Limits...
A Limited Sampling, Simple, and Useful Method for Determination of Glomerular Filtration Rate in Cats by Using a New Accurate HPLC Method to Measure Iohexol Plasmatic Concentrations.

Valentina M, Grazia G, Pierre M, Gloria B, Ilaria L - J Vet Med (2013)

Bottom Line: IOX concentrations were determined by using a new HPLC-UV method.Correlation and agreement analysis between the GFR values obtained by a seven-point clearance method and the GFR values determined by the application of simplified sample combinations indicated that the 3-blood sample clearance model (5, 30, and 60 min) was the best simplified method because it provided an accurate GFR value in only one hour.The reported method is a simple and accurate way of GFR determination, which may be easily used in a clinical setting.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Clinics, University of Pisa, San Piero a Grado, Via Livornese Lato Monte, 56122 Pisa, Italy.

ABSTRACT
Glomerular filtration rate (GFR) is still a highly underutilized tool in cats because available methods are not easy to be performed in clinical practice. Iohexol (IOX) has been shown to be a useful and reliable marker of GFR both in animals and in humans. The aim of the present study was to develop a rapid and reliable method for measuring IOX in feline plasma and to evaluate the accuracy of limited sampling models to establish a low-cost and clinically suitable GFR test. IOX concentrations were determined by using a new HPLC-UV method. GFR was assessed as plasma clearance of IOX, which was calculated by dividing dose administered by area under the curve of plasmatic concentration versus time (AUC), and indexed to body weight (BW). Correlation and agreement analysis between the GFR values obtained by a seven-point clearance method and the GFR values determined by the application of simplified sample combinations indicated that the 3-blood sample clearance model (5, 30, and 60 min) was the best simplified method because it provided an accurate GFR value in only one hour. The reported method is a simple and accurate way of GFR determination, which may be easily used in a clinical setting.

No MeSH data available.


Related in: MedlinePlus

Chromatogram of the separation of IOX (10 μg/mL) and IS extracted from feline plasma; IS: internal standard.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4590869&req=5

fig1: Chromatogram of the separation of IOX (10 μg/mL) and IS extracted from feline plasma; IS: internal standard.

Mentions: Figure 1 illustrates chromatogram of IOX and IS in extracted feline plasma. IOX was eluted as two isomers endoiohexol and exoiohexol, at 6.4 and 6.8 min, respectively, whereas the IS was eluted as two isomers at 10.4 and 11.0 min. The specificity of the method was tested by analyzing feline plasma samples before the administration of IOX. No interfering peaks were observed at the elution times of IOX or IS isomers. IOX LOD and LOQ were found to be 0.01 and 0.1 μg/mL, respectively. Calibration graphs for IOX (n = 9) were constructed over the concentration range of 0.5–500 μg/mL and showed an average correlation coefficient (R2) of 0.999. The accuracy of the estimated IOX concentration was more than 90% at three concentrations. The precision expressed as interday coefficient of variation (CV%) ranged from 3.8% to 6.5% and as the intraday CV% ranged from 1.5% to 4.0% (Table 1). The extraction method of IOX from plasma samples had an average recovery ranging from 96.0 ± 2.5% to 95.0 ± 2.1% for low-to-high spiked samples (Table 1). The recovery was reproducible over seven replications performed over 7 different days. IS had an average recovery ranging from 96.0 ± 2.5% to 95.0 ± 1.5%. The concentrations of IOX in freeze-thaw and short-term stability evaluation were not significantly different from the fresh calibrators. The accuracy of the spiked samples ranged from 98% to 100% and from 98% to 101% after the freeze-thaw stability and short-term stability testing, respectively. The formal ruggedness test was conducted when the method was validated on a second HPLC system (Thermo Finnigan, Waltham, MA, USA) by another analyst (results not shown). Using the optimized parameters, the method was found to be equally robust.


A Limited Sampling, Simple, and Useful Method for Determination of Glomerular Filtration Rate in Cats by Using a New Accurate HPLC Method to Measure Iohexol Plasmatic Concentrations.

Valentina M, Grazia G, Pierre M, Gloria B, Ilaria L - J Vet Med (2013)

Chromatogram of the separation of IOX (10 μg/mL) and IS extracted from feline plasma; IS: internal standard.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4590869&req=5

fig1: Chromatogram of the separation of IOX (10 μg/mL) and IS extracted from feline plasma; IS: internal standard.
Mentions: Figure 1 illustrates chromatogram of IOX and IS in extracted feline plasma. IOX was eluted as two isomers endoiohexol and exoiohexol, at 6.4 and 6.8 min, respectively, whereas the IS was eluted as two isomers at 10.4 and 11.0 min. The specificity of the method was tested by analyzing feline plasma samples before the administration of IOX. No interfering peaks were observed at the elution times of IOX or IS isomers. IOX LOD and LOQ were found to be 0.01 and 0.1 μg/mL, respectively. Calibration graphs for IOX (n = 9) were constructed over the concentration range of 0.5–500 μg/mL and showed an average correlation coefficient (R2) of 0.999. The accuracy of the estimated IOX concentration was more than 90% at three concentrations. The precision expressed as interday coefficient of variation (CV%) ranged from 3.8% to 6.5% and as the intraday CV% ranged from 1.5% to 4.0% (Table 1). The extraction method of IOX from plasma samples had an average recovery ranging from 96.0 ± 2.5% to 95.0 ± 2.1% for low-to-high spiked samples (Table 1). The recovery was reproducible over seven replications performed over 7 different days. IS had an average recovery ranging from 96.0 ± 2.5% to 95.0 ± 1.5%. The concentrations of IOX in freeze-thaw and short-term stability evaluation were not significantly different from the fresh calibrators. The accuracy of the spiked samples ranged from 98% to 100% and from 98% to 101% after the freeze-thaw stability and short-term stability testing, respectively. The formal ruggedness test was conducted when the method was validated on a second HPLC system (Thermo Finnigan, Waltham, MA, USA) by another analyst (results not shown). Using the optimized parameters, the method was found to be equally robust.

Bottom Line: IOX concentrations were determined by using a new HPLC-UV method.Correlation and agreement analysis between the GFR values obtained by a seven-point clearance method and the GFR values determined by the application of simplified sample combinations indicated that the 3-blood sample clearance model (5, 30, and 60 min) was the best simplified method because it provided an accurate GFR value in only one hour.The reported method is a simple and accurate way of GFR determination, which may be easily used in a clinical setting.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Clinics, University of Pisa, San Piero a Grado, Via Livornese Lato Monte, 56122 Pisa, Italy.

ABSTRACT
Glomerular filtration rate (GFR) is still a highly underutilized tool in cats because available methods are not easy to be performed in clinical practice. Iohexol (IOX) has been shown to be a useful and reliable marker of GFR both in animals and in humans. The aim of the present study was to develop a rapid and reliable method for measuring IOX in feline plasma and to evaluate the accuracy of limited sampling models to establish a low-cost and clinically suitable GFR test. IOX concentrations were determined by using a new HPLC-UV method. GFR was assessed as plasma clearance of IOX, which was calculated by dividing dose administered by area under the curve of plasmatic concentration versus time (AUC), and indexed to body weight (BW). Correlation and agreement analysis between the GFR values obtained by a seven-point clearance method and the GFR values determined by the application of simplified sample combinations indicated that the 3-blood sample clearance model (5, 30, and 60 min) was the best simplified method because it provided an accurate GFR value in only one hour. The reported method is a simple and accurate way of GFR determination, which may be easily used in a clinical setting.

No MeSH data available.


Related in: MedlinePlus