Urinary 6β-Hydroxycortisol/Cortisol Ratio Most Highly Correlates With Midazolam Clearance Under Hepatic CYP3A Inhibition and Induction in Females: A Pharmacometabolomics Approach

Abstract

Endogenous metabolites of cytochrome P450 (CYP3A) are useful in predicting drug-drug interactions between in vivo CYP3A inhibitors and inducers for clinical applications of CYP3A substrate drugs. This study aimed to develop predictable markers of the magnitude of hepatic CYP3A induction and inhibition in healthy female subjects using pharmacometabolomics. Twelve female subjects received midazolam during three study phases: 1 mg midazolam (control phase), 1 mg midazolam after pretreatment with 400 mg ketoconazole once daily for 4 days (CYP3A inhibition phase), and 2.5 mg midazolam after pretreatment with 600 mg rifampicin once daily for 10 days (CYP3A induction phase). Throughout the study, blood samples were collected 24 h after midazolam administration and urine samples at 12-h intervals during the 24 h before and after midazolam administration for the analysis of endogenous steroid metabolites. A statistical model was generated to predict midazolam clearance using measurements of endogenous metabolites associated with the inhibition and induction of CYP3A. Mean midazolam clearance decreased to ∼20% of control levels during the inhibition phase and increased more than 2-fold during the induction phase. Of the urine and plasma metabolites measured, the 6β-hydroxycortisol/cortisol ratio was most significantly correlated with midazolam clearance during hepatic CYP3A inhibition and induction. Our results suggest that the urinary 6β-hydroxycortisol/cortisol ratio is the best predictor of hepatic CYP3A activity under both maximal inhibition and maximal induction. Furthermore, the predictive model including 6β-hydroxycortisol/cortisol as a covariate could be applied to predict the magnitude of CYP3A-mediated drug interactions.

Identification of ω‐ or (ω‐1)‐Hydroxylated Medium‐Chain Acylcarnitines as Novel Urinary Biomarkers for CYP3A Activity

“…Consistent with our previously reported models for predicting midazolam clearance using steroid markers, urinary 6β‐OH cortisol was selected as a CYP3A marker in the final model, showing a strong correlation with midazolam clearance ( r = 0.772). Along with 6β‐OH cortisol, the novel three hydroxy acylcarnitine CYP3A markers as covariates in our model reflected the extent of CYP3A activity in both genders, with high predictability ( r 2 = 0.894).…”

“…Elevations of hydroxy testosterone sulfate and hydroxy androsterone sulfate have been observed following rifampicin administration . Furthermore, significant changes in urinary metabolites and metabolite ratio of 16α‐hydroxy testosterone and 16α‐hydroxy testosterone/testosterone have been observed in the CYP3A‐inhibited phase as compared to the control phase. In contrast, 16α‐hydroxy testosterone/testosterone was not significantly changed in the CYP3A‐induced phase as compared to the control phase, but 16α‐OH TS was significantly altered by both CYP3A inhibition and induction in this study, which means that sulfotransferase (SULT) 2A1, in addition to CYP3A, contributes to the metabolism of testosterone.…”

“…To avoid unnecessary drug exposure and invasive sampling, evaluating an individual's CYP3A phenotype through measurement of sensitive endogenous biomarkers, especially urinary compounds, would be ideal. Urinary 6β‐hydroxycortisol‐to‐cortisol and 6β‐hydroxycortisone‐to‐cortisone ratios have been suggested as endogenous CYP3A markers and reportedly highly correlate with midazolam clearance in vivo . Plasma 4β‐hydroxycholesterol has also been evaluated as a surrogate for midazolam pharmacokinetics (PK) .…”

“…To date, CYP3A biomarkers have been evaluated only by targeted metabolomics. Using targeted steroid profiling, we previously reported models for predicting midazolam clearance based on 7β‐OH DHEA/DHEA, 6β‐OH cortisol/cortisol, and 6β‐OH cortisone/cortisone in male and female subjects. Furthermore, we validated major steroid markers and developed the model in various sex‐ and age‐stratified groups at the basal state …”

CYP3A and CYP2C19 activity in urine in relation to CYP3A4, CYP3A5, and CYP2C19 polymorphisms in Russian peptic ulcer patients taking omeprazole

“… 6 CYP3A4 activity may be detected using 6β-hydroxycortisol/cortisol ratios in urine. 7 CYP3A4 genetic polymorphisms are being studied. CYP3A4*22, found in 2011, is associated with low CYP3A4 expression and low CYP3A4 activity.…”