Simple and sensitive high-performance liquid chromatography method for simultaneous determination of urinary free cortisol and 6beta-hydroxycortisol in routine practice. For CYP 3A4 activity evaluation in basal conditions and after grapefruit juice intake

High-performance liquid chromatography methods for the analysis of endogenous cortisol and cortisone in human urine: comparison of mass spectrometry and fluorescence detection

BACKGROUND

The analysis of steroids in biological matrices is challenging. One can apply immunoassay as well as gas and liquid chromatography with various types of detection, depending on the available equipment and the experience of the analyst. The question is how the methods are interchangeable between themselves. Doubts were reported having compared immunoassays and chromatography-mass spectrometry, but there are scarce data on chromatographic methods with detection types other than mass spectrometry.

METHODS

Here, we present the detailed comparison of two liquid chromatographic methods for the determination of free urinary cortisol and cortisone: one with fluorescence detection (high-performance liquid chromatography [HPLC-FLD]) and the other with tandem mass spectrometry (HPLC-MS/MS). The comparison was made with 199 human urine samples. The data analysis included Passing-Bablok and Deming regression, Bland-Altman test, Wilcoxon test, mountain plot and Lin's concordance correlation coefficient.

RESULTS

The validation data indicated that both methods met the requirements of the European Medicines Agency. However, the statistical analysis revealed the systematic bias between the two assays. The Passing-Bablok and the Deming tests showed that the HPLC-FLD method overestimated results for cortisol and underestimated measurements for cortisone. The Bland-Altman analysis estimated the mean differences between the methods: 18.8 nmol/L for cortisol and -16.9 nmol/L for cortisone measurement.

CONCLUSIONS

Both methods' results led to the same conclusion in observational studies, but the techniques are not interchangeable. The literature data, the observations from the clinical setting and our experience clearly indicate that the future of steroid measurements will belong to chromatography coupled with mass spectrometry.

Effects of grapefruit juice on cortisol metabolism in healthy male Chinese subjects

Grapefruit juice (GFJ) inhibits intestinal CYP3A4 activity and it has been suggested that GFJ may also inhibit renal 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), which converts cortisol to cortisone. This study examined the effect of GFJ on the urinary excretion of cortisol, cortisone and 6β-hydroxycortisol (6β-OHC) and their ratios to asses these effects. Healthy male Chinese subjects took single doses of GFJ (200, 400, and 600 mL, respectively) at weekly intervals. Urine was collected over 24 h the day before and following GFJ intake. Subsequently, volunteers drank 400 mL GFJ for 7 days and urine was collected from 0 to 4 h daily. GFJ had dose-dependent effects on increasing cortisol excretion (P <0.05) and the ratio of cortisol to cortisone (P <0.005) and reducing 6β-OHC excretion (P <0.05) and the ratio of 6β-OHC to cortisol (P <0.005). There was no significant effect on cortisone excretion. Maximal effects were observed within 4 h after GFJ ingestion. Repeated doses had persistent but no cumulative effects. GFJ significantly reduced the ratio of 6β-OHC to cortisol. It increased the ratio of cortisol to cortisone and this appeared largely due to increased cortisol excretion related to impaired CYP3A4-mediated cortisol metabolism although a true inhibitory effect on 11β-HSD2 in the kidney cannot be excluded.

Optimization of a pre-MEKC separation SPE procedure for steroid molecules in human urine samples

