Increase in urinary excretion of 6beta-hydroxycortisol in common marmosets as a marker of hepatic CYP3A induction

Effects of Plasmodium falciparum infection on the pharmacokinetics of quinine and its metabolites in pregnant and non-pregnant Sudanese women

PURPOSE

The study aimed to investigate the effects of Plasmodium falciparum infection on the pharmacokinetics of quinine and its metabolites in pregnant and non-pregnant Sudanese women.

METHODS

In a case-control study, nine pregnant and eight non-pregnant Sudanese women infected with P. falciparum were treated with intramuscular artemether. Before being given artemether, they received a single dose of quinine hydrochloride as intravenous infusion. Blood samples were collected frequently and analysed for quinine and its metabolites (phase I). One week later (after clearance of parasitaemia) the quinine part of the protocol was repeated (phase II).

RESULTS

During phase I, the AUCs (mean ± SD) of quinine and its major metaboplite, 3-hydroxyquinine, in pregnant women were 428.2 ± 132.4 and 27.8 ± 14.1 μmol l(-1) h(-1) respectively. In non-pregnant women the AUCs of quinine and 3-hydroxyquinine were 517.8 ± 100.0 and 32.3 ± 15.3 μmol l(-1) h(-1). In pregnant women the mean (90% confidence interval) AUC ratios of phase I to phase II of quinine and 3-hydroxyquinine were 1.6 (0.61, 4.22) and 1.01 (0.18, 5.60). In non-pregnant women, the AUC ratios of phase I to phase II of quinine and 3-hydroxyquinine were 1.93 (1.74, 2.15) and 1.19 (0.95, 1.47).

CONCLUSIONS

Plasmodium falciparum infection significantly increased plasma concentration of quinine in non-pregnant women and showed the same trend in pregnant women.

Illicit treatments in cattle and urinary 6beta-hydroxycortisol/cortisol ratio

Dexamethasone (DXM) is often illegally used as a growth promoter. To identify indirect biomarkers of illicit treatments, the urinary ratio between 6beta-hydroxycortisol (6beta-OHF) and cortisol (F) was measured in urines obtained from bulls experimentally treated per os and intramuscularly (i.m.) with different DXM dosages. Dexamethasone, given per os at low doses elicited an early and lasting significant reduction of 6beta-OHF/F. No significant variations were seen in urines from bulls given DXM intramuscularly. These results suggest 6beta-OHF/F as a rapid, non-invasive, screening test for oral, low-dose, long-term corticosteroid treatment in cattle. Further studies are required to go deep inside the biochemical and molecular events underlying such an effect.

Comprehensive study of urinary cortisol metabolites in hyperthyroid and hypothyroid patients

OBJECTIVE

To further analyse the significance and mutual relationship of thyroid function-linked alterations in cortisol metabolism that have been separately and variously reported.

PATIENTS AND MEASUREMENTS

Twenty-four-hour urine samples from 21 patients with hyperthyroidism (Graves' disease), 16 patients with hypothyroidism (Hashimoto's thyroiditis), 21 healthy age- and sex-matched controls for hyperthyroidism, and 16 healthy age- and sex-matched controls for hypothyroidism were evaluated for 6beta-hydroxycortisol (6beta-OHF), tetrahydrocortisol (THF), tetrahydrocortisone (THE), allo-tetrahydrocortisol (allo-THF), urinary free cortisol (UFF), urinary free cortisone (UFE) and 17-hydroxycorticosteroid (17-OHCS).

RESULTS

Urinary 17-OHCS, THE and allo-THF levels increased considerably in hyperthyroid patients compared to the controls, while UFF and THF showed no difference between the two groups. Urinary 6beta-OHF was significantly lower in the hyperthyroid patients than in the controls. Both the urinary allo-THF + THF/THE and the UFF/UFE ratios were significantly lower in the hyperthyroid patients than in the controls, whereas only the former was significantly higher in the hypothyroid patients than in the controls. The urinary allo-THF/THF ratio was significantly higher in the hyperthyroid patients and significantly lower in the hypothyroid patients than in the controls. In an analysis of pooled subjects including all groups (n = 64), free T4 levels correlated negatively (P < 0.0001) with the urinary allo-THF + THF/THE ratio but not with the UFF/UFE ratio. The serum levels of free T4 correlated positively (P < 0.0001) with the urinary allo-THF/THF ratio.

CONCLUSION

The thyroid hormones seem to affect the total 11beta-HSD activity (allo-THF + THF/THE) more strongly than the renal 11beta-HSD2 activity (UFF/UFE). 5alpha-reductase activity (allo-THF/THF) is also enhanced in hyperthyroidism, while the reduction of urinary 6beta-OHF in hyperthyroidism might be a secondary effect of the altered activity of the total 11beta-HSD and 5alpha-reductase.

DEET (N,N-diethyl-m-toluamide) alone and in combination with permethrin increased urinary excretion of 6beta-hydroxycortisol in rats, a marker of hepatic CYP3A induction

In this study, the ratio of 6beta-hydroxycortisol (6beta-OHF) to free cortisol (F) was determined in urine following a single dermal dose of 400 mg/kg of DEET (N,N-diethyl-m-toluamide), and 1.3 mg/kg of permethrin, alone and in combination, in rats. Urine samples were collected at 2, 4, 8, 16, 24, 48, and 72 h after application. Recoveries of 6beta-OHF and cortisol (F) from control urine samples were between 75 and 85%, with limits of detection at 30 and 10 ng/ml for cortisol and 6beta-OHF, respectively. A single dermal dose of DEET alone and in combination with permethrin significantly increased urinary excretion of 6beta-hydroxycortisol 24 h after dosing. Permethrin did not significantly alter the urinary excretion of 6beta-hydroxycortisol. These results indicate that DEET, alone and in combination with permethrin, increased urinary excretion of 6beta-OHF in rats following a single dermal dose application.

Simultaneous determination of urinary free cortisol and 6beta-hydroxycortisol by liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry and its application for estimating hepatic CYP3A induction

A reversed-phase high-performance liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry (HPLC-APCI-MS-MS) assay was developed to simultaneously determine monkey urinary free cortisol (C) and 6beta-hydroxycortisol (6beta-OHC) in 8 min. Urine sample (0.5 ml) containing fludrocortisone acetate (F-C) as the internal standard was extracted with ethyl acetate for 5 min with an extraction efficiency of 90% and 75% for C and 6beta-OHC, respectively. A Perkin-Elmer Sciex API 3000 triple quadruple instrument was used for mass spectrometric detection and the column eluent was directed to a heated nebulizer probe. The assay was linear over the range 0.25-10 microM for each analyte. The intra- and inter-day relative standard deviation (RSD) over the entire concentration range for both analytes was less than 10%. Accuracy determined at three concentrations (0.8, 2.0 and 8.0 microM) ranged between 95.5 and 108%. The method described herein is suitable for the rapid and efficient measurement of 6beta-OHC/C ratio in Rhesus monkey urine following administration of known hepatic CYP3A inducers and can be used to estimate potential CYP3A induction by drug candidates in the process of early drug development.