Quantitative analysis of RU38486 (mifepristone) by HPLC triple quadrupole mass spectrometry

A validated HPLC-MS/MS method for the quantification of systemic mifepristone after subcutaneous application in mice

Mifepristone (RU486, MIF) is a synthetic steroidal hormone with progesterone and glucocorticoid receptor antagonistic characteristics. MIF is commonly used for pharmalogical abortions, but also for the treatment of endometrial and endocrine disorders. The goal of the study was to establish and validate a targeted HPLC-MS/MS method for the quantification of MIF and one of its active metabolites metapristone (MET) in plasma after subcutaneous implantation of slow-release MIF pellets in female BALB/c mice. Additionally, we aimed to apply the analytical method to tissue of several organs to understand the tissue-specific distribution of both analytes after release into systemic circulation. Sample preparation comprised a simple liquid-liquid extraction with diethylether and required 100 μl of plasma or homogenates of approximately 50 mg of tissue. The presented HPLC-MS/MS method showed high sensitivity with baseline separation of MIF, MET, and the internal standard levonorgestrel within a run time of only 8.0 minutes and comparable limits of quantification for plasma and tissue homogenates ranging from 40 pg ml-1 to 105 pg ml-1 for MIF and MET. The presented study is suitable for murine plasma and tissues and can be easily applied to human samples.

New stability indicating RP-HPLC-PDA method for determination of mifepristone in bulk and tablet formulation

Background

Mifepristone is progestational and glucocorticoid hormone antagonist. The objective of this study is to develop simple and economical stability indicating RP-HPLC method for the determination of mifepristone in bulk and tablet formulation.

Result

The chromatographic separation was achieved on Qualisil BDS C8 column with mobile phase containing of mixture of Buffer (Potassium dihydrogen ortho phosphate, pH to 3.0 with ortho phosphoric acid) and Organic Solvent (Acetonitrile) 60:40 v/v pumped at flow rate 0.6 mL min−1. The detection of elute was performed using PDA detector at 305 nm. Mifepristone was eluted at 8.67 min. According to international conference on harmonization Q2(R1) guideline, method was validated and shows satisfactory results for accuracy, precision, linearity, ruggedness, robustness, detection limit, quantitation limit. The method indicated to be linear in the series of concentration 3–18 µg mL−1, and correlation coefficient was 0.9997. In acidic, basic, oxidative, thermal, photolytic forced degradation conditions, the peak of degradation product was clearly and well separated from drug peak without any interference in quantitative analysis. This represents stability indicating nature of established method.

Conclusion

The established RP-HPLC method is simple, accurate, specific, precise, robust, rugged, sensitive, and economical in nature which can be utilized for routine analysis of mifepristone in bulk and pharmaceutical formulation.

Development of a xylosyltransferase-I-selective UPLC MS/MS activity assay using a specific acceptor peptide

Xylosyltransferases-I and -II (XT-I and -II) play an important role regarding the homeostasis of the extracellular matrix. Both enzymes catalyze the initial step of the proteoglycan (PG) biosynthesis by the transfer of xylose from their natural substrate uridine diphosphate (UDP) -xylose to a PG-core protein. The subsequent addition of further sugars, catalyzed by different glycosyltransferases, leads to the formation of a tetrasaccharide linker, which connects the PG-core protein and glycosaminoglycans. The reason for the appearance of two XT isoforms in all higher organisms is not known and remarkable, as both enzymes are able to initiate PG biosynthesis. The determination of the XT-I activity is of clinical importance because it can be used as a biomarker of several PG-associated fibrotic diseases. Since previous assays did not adequately differentiate between both XT-isoforms, the aim of this study was to develop an XT-I selective mass spectrometric (MS) assay. For this purpose, we initially used isoform-specific supernatants to successfully identify a synthetic acceptor peptide which was xylosylated much more selectively by the XT-I when compared to the XT-II isoform. The assay was further optimized concerning methodical parameters such as the injection volume and the incubation time of the reaction-mixture. By using samples covering a broad XT-activity spectrum, we successfully validated the assay to be used not only for the quantification of cell culture samples but also human serum specimens. Compared to previously used XT-activity assays, our newly developed test is more selective and sensitive, less expensive and easier to perform in high throughput.

