Research ArticlesStabilization and HPLC Analysis of Betamethasone Sodium Phosphate in Plasma
Section snippets
INTRODUCTION
Administration of corticosteroids via the parenteral route for therapeutic purposes poses problems because of their limited aqueous solubility. To overcome this problem, corticosteroids have often been formulated as water-soluble hemisuccinate or phosphate ester prodrugs. These prodrugs are converted to the active steroid in vivo and the conversion is thought to occur rapidly and completely. Betamethasone (BET) in the form of its phosphate ester sodium salt is used in perinatal medicine.
Liquid Chromatography
The high-performance liquid chromatography (HPLC) system consists of a Waters model 510 pump, a Waters intelligent sample processor (model 717), and a model 486 Waters fixed wavelength UV detector (Waters Associates, Milford, MA). Analyte peaks are integrated using a Hewlett Packard (Avondale, PA) 3392A integrator. Separations are achieved using an Alltech Adsorbosphere HS (Alltech Associates, Inc., Deerfield, IL) C18 7 μm column (150 × 4.6 mm) attached to an Upchurch Scientific (Oak Harbor, WA)
Assay Characteristics and Validation
Published HPLC methods for measuring corticosteroids and their phosphate esters in plasma samples involve complex extraction procedures and utilize large sample volumes.3,7 Furthermore, determination of the prodrug requires either a second estimation step involving indirect estimation by hydrolysis to the steroid8 or a chromatographic method that makes use of highly acidic conditions to allow extraction and retention of the highly ionized phosphate prodrug.9 To circumvent these problems, an
Acknowledgements
The authors appreciate the provision of fresh blank sheep blood samples from the laboratory of Dr. Daniel Swartz of the University at Buffalo. This work was supported by grant GM24211 from the National Institutes of Health.
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LC-MS/MS determination of betamethasone and its phosphate and acetate esters in human plasma after sample stabilization
2011, Journal of Pharmaceutical and Biomedical AnalysisCitation Excerpt :Both esters are expected to be hydrolyzed in vivo to the active glucocorticoid BET [3]. Several analytical techniques have been published for the analysis of BET in different matrices, e.g., high performance liquid chromatography (HPLC) [3–5], gas chromatography with mass detection (GC–MS) [6,7] or liquid chromatography with mass detection (LC–MS/MS) [8–19]. The mentioned methods showed low sensitivity, e.g., 10, 50 and 300 ng/ml [3–5], implicated derivatization [6], were not fully validated or were not applicable to clinical or pharmacokinetic (PK) studies in human [12–19].
Betamethasone dose and formulation for induced lung maturation in fetal sheep
2009, American Journal of Obstetrics and GynecologyCitation Excerpt :Potassium fluoride was added and the plasma was frozen until analysis. The azide and fluoride were added to prevent the Beta-PO4 and Beta-Ac prodrugs from enzymatic cleavage to free Beta.14,15 Analyses for Beta, Beta-PO4, and Beta-Ac were performed by mass spectroscopic techniques by Analpharm, Quebec, Canada.
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2008, Journal of Chromatography B: Analytical Technologies in the Biomedical and Life SciencesBetamethasone for lung maturation: testing dose and formulation in fetal sheep
2007, American Journal of Obstetrics and GynecologyCitation Excerpt :Although the different preparations of Beta will have effects while the drug is in the circulation, this corticosteroid binds tightly to receptors and can have prolonged effects that extend well beyond plasma availability. A further complication for the interpretation of plasma levels of Beta is the presence of prodrug (Beta-PO4 or Beta-Ac) in plasma that may be hydrolyzed before assay, which will elevate plasma Beta levels artificially.20 The link between plasma corticosteroid levels and lung maturational responses in the fetus remains poorly characterized.
Stability of dexamethasone sodium phosphate in rat plasma
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