PT  - JOURNAL ARTICLE
AU  - Koji Kato
AU  - Yoshitaka Hasegawa
AU  - Katsuya Iwata
AU  - Takuya Ichikawa
AU  - Tohru Yahara
AU  - Satoshi Tsuji
AU  - Masayuki Sugiura
AU  - Jun-ichi Yamaguchi
TI  - Recommendation to Exclude Bile-Duct-Cannulated Rats with Hyperbilirubinemia for Proper Conduct of Biliary Drug Excretion Studies
AID  - 10.1124/dmd.116.070532
DP  - 2016 Aug 01
TA  - Drug Metabolism and Disposition
PG  - 1180--1183
VI  - 44
IP  - 8
4099  - http://dmd.aspetjournals.org/content/44/8/1180.short
4100  - http://dmd.aspetjournals.org/content/44/8/1180.full
SO  - Drug Metab Dispos2016 Aug 01; 44
AB  - Hyperbilirubinemia (HB) is sometimes encountered following bile-duct cannulation in rats. It possibly originates from the reduced functioning of multidrug resistance-associated protein 2 (Mrp2) and subsequent adaptive alterations in the expression of Mrp3 and the organic anion transporting polypeptides (Oatps). Our aim was to clarify the importance of excluding bile-duct-cannulated (BDC) rats with HB for proper conduct of drug excretion studies. We detected HB [serum total bilirubin concentration (TBIL) ≥0.20 mg/dl] in 16% of all BDC rats prepared. The serum activities of aspartate aminotransferase, alanine aminotransferase, leucine aminopeptidase, and alkaline phosphatase were within the respective normal ranges in the BDC rats with mild HB (TBIL, 0.20–0.79 mg/dl), indicating the absence of hepatic failure. In the pharmacokinetics of pravastatin, an Oatps/Mrp2 probe drug in the BDC rats, the apparent volume of distribution and the clearance were smaller in the mild HB group as compared with the normal group, suggesting the reduction of apparent hepatic uptake and hepatobiliary elimination. The biliary excretion (percentage of dose) was significantly reduced by 54%, suggesting that the biliary efflux activity via Mrp2 was reduced to a greater extent relative to metabolic activity in hepatocytes. The serum γ-glutamyltransferase (GGT) activity correlated with TBIL and inversely correlated with biliary excretion of pravastatin, a finding which could serve as a clue to uncover the regulatory system involving cooperation between GGT and Mrp2. In conclusion, BDC rats with HB, however mild, should be excluded from drug excretion studies to avoid the risk of underestimation of the biliary excretion of drugs.