Determination of cymipristone in human plasma by liquid chromatography-electrospray ionization-tandem mass spectrometry

A rapid, specific and sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry method was developed and validated for determination of cymipristone in human plasma. Mifepristone was used as the internal standard (IS). Plasma samples were deproteinized using methanol. The compounds were separated on a ZORBAX SB C(18) column (50 mm x 2.1 mm i.d., dp 1.8 microm) with gradient elution at a flow-rate of 0.3 ml/min. The mobile phase consisted of 10 mM ammonium acetate and acetonitrile. The detection was performed on a triple-quadruple tandem mass spectrometer by selective reaction monitoring (SRM) mode via electrospray ionization. Target ions were monitored at [M+H](+)m/z 498-->416 and 430-->372 in positive electrospray ionization (ESI) mode for cymipristone and IS, respectively. Linearity was established for the range of concentrations 0.5-100 ng/ml with a coefficient correlation (r) of 0.9996. The lower limit of quantification (LLOQ) was identifiable and reproducible at 0.5 ng/ml. The validated method was successfully applied to study the pharmacokinetics of cymipristone in healthy Chinese female subjects.

Mineralocorticoid and Glucocorticoid Receptors Stimulate Epithelial Sodium Channel Activity in a Mouse Model of Cushing Syndrome

Experiments in Cushing patients and healthy control subjects receiving adrenocorticotropic hormone (ACTH) indicate that transient renal sodium retention may contribute to the generation of hypertension. Here we have investigated the effect of chronic ACTH infusion on renal sodium handling in adult male C57BL/6J mice using selective antagonists to dissect mineralocorticoid and glucocorticoid receptor–mediated pathways. Mice were infused via osmotic minipump with ACTH (2.5 μg/d) or saline for 2 weeks before being anesthetized for renal function experiments. ACTH caused an increase in blood pressure and a reduction in fractional sodium excretion associated with enhanced activity of the epithelial sodium channel. Given separately, spironolactone and RU38486 blunted the pressor response to ACTH and the increased epithelial sodium channel activity; combined mineralocorticoid and glucocorticoid receptor blockade was required to resolve the response to ACTH excess. Dietary sodium depletion also prevented ACTH-induced hypertension. The effect of increased sodium reabsorption in the distal nephron is offset by downregulation of Na-K-Cl cotransport in the loop of Henle. Sodium excretion is normalized chronically, but blood pressure remains high; acute blockade of V1 receptors and α1 adrenoceptors in combination restored blood pressure to control values. In summary, ACTH excess promotes renal sodium reabsorption, contributing to the increased blood pressure; both glucocorticoid and mineralocorticoid receptor pathways are involved. These data are relevant to conditions associated with overactivity of the hypothalamic-pituitary-adrenal axis, such as obesity and chronic stress.

Combined receptor antagonist stimulation of the hypothalamic-pituitary-adrenal axis test identifies impaired negative feedback sensitivity to cortisol in obese men

CONTEXT

Hypothalamic-pituitary-adrenal (HPA) axis dysregulation may underlie disorders including obesity, depression, cognitive decline, and the metabolic syndrome. Conventional tests of HPA axis negative feedback rely on glucocorticoid receptor (GR) agonists such as dexamethasone but do not test feedback by endogenous cortisol, potentially mediated by both GR and mineralocorticoid receptors (MR).

OBJECTIVE

The objective of the study was to use a combination of GR (RU38486, mifepristone) and MR (spironolactone) antagonists to explore the poorly understood activation of the HPA axis that occurs in obesity.

DESIGN

This was a double-blind, placebo-controlled, randomized, crossover study.

SETTING

The study was conducted at a clinical research facility.

PARTICIPANTS

Participants included 15 lean (body mass index 22.0 +/- 1.6 kg/m(2)) and 16 overweight/obese (body mass index 30.1 +/- 3.5 kg/m(2)) men.

INTERVENTION

Subjects attended on four occasions for blood and saliva sampling every 30 min between 1800 and 2200 h. At 1100 and 1600 h before visits, subjects took 200 mg spironolactone, 400 mg RU38486, 200 mg spironolactone + 400 mg RU38486, or placebo orally.

MAIN OUTCOME MEASURES

Serum cortisol levels after drug or placebo were measured.

RESULTS

Cortisol levels did not differ between lean and obese after placebo. Spironolactone and RU38486 alone had modest effects, increasing cortisol by less than 50% in both groups. However, combined spironolactone plus RU38486 elevated cortisol concentrations substantially, more so in lean than obese men [2.9- (0.3) vs. 2.2 (0.3)-fold elevation, P = 0.002].

CONCLUSIONS

Combined receptor antagonist stimulation of the HPA axis reveals redundancy of MR and GR in negative feedback in humans. Obese men have impaired responses to combined receptor antagonist stimulation, suggesting impaired negative feedback by endogenous cortisol. Such an approach may be useful to dissect abnormal HPA axis control in neuropsychiatric and other disorders.