PT  - JOURNAL ARTICLE
AU  - Peter Ballard
AU  - Malcolm Rowland
TI  - Correction for Nonspecific Binding to Various Components of Ultrafiltration Apparatus and Impact on Estimating In Vivo Rat Clearance for a Congeneric Series of 5-Ethyl, 5-<em>n</em>-Alkyl Barbituric Acids
AID  - 10.1124/dmd.111.040683
DP  - 2011 Dec 01
TA  - Drug Metabolism and Disposition
PG  - 2165--2168
VI  - 39
IP  - 12
4099  - http://dmd.aspetjournals.org/content/39/12/2165.short
4100  - http://dmd.aspetjournals.org/content/39/12/2165.full
SO  - Drug Metab Dispos2011 Dec 01; 39
AB  - Accurately predicting in vivo metabolic clearance from in vitro liver microsomes or hepatocytes requires a good understanding of the factors contributing to the prediction. Although much work has concentrated on deriving scaling factors and optimizing the metabolic stability techniques for consistency and rigor, it is only relatively recently that the importance of binding to microsomes and hepatocytes has been appreciated. Ultrafiltration is often used to estimate binding to plasma proteins and microsomes, but the level of nonspecific binding (NSB) to the ultrafiltration apparatus has not been adequately described. We derive an equation to correct for NSB and demonstrate that this can significantly affect the estimate of binding to microsomes and improve the accuracy of scaling to in vivo clearance for a series of barbiturates.