Determination of dexamethasone and dexamethasone sodium phosphate in human plasma and cochlear perilymph by liquid chromatography/tandem mass spectrometry.
A rapid, simple and sensitive liquid chromatography/tandem mass spectrometry (LC-MS/MS) assay was developed for the determination of dexamethasone (Dex) and dexamethasone sodium phosphate (Dex SP) in plasma and human cochlear perilymph. After proteins were precipitated with a mixture of acetonitrile and methanol, Dex, Dex SP and flumethasone, the internal standard, were resolved on a C18 column using gradient elution of 5 mM ammonium acetate and methanol. The three compounds were detected using electrospray ionisation in the positive mode. Standard curves were linear over the concentration range 0.5-500 μg/L (r>0.99), bias was <±10%, intra- and inter-day coefficients of variation (imprecision) were <10%, and the limit of quantification was 0.5 μg/L for both Dex and Dex SP. The assay has been used successfully in a clinical pharmacokinetics study of Dex and Dex SP in cochlear perilymph and plasma.
Department of Medicine, University of Otago-Christchurch, Christchurch, New Zealand. mei.zhang@cdhb.govt.nz
Mei
M
Zhang
Grant A
GA
Moore
Berit P
BP
Jensen
Evan J
EJ
Begg
Philip A
PA
Bird
D002853:Chromatography, Liquid / Q000379:methods*; D003051:Cochlea / Q000737:chemistry*; D003907:Dexamethasone / Q000031:analogs & derivatives* / Q000032:analysis* / Q000097:blood / Q000737:chemistry; D004355:Drug Stability; D005443:Flumethasone / Q000032:analysis; D006801:Humans; D016014:Linear Models; D010498:Perilymph / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry / Q000379:methods*
C004180:dexamethasone 21-phosphate; D003907:Dexamethasone; D005443:Flumethasone