Stable Isotope Dilution Mass Spectrometry Analysis of Endogenous and Synthetic Corticosteroids for the Pharmacokinetic and in vivo Metabolic Investigations in Humans

Abstract

This review article underlines the importance of stable isotope dilution mass spectrometry analysis of endogenous and synthetic corticosteroids for the pharmacokinetic and in vivo metabolic investigations in humans. The multi-labeled corticosteroids with stable isotopes such as H 4 ]cortisol, etc. have been used not only as analytical internal standard for the mass spectrometry but as tracer in the pharmacokinetic and metabolic studies in human in vivo. Stable isotope dilution analysis of cortisol metabolites (tetrahydrocortisol (THF), allo-tetrahydrocortisol (allo-THF), tetrahydrocortisone (THE), and 6β-hydroxycortisol (6β-OHF)) and synthetic corticosteroids (prednisolone, prednisone, budesonide, fluticasone, etc.) is also the subject of this review. In the gas chromatographic mass spectrometric (GC-MS) analysis of corticosteroids, it is usual to employ derivatives in which some or all of the original functional groups are protected. Thermal stabilization of corticosteroids in the analysis has been achieved most successfully by formation of methoxime-trimethylsilyl (MO-TMS) derivatives. Bismethylenedioxy-pentafluoropropionyl (BMD-PFP) derivatives have been developed to simultaneously measure cortisol, cortisone, and their tetrahydrocorticoid metabolites (THF, allo-THF, and THE) and/or prednisolone and prednisone in plasma and urine. Stable isotope tracer methodology has been applied to the measurements of cortisol production rate, determination of human urinary cortisol metabolites, and assessment of in vivo activities of 11β-hydroxysteroid dehydrogenase (11β-HSD) in humans. This methodology also has been used for the validity of endogenous cortisol 6β-hydroxylation clearance as a new index for phenotyping the in vivo cytochrome P450 3A (CYP3A) in humans.

Simultaneous determination of prednisolone, prednisone, cortisol, and cortisone in plasma by GC–MS: Estimating unbound prednisolone concentration in patients with nephrotic syndrome during oral prednisolone therapy

“…The mass spectrometric technique using stable isotope-labeled internal standards ensures the highest specificity and sensitivity, and a more accurate approach in determining a trace amount of endogenous and synthetic steroid compounds in biological fluids [23,[26][27][28]. One of the major advantages of this technique is that stable isotope-labeled internal standards practically behave in almost identical manner to the analyte through all steps in the extraction and chromatographic procedures thereby allowing procedural losses to be disregarded.…”

“…Stable isotopically labeled compounds, i.e., [1,2,4,19-13 C 4 ]prednisolone (prednisolone-13 C 4 , >97.3 atom% 13 C), [1,2,4,19-13 C 4 ]prednisone (prednisone-13 C 4 , >97.3 atom% 13 C), [1,1,19,19,19-2 H 5 ]cortisol (cortisol-2 H 5 , 98 atom% 2 H), and [1,1,19,19,19-2 H 5 ]cortisone (cortisone-2 H 5 , 98 atom% 2 H) were synthesized in our laboratory ( Fig. 1) [23][24][25]. Heptafluoro-n-butyric anhydride (HFBA) and paraformaldehyde were purchased from Pierce (Rockford, Illinois, USA) and Kanto (Tokyo, Japan), respectively.…”

“…However, 13 C-labeled compounds should preferably be used as internal standards for measurement of prednisolone and prednisone which have C1/C2 double bond in order to avoid the possible loss of a deuterium atom at C-1. Recently, we have synthesized 13 C-labeled prednisolone and prednisone (prednisolone-13 C 4 and prednisone-13 C 4 ) containing four 13 C at C-1, C-2, C-4 and C-19 with high isotopic purity (>97.3 atom% 13 C) [23]. In the present study, we have developed a sensitive and reliable GC-MS method for the simultaneous determination of prednisolone, prednisone, cortisol, and cortisone in plasma using 13 C 4 -labeled prednisolone and prednisone and 2 H 5 -labeled cortisol and cortisone as internal standards.…”