Comparison of Ultrafiltration Devices for Assessing Theophylline Protein Binding

Blanchard, James; Harvey, Suzanne

doi:10.1097/00007691-199007000-00017

Cited by 16 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Chromatographic separation was performed on a Prominence modular HPLC (Shimadzu, Duisburg, Germany) as previously described, but using a Kinetex 2.6 µm C18 100 × 3 mm analytical column (Phenomenex, Aschaffenburg, Germany) and a flow rate of 0.4 mL/min . Linearity of the calibration function of the analytical method (sample preparation, ultrafiltration and HPLC) was proven both in serum of healthy subjects (2.5–50 mg/L vancomycin, r > 0.999) and in protein‐free iso‐osmotic phosphate buffer of pH 7.4 (0.5–50 mg/L vancomycin, r > 0.999) . The recovery from the buffer was 97.4 ± 1.9% independent of vancomycin concentration, indicating the absence of relevant adsorption of vancomycin to the filter device.…”

Section: Methodsmentioning

confidence: 99%

“…9 Linearity of the calibration function of the analytical method (sample preparation, ultrafiltration and HPLC) was proven both in serum of healthy subjects (2.5-50 mg/L vancomycin, r > 0.999) and in protein-free iso-osmotic phosphate buffer of pH 7.4 (0.5-50 mg/L vancomycin, r > 0.999). 10,11 The recovery from the buffer was 97.4 AE 1.9% independent of vancomycin concentration, indicating the absence of relevant adsorption of vancomycin to the filter device. No difference was observed between plasma and serum samples.…”

Section: Sample Treatment Ultrafiltration and Quantitative Analysesmentioning

confidence: 95%

See 1 more Smart Citation

Unbound fraction of vancomycin in intensive care unit patients

Kees

Wicha

Seefeld

et al. 2013

The Journal of Clinical Pharma

View full text Add to dashboard Cite

Published data on the unbound fraction of vancomycin in patient samples exhibit high variability. In the present study, a robust ultrafiltration method was developed and applied to 102 clinical samples from 22 intensive care unit patients who were treated with continuous infusion of vancomycin. A validated HPLC method was used for determination of total and unbound concentrations. The mean unbound fraction was 67.2% (standard deviation 7.5%, range 47.2-92.1%) and independent of total concentration of vancomycin or of albumin. The unbound fraction was significantly correlated (r = +0.67, P = .0009) with the renally filtered fraction (drug clearance/creatinine clearance), providing functional evidence for the validity of the measurements. Ultrafiltration proved to be susceptible to variations in the experimental conditions such as pH, temperature and centrifugal force. The measured unbound fraction increased from 60% at pH 6 to 100% at pH 9, from 57% at 4°C to 80% at 37°C, and was 76% at 1,000 g compared with 45% at 10,000 g. Lack of standardization may therefore partly explain the variable results reported in the literature.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Sample Treatment Ultrafiltration and Quantitative Analysesmentioning

confidence: 95%

Unbound fraction of vancomycin in intensive care unit patients

Kees

Wicha

Seefeld

et al. 2013

The Journal of Clinical Pharma

View full text Add to dashboard Cite

show abstract

“…18 Meanwhile, the membrane-binding sites are non-selective and readily saturated. Lee et al reported that pretreatment of UF membranes with Tween 80 or benzalkonium chloride successfully decreased the severe non-specific binding problems of some lipophilic drugs.…”

Section: Free and Bound Drug Concentrations In Plasma By Uf-lc/ms/ms 43mentioning

confidence: 99%

“…The UF method is substantially faster, but in some cases is limited by non-specific binding of drugs to the filter membranes. 18,19 Several studies have described the use of UF to isolate free drug molecules from plasma samples, followed by high-performance liquid chromatography (HPLC) or LC/MS analysis. [20][21][22][23][24] However, these methods are generally labor intensive and time consuming, resulting in low sample throughput.…”

mentioning

confidence: 99%

“…Sample throughput has been increased by the design of an ED system that is compatible with 96‐well laboratory supplies and instruments,14–17 but the protocol still requires several hours to achieve equilibrium. The UF method is substantially faster, but in some cases is limited by non‐specific binding of drugs to the filter membranes 18, 19. Several studies have described the use of UF to isolate free drug molecules from plasma samples, followed by high‐performance liquid chromatography (HPLC) or LC/MS analysis 20–24.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Rapid and direct measurement of free concentrations of highly protein‐bound fluoxetine and its metabolite norfluoxetine in plasma

