Stereoselectivity of biliary excretion of 2-arylpropionates in rats

To examine the stereoselectivity of biliary excretion, the optically pure enantiomers of ketoprofen (KT), ibuprofen (IBU), and flurbiprofen (FLU) were intravenously administered to normal and bile duct‐cannulated rats at 10 mg/kg. The recovery of total KT in bile was significantly higher after administration of (S)‐KT than after (R)‐KT [90.1 ± 3.5% vs 68.8 ± 8.2%, n =3, P < 0.05]. In normal rats the terminal half‐life of (R)‐KT was significantly shorter than that of (S)‐KT after administration of (R)‐KT (2.2 ± 0.6 h vs 14.3 ± 4.9 h, n = 3, P < 0.05). The terminal half‐life of both enantiomers was significantly shorter in rats with continuous bile drainage as compared to normal rats. No significant differences in pharmacokinetic parameters could be found between both enantiomers in bile duct‐cannulated animals. The total amount of IBU in bile was slightly higher after administration of (S)‐IBU than after (R)‐IBU administration. The percentage of (R)‐IBU after (R)‐IBU administration, however, was very low [(R)‐IBU: 1.5 ± 0.9%, (S)‐IBU: 23.4 ± 5.8%]. In normal rats the clearance of (R)‐IBU was significantly higher as compared to (S)‐IBU. Differences in pharmacokinetic parameters between normal and bile duct‐cannulated rats were not statistically significant due to high interindividual variability. The total recovery of FLU, which was excreted in bile to a lower extent than either KT or IBU, also tended to be greater after S‐enantiomer administration. Only small amounts of (S)‐FLU could be recovered in bile after (R)‐FLU administration. The pharmacokinetic parameters did not differ significantly between (R)‐ and (S)‐FLU or between normal and bile duct‐cannulated rats due to its low inversion rate and low excretion via bile. © 1993 Wiley‐Liss, Inc.