Disposition and sterol-lowering effect of ezetimibe in multidrug resistance-associated protein 2-deficient rats.
Disposition of the lipid-lowering agent ezetimibe (EZ) and its glucuronide (GLUC), which is mainly formed by UDP-glucuronosyltransferase (UGT) 1A1, is influenced by the intestinal efflux transporters P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) 2. To evaluate the role of Mrp2 in overall disposition and pharmacodynamic effects of EZ, wild-type and Mrp2-deficient (TR-negative) Lewis.1W rats (eight males each) fed with a cholesterol-enriched diet were orally treated with 5 mg/kg EZ for 14 days. EZ and GLUC in serum, urine, and feces, and cholesterol, campesterol, and sitosterol in serum, were assayed using liquid chromatography (LC)-tandem mass spectrometry and LC-mass spectrometry methods, respectively. Gene expression of Bsep (bile salt exporting pump), multidrug resistance (Mdr) 1a, Mdr1b, Mrp2, Mrp3, Ntcp (sodium taurocholate co-transporting polypeptide), organic anion transporting polypeptides (Oatp) 1, 2, 4, and Ugt1a1 was quantified in several tissues using real-time reverse transcription-polymerase chain reaction. Mrp2 deficiency resulted in lower serum levels and fecal excretion of EZ (1.4 +/- 0.4 versus 3.1 +/- 1.1 ng/ml; 115 +/- 48 versus 361 +/- 102 microg/day, both p < 0.01), whereas serum concentrations of GLUC were manyfold increased compared with wild type (196 +/- 76 versus 23 +/- 25 ng/ml; p < 0.01), associated with elevated renal excretion and decreased intestinal clearance (7.8 +/- 3.1 versus 0.4 +/- 0.4 microg/day, p < 0.01; 0.3 +/- 0.3 versus 15 +/- 17 ml/min; p < 0.05). The sterol-lowering effect of EZ was reduced in correlation to EZ serum levels (cholesterol: r = 0.449, p = 0.093; campesterol: r = 0.717, p = 0.003; sitosterol: r = 0.507, p = 0.054), whereas GLUC was inversely correlated (r = -0.743, p = 0.002; r =-0.768, p = 0.001; r =-0.634, p = 0.011). Disposition of EZ may have been additionally influenced by hepatic P-gp, Mrp3, and Ugt1a1, which were expressed significantly higher in Mrp2-deficient rats. Mrp2 deficiency in rats is associated with decreased sterol-lowering effect of ezetimibe, obviously caused by lower intestinal clearance of the glucuronide and decreased enterosystemic and enterohepatic recycling of the parent ezetimibe to the intestinal Niemann-Pick C 1-like 1 sterol-uptake compartment.
Oswald
Stefan
S
Department of Clinical Pharmacology, University of Greifswald, Germany. stefan.oswald@uni-greifswald.de
Westrup
Sabine
S
Grube
Markus
M
Kroemer
Heyo K
HK
Weitschies
Werner
W
Siegmund
Werner
W
D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D001384:Azetidines / Q000493:pharmacokinetics / Q000494:pharmacology*; D002784:Cholesterol / Q000097:blood; D000069438:Ezetimibe; D014453:Glucuronosyltransferase / Q000235:genetics; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics / Q000502:physiology*; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000502:physiology*; D010840:Phytosterols / Q000097:blood; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011917:Rats, Inbred Lew; D000099148:UGT1A1 Enzyme
D000924:Anticholesteremic Agents; D001384:Azetidines; D002784:Cholesterol; D000069438:Ezetimibe; D014453:Glucuronosyltransferase; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010840:Phytosterols; D012333:RNA, Messenger; C482444:NPC1L1 protein, rat; C499946:Ugt1a1 protein, rat; D000099148:UGT1A1 Enzyme