Guo

Wang

et al. 2005

Rapid Comm Mass Spectrometry

View full text Add to dashboard Cite

Fluoxetine (F) and its active N-demethylated metabolite, norfluoxetine (NF), are selective serotonin re-uptake inhibitors that bind extensively to plasma proteins. Development and validation of a novel method for measuring free concentrations of F and NF in plasma are reported here. The plasma filtrate was prepared by a high-speed short-duration ultrafiltration (UF) and then submitted directly to a short-column liquid chromatography/tandem mass spectrometric (LC/MS/MS) assay. There was no significant matrix effect on the analysis, and non-specific binding of the analytes to the UF devices was negligible. For validation of the method, the recovery of the free analytes was compared to that from an optimized equilibrium dialysis method, and analyte stability was examined under conditions mimicking the sample storage, handling, and analysis procedures. The linearity range was 0.37-12 ng/mL for F and NF; the within-run and between-run relative standard deviations were less than 11.9%, and accuracies across the assay range were 100 +/- 10.3%. This new method was then further validated in a pharmacokinetic (PK) study in beagle dogs receiving a single oral dose of fluoxetine hydrochloride. The integrity of the resulting PK data of free F and NF was absolute. The PK data indicate that the novel method is accurate and reliable. To our knowledge this is the first report describing a rapid and reliable method for direct measurement of free concentrations of F and NF in plasma, which will be useful for clinical pharmacokinetic/pharmacodynamic studies of F. Furthermore, the strategies described herein may be applied to the development and validation of methods for measuring the free concentrations of other drugs in plasma.

show abstract

Plasma Protein Binding Methods in Drug Discovery and Development: Bioanalysis

Cohen

Nicoll‐Griffith

2012

Encyclopedia of Drug Metabolism and Interactions

View full text Add to dashboard Cite

This chapter provides an overview of both conventional and unconventional methods to determine plasma protein binding. Experiments using plasma protein binding advance our understanding of ADME properties to aid in drug candidate selection and development by determination of the unbound drug blood concentrations as well as (potentially) drug concentration at the site of action. Recent progress in automation as well as increased routine performance of the analytical instrumentation has enabled a greater number of compounds to be assayed earlier in discovery, and often with high enough quality to obviate the need for repeat studies during development. Significant effort has been invested to search for high throughput screening methods that reliably and accurately determine protein binding in early drug discovery. The development of 96‐well formats for equilibrium dialysis, ultrafiltration and ultracentrifugation, combined with liquid handling automation have transformed a formerly tedious, labor‐intensive assay into a process that can now be swiftly conducted. In addition, new approaches, referred to as emerging techniques, are also under investigation including chromatographic methods such as the human serum albumin column, spectroscopic methods including surface plasma resonance, solid phase microextraction, Transil™ membrane screening, and capillary electrophoresis methods. Several challenges still remain unsolved, particularly in cases of high protein binding with low exposure levels that fall below the normal limit of quantitation. This chapter describes the impact of high (>99%), undeterminable protein binding on compound developability as well as possible solutions including plasma dilution techniques.

show abstract

Comparison of Ultrafiltration Devices for Assessing Theophylline Protein Binding

Cited by 16 publications

References 0 publications

Unbound fraction of vancomycin in intensive care unit patients

Unbound fraction of vancomycin in intensive care unit patients

Rapid and direct measurement of free concentrations of highly protein‐bound fluoxetine and its metabolite norfluoxetine in plasma

Plasma Protein Binding Methods in Drug Discovery and Development: Bioanalysis

Contact Info

Product

Resources

About