Intestinal expression of P-glycoprotein (ABCB1), multidrug resistance associated protein 2 (ABCC2), and uridine diphosphate-glucuronosyltransferase 1A1 predicts the disposition and modulates the effects of the cholesterol absorption inhibitor ezetimibe in humans.
OBJECTIVE
Ezetimibe is an inhibitor of the cholesterol uptake transporter Niemann-Pick C1-like protein (NPC1L1). Target concentrations can be influenced by intestinal uridine diphosphate-glucuronosyltransferases (UGTs) and the efflux transporters P-glycoprotein (P-gp) (ABCB1) and multidrug resistance associated protein 2 (MRP2) (ABCC2). This study evaluates the contribution of these factors to the disposition and cholesterol-lowering effect of ezetimibe before and after induction of UGT1A1, P-gp, and MRP2 with rifampin (INN, rifampicin).


METHODS
Serum concentrations of ezetimibe, as well as its glucuronide, and the plant sterols campesterol and sitosterol (surrogate for cholesterol absorption) were studied in 12 healthy subjects before and after rifampin comedication. In parallel, duodenal expression of UGT1A1, P-gp, MRP2, and NPC1L1 was quantified by use of real-time reverse transcriptase-polymerase chain reaction and quantitative immunohistochemical evaluation. The affinity of ezetimibe and its glucuronide to P-gp and MRP2 was assessed in P-gp- overexpressing Madin-Darby canine kidney II cells and P-gp-containing or MRP2-containing inside-out vesicles.


RESULTS
Up-regulation of intestinal P-gp, MRP2, and UGT1A1 (but not of NPC1L1) by rifampin was associated with markedly decreased areas under the curve of ezetimibe and its glucuronide (116 +/- 78.1 ng.h/mL versus 49.9 +/- 31.0 ng.h/mL and 635 +/- 302 ng.h/mL versus 225 +/- 86.4 ng.h/mL, respectively; both P = .002) and increased intestinal clearances (2400 +/- 1560 mL/min versus 5500 +/- 4610 mL/min [P = .003] and 76.6 +/- 113 mL/min versus 316 +/- 457 mL/min [P = .010], respectively) and nearly abolished sterol-lowering effects. Intestinal expression of UGT1A1, ABCB1, and ABCC2 was inversely correlated with the effects of ezetimibe on plant sterol serum concentrations. Parallel in vitro studies confirmed that ezetimibe glucuronide is a high-affinity substrate of MRP2 and has a low affinity to P-gp whereas ezetimibe interacts with P-gp and MRP2.


CONCLUSIONS
The disposition and sterol-lowering effects of ezetimibe are modified by metabolic degradation of the drug via intestinal UGT1A1 and either intestinal or hepatic secretion (or both) via P-gp and MRP2.
Oswald
Stefan
S
Department of Clinical Pharmacology, Peter Holtz Research Center of Pharmacology and Experimental Therapeutics, Greifswald, Germany.
Haenisch
Sierk
S
Fricke
Christiane
C
Sudhop
Thomas
T
Remmler
Cornelia
C
Giessmann
Thomas
T
Jedlitschky
Gabriele
G
Adam
Ulrike
U
Dazert
Eike
E
Warzok
Rolf
R
Wacke
Wolfram
W
Cascorbi
Ingolf
I
Kroemer
Heyo K
HK
Weitschies
Werner
W
von Bergmann
Klaus
K
Siegmund
Werner
W
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000235:genetics; D000328:Adult; D000904:Antibiotics, Antitubercular / Q000494:pharmacology; D000924:Anticholesteremic Agents / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001384:Azetidines / Q000493:pharmacokinetics*; D004347:Drug Interactions; D000069438:Ezetimibe; D005260:Female; D014453:Glucuronosyltransferase / Q000096:biosynthesis* / Q000235:genetics*; D006801:Humans; D007408:Intestinal Absorption / Q000235:genetics*; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000201:enzymology; D008297:Male; D026901:Membrane Transport Proteins / Q000096:biosynthesis* / Q000235:genetics*; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis* / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012293:Rifampin / Q000494:pharmacology; D013261:Sterols / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D000099148:UGT1A1 Enzyme
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000904:Antibiotics, Antitubercular; D000924:Anticholesteremic Agents; D001384:Azetidines; D000069438:Ezetimibe; D014453:Glucuronosyltransferase; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; D012293:Rifampin; D013261:Sterols; D000099148:UGT1A1 Enzyme; C000715087:ABCC2 protein, human