Quantitation of intracellular zidovudine phosphates by use of combined cartridge-radioimmunoassay methodology

Abstract

This report describes the development of a potentially clinical method to measure the cellular metabolites of zidovudine (ZDV) in patients receiving the drug. This new method combines the use of Sep-Pak cartridges to separate ZDV phosphates with radioimmunoassaying to quantitate ZDV. The detection limit is 0.02 pmol/10(6) cells, and this assay can measure a wide range of intracellular drug concentrations. The use of the cartridge-radioimmunoassay methodology should prove very useful for in vivo cellular pharmacokinetic studies of ZDV.

Fully validated assay for the quantification of endogenous nucleoside mono- and triphosphates using online extraction coupled with liquid chromatography–tandem mass spectrometry

“…The most common approaches for solid-phase extraction of nucleotides or phosphates metabolites of nucleoside analogs are based on anion exchange mechanism, using offline device [3,[14][15][16]. Online extraction assay development was based on our previous method using offline solid-phase extraction with Oasis® WAX cartridge [3].…”

“…The first step of the analytical workflow for the study of intracellular nucleotides consists in a protein precipitation using various solvents such as 60 or 70 % methanol, trichloroacetic acid or perchloric acid (review in [13]). Thereafter, some authors perform a solid-phase extraction using anion exchange cartridge to isolate selectively nucleotides or phosphate metabolites of nucleoside analogs [3,[14][15][16]. However, this extraction step is time consuming and causes variability in repeatability and reproducibility.…”

Simultaneous measurement of intracellular triphosphate metabolites of zidovudine, lamivudine and abacavir (carbovir) in human peripheral blood mononuclear cells by combined anion exchange solid phase extraction and LC–MS/MS

“…In this paper, we describe a new procedure, which represents an adaptation of separation techniques previously described by us, in which cartridge-RIA methods were used to measure ZDV-TP and 3TC-TP [6,10]. The new procedure relies on LC-MS/MS as the detection methodology.…”

“…In order to circumvent the HPLC part of the assay we developed SPE anion exchange cartridge fractionation linked with RIA. This allowed several samples to be fractionated simultaneously [6]. Because the antibody kit for detection of ZDV is no longer available, we and others have turned to LC-MS/MS as a method of detection [7][8][9] since it provides good sensitivity.…”

Determination of some anti-human immunodeficiency virus nucleosides by capillary zone electrophoresis-tandem mass spectrometry

“…Thus, analytical methods are needed for simultaneously determining blood levels for the drugs used in the present HIV polytherapy. Several methods have been developed for the analysis of the nucleosides [8][9][10] and, in the field of HIV therapy, LC-UV [11,12], radioimmunoassay [13,14], or LC-MS/MS [15][16][17] has performed them. Each method (individual or simultaneous) involves also a sample preparation procedure: liquid-liquid or solid-liquid extraction, or protein precipitation.…”