Optical Isomers of Atorvastatin, Rosuvastatin and Fluvastatin Enantiospecifically Activate Pregnane X Receptor PXR and Induce CYP2A6, CYP2B6 and CYP3A4 in Human Hepatocytes.

Martina Korhonova,Aneta Doricakova,Zdenek Dvorak,Hans-Joachim Lehmler

doi:10.1371/journal.pone.0137720

Abstract

Atorvastatin, fluvastatin and rosuvastatin are drugs used for treatment of hypercholesterolemia. They cause numerous drug-drug interactions by inhibiting and inducing drug-metabolizing cytochromes P450. These three statins exist in four optical forms, but they are currently used as enantiopure drugs, i.e., only one single enantiomer. There are numerous evidences that efficacy, adverse effects and toxicity of drugs may be enantiospecific. Therefore, we investigated the effects of optical isomers of atorvastatin, fluvastatin and rosuvastatin on the expression of drug-metabolizing P450s in primary human hepatocytes, using western blots and RT-PCR for measurement of proteins and mRNAs, respectively. The activity of P450 transcriptional regulators, including pregnane X receptor (PXR), aryl hydrocarbon receptor (AhR) and glucocorticoid receptor (GR), was assessed by gene reporter assays and EMSA. Transcriptional activity of AhR was not influenced by any statin tested. Basal transcriptional activity of GR was not affected by tested statins, but dexamethasone-inducible activity of GR was dose-dependently and enantioselectively inhibited by fluvastatin. Basal and ligand-inducible transcriptional activity of PXR was dose-dependently influenced by all tested statins, and the potency and efficacy between individual optical isomers varied depending on statin and optical isomer. The expression of CYP1A1 and CYP1A2 in human hepatocytes was not influenced by tested statins. All statins induced CYP2A6, CYP2B6 and CYP3A4, and the effects on CYP2C9 were rather modulatory. The effects varied between statins and enantiomers and induction potency decreased in order: atorvastatin (RR>RS = SR>SS) > fluvastatin (SR>RS = SS>RR) >> rosuvastatin (only RS active). The data presented here might be of toxicological and clinical importance.

Highlights

Statins are a class of drugs used for the treatment of hypercholesterolemia, a major risk factor for the development of atherosclerotic disease
The cells were incubated for 24 h with individual enantiomers of atorvastatin, fluvastatin and rosuvastatin at concentrations ranging from 100 pM to 100 μM
Based on the results from cytotoxicity testing (Fig 2), gene reporter assays were performed in concentrations of tested compounds up to 100 μM, with exception of atorvastatin, where maximal concentration of 10 μM was used for incubations in AZ-AHR and AZ-glucocorticoid receptor (GR) cells

Summary

Introduction

Statins are a class of drugs used for the treatment of hypercholesterolemia, a major risk factor for the development of atherosclerotic disease. Statins are chiral compounds having two asymmetrical centres in the molecule, enabling formation of four different enantiomers: 3R5R, 3R5S, 3S5R and 3S5S (Fig 1). Individual enantiomers of a drug can qualitatively and quantitatively differ in their biological activities, including their pharmacokinetics, pharmacodynamics, toxicokinetics and toxicodynamics. Known examples of diastereomers with substantially different biologial activities are R/S-thalidomide, R/S-salbutamol, levo/dextro-methorphan and many others [1]. Enantiopure drugs have been developed and introduced to the therapy. Regarding the most frequently prescribed statins, following enantiopure formulations are used in the clinics: 3R5R-atorvastatin (Lipitor, Pfizer; since Nov 2011 generic), 3R5S-rosuvastatin (Crestor, AstraZeneca; approved 12th Aug 2003) and 3R5S-fluvastatin (Lescol, Novartis; approved 31st Dec 1993; since 2011 generic)

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