Many steroid hormones can be considered as potential biomarkers and their determination in body fluids can create opportunities for the rapid diagnosis of many diseases and disorders of the human body. Most existing methods for the determination of steroids are usually time- and labor-consuming and quite costly. Therefore, the aim of analytical laboratories is to develop a new, relatively low-cost and rapid implementation methodology for their determination in biological samples. Due to the fact that there is little literature data on concentrations of steroid hormones in urine samples, we have made attempts at the electrophoretic determination of these compounds. For this purpose, an extraction procedure for the optimized separation and simultaneous determination of seven steroid hormones in urine samples has been investigated. The isolation of analytes from biological samples was performed by liquid-liquid extraction (LLE) with dichloromethane and compared to solid phase extraction (SPE) with C18 and hydrophilic-lipophilic balance (HLB) columns. To separate all the analytes a micellar electrokinetic capillary chromatography (MECK) technique was employed. For full separation of all the analytes a running buffer (pH 9.2), composed of 10 mM sodium tetraborate decahydrate (borax), 50 mM sodium dodecyl sulfate (SDS), and 10% methanol was selected. The methodology developed in this work for the determination of steroid hormones meets all the requirements of analytical methods. The applicability of the method has been confirmed for the analysis of urine samples collected from volunteers--both men and women (students, amateur bodybuilders, using and not applying steroid doping). The data obtained during this work can be successfully used for further research on the determination of steroid hormones in urine samples.

HPLC method for determination of fluorescence derivatives of cortisol, cortisone and their tetrahydro- and allo-tetrahydro-metabolites in biological fluids

11Beta-hydroxysteroid dehydrogenase isoform 2 (11beta-HSD2) is responsible for conversion of cortisol (F) to inactive cortisone (E). Disturbance of its activity can cause hypertension. To estimate 11beta-HSD2 activity, besides F and E, their tetrahydro- (THF, THE) as well allo-tetrahydro- (allo-THF, allo-THE) metabolites should be determined. This study describes HPLC-FLD method for the quantitative determination of endogenous glucocorticoids (GCs) in plasma and urine (total and free) and their metabolites in urine. Following extraction at pH 7.4 using dichloromethane, GCs (F, E, THF, allo-THF, THE, allo-THE and internal standard--prednisolone) were derivatized with 9-anthroyl nitrile and purified by SPE using C(18) cartridges. The enzymatic hydrolysis of conjugated steroids was provided using beta-glucuronidase. The influence of organic bases on 9-AN derivatization of steroids was investigated. The best yield of the derivatization was obtained in presence of the mixture of 10.0% triethylamine (TEA) and 0.1% quinuclidine (Q). Chromatographic separation was accomplished in the Chromolith RP-18e monolithic column. The elaborated method was validated. Calibration curves were linear in the ranges: for F, E and THF 5.0-1000.0 ng mL(-1), for allo-THF and THE + allo-THE 10.0-1000.0 ng mL(-1). LOD (S/N=3:1) for all analytes amounted 3.0 ng mL(-1). Recoveries of GCs exceeded 90%. The method was precise and accurate, intra- and inter-day precision were 3.0-12.1% and 9.2-14.0%, respectively. Accuracy ranged from 0.2 to 15.1%. The method was applied for estimating endogenous GCs in plasma and urine. Plasma levels of F and E were in the ranges: 133.0-174.5 ng mL(-1) and 17.4-35.9 ng mL(-1), respectively. Free urinary steroids were in the ranges: 12.0-54.1 microg/24 h (UFF) and 37.8-76.2 microg/24 h (UFE). The ratio of (THF + allo-THF)/(THE + allo-THE) amounted from 1.01 to 1.23. The obtained results confirmed utility of the elaborated method in the assessment of 11beta-HSD2 activity in man.

Pharmacokinetic and pharmacogenetic determinants of the activity and toxicity of irinotecan in metastatic colorectal cancer patients

