Simplified Methods for Estimation of Plasma Clearance of Iohexol in Dogs and Cats

Abstract

The purpose of this study was to evaluate simplified methods for iohexol plasma clearance estimation in dogs and cats. Serial blood samples were taken before and 5, 20, 40, 60, 80, 100, 120, 150, 180, and 240 minutes after a bolus injection of iohexol in 51 dogs and 25 cats. Iohexol plasma concentration was determined with X-ray fluorescence. Clearance was calculated by dividing the injected dose by the area under the plasma tracer elimination curve estimated with a 2-compartment pharmacologic model. Clearance was normalized to body surface area (BSA). The 10-point clearance was used as a reference for the evaluation of simplified methods. A 2-sample method based on a single exponential fit and a single-sample method based on a linear quadratic model were investigated. Simplified methods were evaluated by calculating the standard deviation of the difference (SDD) between the clearances obtained with the simplified methods and the 10-point reference method. All combinations of sampling times were evaluated. The best sampling times were chosen for dogs and cats as the ones yielding the lowest SDD. Linear regression analysis was performed between the reference method and the optimized simplified methods. The best combination of time for the 2-sample method was 5 and 120 minutes in dogs and 20 and 180 minutes in cats. The best time for sampling in the single-sample method was 120 minutes in dogs and 80 minutes in cats. Plasma clearance of iohexol can be estimated in dogs and cats from 1 or 2 blood samples with a reasonable margin of error.

Effect of MK‐467 on organ blood flow parameters detected by contrast‐enhanced ultrasound in dogs treated with dexmedetomidine

“…This observation is also supported by the iohexol plasma concentrations. Although glomerular filtration rate (GFR) was not calculated in this study, the differences in iohexol plasma concentrations between the treatments suggested that the decrease in the GFR after DEX was alleviated by MK-467, as GFR inversely correlates with iohexol plasma concentration (Gleadhill & Michell 1996;Goy-Thollot et al 2006a). Thus, the addition of MK-467 could be beneficial for kidneys and GFR since this compound alleviates the effects of DEX on renal blood flow.…”

Evaluation of a Single Sampling Method for Estimation of Plasma Iohexol Clearance in Dogs and Cats with Various Kidney Functions

“…In the present study, the numerous animals (779 dogs and 339 cats) used may provide the requisite accuracy for the regression equation to calculate PCio single . Some studies using iohexol and 99m Tc-DTPA showed that optimal sampling times were similar in dogs (120 min) and cats (80 or 90 min) [1,17]. In another study using 51 Cr-EDTA in cats [33], the optimal sampling time was 48 min.…”

“…In the present study, PCio estimated by a single sample was made available for detection of decreased GFR in dogs and cats. The utility of the single sampling method has been reported in dogs, cats, and humans [1,17,28,31,33]. Goy-Thollot et al [17] showed that PCio determined by a single sample was significantly correlated with PCio determined by the 2 CM (10 samples) in dogs and cats.…”

“…Therefore, the development of a simpler procedure for assessing plasma clearance is necessary to allow the frequent measurement of GFR in clinical settings. The single sampling methods for plasma clearance of iohexol, Tc-DTPA, 51 Cr-EDTA, and 131 I-orthoiodohippurate (OIH) are the simplest methods and have been reported in dogs and cats [1,17,33]. The purpose of this study was to evaluate a single sampling method for the estimation of PCio in dogs and cats with various kidney functions.…”

Serum Clearance of Iodixanol for Estimating Glomerular Filtration Rate in Calves

“…Therefore, only a few studies have reported GFR measurements in calves [15]. Plasma clearance of the nonionic monomeric X-ray contrast medium iohexol is used as a standard for estimating GFR in small animal practice [3,5,7], whereas a concern regarding further deterioration of impaired renal function has been reported in humans [2], presumably due to its relatively high osmolarity (osmolar ratio: approximately 2). Here, we focused on the isotonic nonionic dimeric X-ray contrast medium iodixanol as a new tracer for estimating calf GFR.…”