Merck

Measurement of plasma protein and lipoprotein binding of pyrethroids.

Journal of pharmacological and toxicological methods (2014-06-15)
Pankaj K Sethi, S Muralidhara, James V Bruckner, Catherine A White
ABSTRACT

A simple, reliable procedure was developed to measure binding of pyrethroid insecticides to total proteins and lipoproteins of rat and human plasma. The extent of binding of (14)C-labeled deltamethrin (DLM), cis-permethrin (CIS) and trans-permethrin (TRANS) was quantified by a 3-step organic solvent extraction technique. Rat and human plasma samples, containing NaF to inhibit esterases, were spiked with a range of concentrations of each radiolabeled pyrethroid. Protein binding reached equilibrium within ~1h of incubation at 37°C. The samples were extracted in turn with: isooctane to collect the unbound fraction; 2-octanol to extract the lipoprotein-bound fraction; and acetonitrile to obtain the protein-bound fraction. Absolute recoveries of DLM, CIS and TRANS ranged from 86 to 95%. Adherence of these very lipophilic chemicals to glass and plastic was minimized by using silanized glass vials and LoBind® plastic pipettes. The method's ability to distinguish lipoprotein from protein binding was confirmed by experiments with diazepam and cyclosporine, drugs that bind selectively to albumin and lipoproteins, respectively. This procedure was effectively utilized for studies of the species-dependence of plasma protein and lipoprotein binding of three pyrethroids for inclusion in physiologically-based pharmacokinetic models of pyrethroids for use in health risk assessments of the insecticides in children and adults.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Hexamethyldisilazane, produced by Wacker Chemie AG, Burghausen, Germany, ≥97.0% (GC)
Supelco
Acetonitrile, analytical standard
Supelco
Fluoride ion solution for ISE, 0.1 M F-, analytical standard (for ion-selective electrodes)
Supelco
Hexamethyldisilazane, for GC derivatization, LiChropur, ≥99.0% (GC)
Sigma-Aldrich
2,2,4-Trimethylpentane, anhydrous, 99.8%
Sigma-Aldrich
(±)-2-Octanol, ReagentPlus®, ≥99.5% (GC)
Supelco
2,2,4-Trimethylpentane, analytical standard
Sigma-Aldrich
Hexamethyldisilazane, ReagentPlus®, 99.9%
Sigma-Aldrich
Hexamethyldisilazane, reagent grade, ≥99%
Sigma-Aldrich
Acetonitrile, anhydrous, 99.8%
Sigma-Aldrich
(±)-2-Octanol, ≥96.0% (GC)
Sigma-Aldrich
Ultrapure Acetonitrile, for DNA synthesis
Sigma-Aldrich
Acetonitrile, for DNA synthesis
Sigma-Aldrich
Acetonitrile, for DNA synthesis
Supelco
Acetonitrile, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Ultrapure Acetonitrile
Sigma-Aldrich
Acetonitrile, electronic grade, 99.999% trace metals basis
Sigma-Aldrich
Acetonitrile, HPLC Plus, ≥99.9%
Sigma-Aldrich
Acetonitrile, for HPLC, for UV, ≥99.9% (GC)
Sigma-Aldrich
Acetonitrile, suitable for HPLC, gradient grade, ≥99.9%
Sigma-Aldrich
Acetonitrile, suitable for HPLC, gradient grade, ≥99.9%
Sigma-Aldrich
2,2,4-Trimethylpentane, suitable for HPLC, ≥99%
Sigma-Aldrich
2,2,4-Trimethylpentane, HPLC Plus, for HPLC, GC, and residue analysis, ≥99.5%
Sigma-Aldrich
Acetonitrile, suitable for HPLC-GC, ≥99.8% (GC)
Sigma-Aldrich
2,2,4-Trimethylpentane, puriss. p.a., ACS reagent, ≥99.5% (GC)
Sigma-Aldrich
Acetonitrile, biotech. grade, ≥99.93%
Sigma-Aldrich
Acetonitrile, ≥99.5% (GC)
Sigma-Aldrich
2,2,4-Trimethylpentane, ReagentPlus®, ≥99%
Sigma-Aldrich
2,2,4-Trimethylpentane, puriss. p.a., ≥99.5% (GC)
Sigma-Aldrich
Acetonitrile, ACS reagent, ≥99.5%