This study aims at establishing relationships between genetic and non-genetic factors of variation of the pharmacokinetics of irinotecan and its metabolites; and also at establishing relationships between the pharmacokinetic or metabolic parameters and the efficacy and toxicity of irinotecan. We included 49 patients treated for metastatic colorectal cancer with a combination of 5-fluorouracil and irinotecan; a polymorphism in the UGT1A1 gene (TA repeat in the TATA box) and one in the CES2 gene promoter (830C>G) were studied as potential markers for SN-38 glucuronidation and irinotecan activation, respectively; and the potential activity of CYP3A4 was estimated from cortisol biotransformation into 6β-hydroxycortisol. No pharmacokinetic parameter was directly predictive of clinical outcome or toxicity. The AUCs of three important metabolites of irinotecan, SN-38, SN-38 glucuronide and APC, were tentatively correlated with patients' pretreatment biological parameters related to drug metabolism (plasma creatinine, bilirubin and liver enzymes, and blood leukocytes). SN-38 AUC was significantly correlated with blood leukocytes number and SN-38G AUC was significantly correlated with plasma creatinine, whereas APC AUC was significantly correlated with plasma liver enzymes. The relative extent of irinotecan activation was inversely correlated with SN-38 glucuronidation. The TATA box polymorphism of UGT1A1 was significantly associated with plasma bilirubin levels and behaved as a significant predictor for neutropoenia. The level of cortisol 6β-hydroxylation predicted for the occurrence of diarrhoea. All these observations may improve the routine use of irinotecan in colorectal cancer patients. UGT1A1 genotyping plus cortisol 6β-hydroxylation determination could help to determine the optimal dose of irinotecan.

Ile118Val genetic polymorphism of CYP3A4 and its effects on lipid-lowering efficacy of simvastatin in Chinese hyperlipidemic patients

OBJECTIVES

To determine the frequencies of CYP3A4 alleles (CYP3A4*4,*5 and *6) in Chinese hyperlipidemic patients and to observe the impact of CYP3A4*4 (Ile118Val) genetic polymorphism on the lipid-lowering effects of simvastatin and on the activity of CYP3A4.

METHODS

From hospitalized and non-hospitalized patients, 211 unrelated hyperlipidemic patients were recruited for genotyping. CYP3A4 genotypes were determined by means of polymerase chain reaction and restriction fragment length polymorphism analysis. Of the non-hospitalized hyperlipidemic patients, 8 with CYP3A4*1/*1 and 8 with CYP3A4*1/*4 genotypes were selected to be treated with 20 mg simvastatin daily for 4 weeks. Serum triglycerides (TG), cholesterol (CHO) and low-density lipoprotein (LDL) levels were determined using an automated analyzer (Hitachi 747, Boehringer Mannheim, Mannheim, Germany). CYP3A4 activity was determined by the ratio of 6-hydroxycortisol to free cortisol (6-OHC/FC) in the morning spot urine with a high-throughput liquid chromatography-tandem mass spectrometry method.

RESULTS

Of 211 subjects, 14 (allele frequency 3.32%) were heterozygous for CYP3A4*4 (Ile118Val). Nevertheless, no subjects with a CYP3A4*5 or CYP3A4*6 allele or homozygous for CYP3A4*4 were identified. The ratio of 6beta-OHC/FC was 9.9 +/- 13.7 and 56.6 +/- 35.7 in subjects with the Ile118Val variant (n = 8) and in CYP3A4 wild-type subjects (n = 8), respectively (P = 0.0039). After oral intake of simvastatin 20 mg daily for 4 weeks, the change of serum lipids in CYP3A4*1/*1 and CYP3A4*1/*4 groups showed a significant difference, with a mean decrease in triglycerides and total cholesterol of 38.1 +/- 7.6% versus 25.1 +/- 8.3% (P = 0.034) and of 35.8 +/- 9.6% versus 22.0 +/-20.4% (P = 0.0015) (means +/- SD), respectively. We found no statistically significant difference in the reductions of LDL between subjects carrying the *1 and *4 genotypes (29.0 +/- 7.4% versus 36.8 +/- 8.8%, P = 0.0721).

CONCLUSIONS

The allele frequency of CYP3A4*4 was 3.32% among the hyperlipidemic patients from the Chinese mainland. CYP3A4*4 was an allelic variant related to a functional decrease of CYP3A4 activity, and *4 expression seemed to increase the lipid-lowering effects of simvastatin.