PT  - JOURNAL ARTICLE
AU  - Jialin Mao
AU  - Michael Mohutsky
AU  - John Harrelson
AU  - Steven Wrighton
AU  - Stephen Hall
TI  - Predictions of CYP-Mediated Drug-Drug Interactions Using Cryopreserved Human Hepatocytes: Comparison of Plasma and Protein-Free Media Incubation Conditions
AID  - 10.1124/dmd.111.043158
DP  - 2012 Jan 01
TA  - Drug Metabolism and Disposition
PG  - dmd.111.043158
4099  - http://dmd.aspetjournals.org/content/early/2012/01/06/dmd.111.043158.short
4100  - http://dmd.aspetjournals.org/content/early/2012/01/06/dmd.111.043158.full
AB  - Cryopreserved human hepatocytes suspended in human plasma (HHSHP) have previously provided accurate CYP3A drug-drug interaction (DDI) predictions from a single IC50 that captures both reversible and time-dependent inhibition (TDI). The goal of this study was to compare the accuracy of DDI predictions by a protein-free human hepatocyte system combined with the fraction unbound in plasma for inhibitor(s) with those obtained with protein-containing incubations. Seventeen CYP3A, CYP2C9 or CYP2D6 inhibitors were incubated with hepatocytes in human plasma or hepatocyte maintenance medium (HMM) for 20 min over a range of concentrations after which midazolam 1'-hydroxylation, diclofenac 4'-hydroxylation or (R)- bufuralol 1'-hydroxylation were used to quantify the corresponding CYP catalytic activities. The IC50 values were obtained using a single incubation time, and converted to the corresponding apparent inhibition parameter Ki,app. For each inhibitor/drug pair examined, two methods were utilized to predict the ratio of human plasma area under the curve of the victim drug in the presence and absence of inhibitor. The HMM Ki, app values were combined with the free average systemic plasma concentration ("free [I] with HMM Ki,app" method) and the plasma Ki, app values were combined with the total average systemic plasma concentration ("total [I] with Plasma Ki,app" method). Of 63 clinical DDI studies identified in the literature, the "total [I] with Plasma Ki,app" method predicted 89% of cases within 2-fold of the reported interaction whereas the "free [I] with HMM Ki,app" method predicted only 59%. There was a general underprediction by the "free [I] with HMM Ki,app" method, which is consistent with an underestimation of in vitro inhibition potency in this system. In conclusion, the HHSHP system proved to be a simple, accurate predictor of DDIs for 3 major CYPs and superior to the protein-free approach.