Enhancement of in vitro and in vivo microdialysis recovery of SB‐265123 using Intralipid ® and Encapsin ® as perfusates

This study was conducted to compare the ability of two potential microdialysis perfusates to enhance the recovery of SB‐265123, a lipophilic, highly protein‐bound compound, both in vitro and in vivo . Initial in vitro experiments established that the recovery of SB‐265123 by microdialysis using normal saline as a perfusate was poor (1.7%). Different concentrations of Intralipid ® and Encapsin ® also were evaluated in an identical in vitro setting, to determine enhancement of recovery. In vitro recovery was enhanced to approximately 24 and 65% with 5 and 20% Intralipid ® , and to approximately 59 and 62% with 5 and 20% Encapsin ® , respectively. A rat in vivo study was conducted with 20% Encapsin ® to confirm the in vitro observations. In the in vivo study, 75–80% recovery of free SB‐265123 was achieved using 20% Encapsin ® as a perfusate. The results from this study indicate that for SB‐265123, a lipophilic, highly protein‐bound molecule, Encapsin ® is an efficient recovery enhancer in vitro . The results from this investigation further demonstrate that a recovery enhancer may be useful for in vivo applications, even with a compound that is highly bound to plasma protein. Copyright © 2002 John Wiley & Sons, Ltd.