose of carboplatin was administered IV as a bolus. Dose was calculated by use of a target value for the area under the plasma platinum concentration-versus-time curve (AUC<jats:sub>Target</jats:sub>) and estimation of platinum clearance (CL<jats:sub>PT</jats:sub>) derived from GFR<jats:sub>99mTc-DTPA</jats:sub> as follows: dose = AUC<jats:sub>Target</jats:sub> × 2.6 × GFR<jats:sub>99mTc-DTPA</jats:sub> × body weight, where AUC<jats:sub>Target</jats:sub> is 2.75 min·mg·mL<jats:sup>−1</jats:sup>. Plasma platinum concentrations were measured via atomic absorption spectrophotometry. Values for GFR<jats:sub>99mTc-DTPA</jats:sub> and GFR<jats:sub>Iohexol</jats:sub> were compared by use of least-squares regression and Bland-Altman analysis. Least-squares regression was used to determine whether CL<jats:sub>PT</jats:sub> could be predicted from GFR<jats:sub>99mTc-DTPA</jats:sub> or GFR<jats:sub>Iohexol</jats:sub> (or both).</jats:p>
<jats:p><jats:bold>Results</jats:bold>—GFR<jats:sub>99mTc-DTPA</jats:sub> and GFR<jats:sub>Iohexol</jats:sub> were strongly correlated (<jats:italic>r</jats:italic> = 0.90), but GFR<jats:sub>Iohexol</jats:sub> values were significantly larger by a factor of approximately 1.4. Platinum clearance had a significant linear relationship to GFR<jats:sub>99mTc-DTPA</jats:sub> (CL<jats:sub>PT</jats:sub> = 2.5 × GFR<jats:sub>99mTc-DTPA</jats:sub>) and to GFR<jats:sub>Iohexol</jats:sub> (CL<jats:sub>PT</jats:sub> = [1.3 × GFR<jats:sub>Iohexol</jats:sub>] + 1.4).</jats:p>
<jats:p><jats:bold>Conclusions and Clinical Relevance</jats:bold>—In cats, serum iohexol clearance was an accurate predictor of CL<jats:sub>PT</jats:sub> and can be used to calculate the carboplatin dose as follows: dose = AUC<jats:sub>Target</jats:sub> × ([1.3 × GFR<jats:sub>Iohexol</jats:sub>] + 1.4) × body weight.</jats:p>