Validation of 4β‐hydroxycholesterol and evaluation of other endogenous biomarkers for the assessment of CYP3A activity in healthy subjects

Abstract

AIMSThis study aimed to assess changes in the plasma concentrationss of 4β-hydroxycholesterol (4βHC) against intravenous (i.v.) and oral midazolam (MDZ) pharmacokinetics (PK) after administration of a potent CYP3A inhibitor [ketoconazole (KETO)] and inducer [rifampicin (RIF)]. METHODSThirty-two healthy subjects (HS) were allocated into three groups of 12 each in KETO and RIF and 10 in a placebo group (PLB). All HS were randomized to receive oral and i.v. MDZ on day 1 or 2 and on day 15 or 16 after receiving RIF (600 mg once daily), KETO (400 mg once daily) or PLB for 2 weeks. Subjects were followed until day 30. The effect of treatments on 4βHC was assessed by analyzing % change from baseline using a linear spline mixed effects model. RESULTSCompared with PLB, KETO decreased 4βHC mean values up to 13% (P = 0.003) and RIF increased 4βHC mean values up to 220% (P < 0.001). Within 14 days of stopping KETO and RIF, 4βHC had either returned to baseline (KETO) or was still returning to baseline (RIF). Compared with baseline, mean oral MDZ AUC increased by 11-fold (90% CI ranging from 9-fold to 13-fold increase) and decreased by 92% (90% CI ranging from 90% to 95% decrease) after KETO and RIF, respectively. Similar trends were observed for 6β-hydroxycortisol : cortisol (6βHCL : CL) urinary ratios. CONCLUSIONSChanges in plasma 4βHC can be utilized as a surrogate for MDZ PK after multiple doses of potent CYP3A inducers. There is a more limited dynamic range for 4βHC for assessment of potential CYP3A inhibitors. 4βHC is a valuable tool for the assessment of potential CYP3A inducers in early drug development. WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Endogenous plasma 4β-hydroxycholesterol (4βHC) concentrations have been used as a putative CYP3A activity marker. However, placebo controlled studies have not been conducted to assess the dynamic range of potent CYP3A inhibitors and inducers. WHAT THIS STUDY ADDS• This placebo-controlled study assessed the dynamic range of plasma 4βHC concentrations after administration of ketoconazole and rifampicin (for 14 days). A comparison is made with other CYP3A trait measures such as midazolam pharmacokinetics and putative endogenous CYP3A biomarkers. The time course of CYP3A activity before and after administration of CYP3A modulators is also examined. This study validates 4βHC against midazolam pharmacokinetics and also expands the utility of 4βHC to assess CYP3A activity after stopping treatment with CYP3A inducers or inhibitors.• Results from this study show utility of 4βHC to defer or avoid midazolam-based studies, saving cost and avoiding exposing healthy subjects to study medications.

miRNA‐27b levels are associated with CYP3A activity in vitro and in vivo

“…; Kasichayanula et al. ). Although the marker might be less suitable for monitoring inhibition of enzyme activity due to its long half‐life, we have shown that it is possible to detect strong inhibition of CYP3A if the inhibition last for at least 1 week (Lütjohann et al.…”

Coproporphyrins I and III as Functional Markers of OATP1B Activity: In Vitro and In Vivo Evaluation in Preclinical Species

“…Therefore, the availability of endogenous biomarkers to assess transporter activities during early drug development would have substantial benefits for the pharmaceutical industry in order to avoid expensive clinical trials and also minimize the risk of late-stage failures and even drug withdrawal. In this regard, many attempts have been made to identify endogenous compounds that could reflect the activities of enzymes and transporters, such as CYP3A4 (Kanebratt et al, 2008;Diczfalusy et al, 2011;Shin et al, 2013;Kasichayanula et al, 2014), CYP2D6 (Tay-Sontheimer et al, 2014), MATEs (Ito et al, 2012;Kato et al, 2014;Müller et al, 2015), and OAT3 (Imamura et al, 2014) to improve prediction of DDI. However, as far as we know, no validated in vivo clinical endogenous probe of OATP1B has been identified.…”

CYP3A Specifically Catalyzes 1 -Hydroxylation of Deoxycholic Acid: Characterization and Enzymatic Synthesis of a Potential Novel Urinary Biomarker for CYP3A Activity

“…A disadvantage of using 4b-hydroxycholesterol as a biomarker is the small dynamic range, which is affected by CYP3A inhibition. After 14 days of treatment by the strong CYP3A inhibitor ketoconazole, plasma 4b-hydroxycholesterol levels decreased by a maximum of 13%; oral midazolam levels increased 11-fold (Kasichayanula et al, 2014), highlighting the low dynamic range of this biomarker.…”