Evaluation of 1β-Hydroxylation of Deoxycholic Acid as a Non-Invasive Urinary Biomarker of CYP3A Activity in the Assessment of Inhibition-Based Drug-Drug Interaction in Healthy Volunteers.

Xue-Qing Li,Leif Bertilsson,Collen Masimirembwa,Tommy B Andersson,Roslyn Stella Thelingwani,Ulf Diczfalusy

doi:10.3390/jpm11060457

Abstract

In this study, we aimed to evaluate the utility of endogenous 1β-hydroxy-deoxycholic acid/total deoxycholic acid ratio (1β-OH-DCA/ToDCA) in spot urine as a surrogate marker of cytochrome P450 3A (CYP3A) activity in the assessment inhibition-based drug–drug interactions in healthy volunteers. This was accomplished through an open-label, three-treatment parallel-arm study in healthy male volunteers from Zimbabwe. Each group received itraconazole (ITZ; 100 mg once daily; n = 10), fluconazole (FKZ; 50 mg once daily; n = 9), or alprazolam (APZ; 1 mg once daily; n = 8) orally. Midazolam (MDZ), dosed orally and intravenously, was used as a comparator to validate the exploratory measures of CYP3A activity and the effects of known inhibitors. Urinary metabolic ratios of 1β-OH-DCA/ToDCA before and after CYP3A inhibitor treatment showed a similar magnitude of inhibitory effects of the three treatments as that measured by oral MDZ clearance. The maximum inhibition effect of a 75% reduction in the 1β-OH-DCA/ToDCA ratio compared to the baseline was achieved in the ITZ group following six once-daily doses of 100 mg. The correlations of the two markers for CYP3A inhibitor treatment were significant (rs = 0.53, p < 0.01). The half-life of urinary endogenous 1β-OH-DCA/ToDCA was estimated as four days. These results suggested that 1β-OH-DCA/ToDCA in spot urine is a promising convenient, non-invasive, sensitive, and relatively quickly responsive endogenous biomarker that can be used for CYP3A inhibition-based drug–drug interaction in clinical studies.

Highlights

The evaluation of the likelihood and magnitude of drug–drug interaction remains an integral part of drug candidate safety assessments during drug discovery, development, and regulatory review
This, involves the administration of probe drugs followed by invasive sampling. It might pose a risk for adverse effects and difficulty in conducting clinical drug–drug interaction (DDI) studies in patient populations
The baseline demographics of all male participants were balanced between the study arms (Table 1) with no statistically significant differences according to the Kruskal–Wallis test

Summary

Introduction

The evaluation of the likelihood and magnitude of drug–drug interaction remains an integral part of drug candidate safety assessments during drug discovery, development, and regulatory review. This, involves the administration of probe drugs followed by invasive sampling. It might pose a risk for adverse effects and difficulty in conducting clinical drug–drug interaction (DDI) studies in patient populations. Some endogenous compounds have been demonstrated to have potential as markers that mirror the interindividual variation of enzyme activities in drug metabolism [1,2,3].

Objectives

Methods

Results