Determination of (22R,S)budesonide in human plasma by automated liquid chromatography/thermospray mass spectrometry.
(22R,S)Budesonide was isolated from human plasma by solid-phase extraction. Switching from reversed-phase conditions during sample application and washing to normal-phase conditions during elution afforded a very clean extract. Budesonide was derivatized with acetic anhydride to form the 21-acetyl derivative before analysis by reversed-phase liquid chromatography combined with thermospray mass spectrometry. Deuterium-labelled budesonide was used as internal standard. Standard samples prepared in human albumin solution were used for the calibration curve. An automated liquid chromatography/mass spectrometry system, allowing unattended overnight operation, was used for routine analysis. The recovery of budesonide from plasma was 88.9 +/- 5.9% (mean +/- SD) and the method was linear over the range 0.30-30 pmol (amount analysed), corresponding to plasma concentrations of 0.10-10 nmol l-1. Budesonide could be measured down to 0.10 nmol l-1 with a within-day variation of 10-18% (CV). The error was less than +/- 15% at 0.10 nmol l-1 and less than +/- 7% at concentrations of 0.20 nmol l-1 or higher. The total imprecision between days was 9% (CV) at a concentration of 0.30 nmol l-1.
Lindberg
C
C
Bioanalytical Chemistry, Astra Draco AB, Lund, Sweden.
Blomqvist
A
A
Paulson
J
J
D000287:Administration, Topical; D000893:Anti-Inflammatory Agents / Q000097:blood*; D019819:Budesonide; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D005938:Glucocorticoids; D006801:Humans; D066298:In Vitro Techniques; D011282:Pregnenediones / Q000097:blood*
D000893:Anti-Inflammatory Agents; D005938:Glucocorticoids; D011282:Pregnenediones; D019819:Budesonide