Effect of variations in the amounts of P-glycoprotein (ABCB1), BCRP (ABCG2) and CYP3A4 along the human small intestine on PBPK models for predicting intestinal first pass.
It is difficult to predict the first-pass effect in the human intestine due to a lack of scaling factors for correlating in vitro and in vivo data. We have quantified cytochrome P450/3A4 (CYP3A4) and two ABC transporters, P-glycoprotein (P-gp, ABCB1) and the breast cancer resistant protein BCRP (ABCG2), throughout the human small intestine to determine the scaling factors for predicting clearance from intestinal microsomes and develop a physiologically based pharmacokinetic (PBPK) model. CYP3A4, P-gp and BCRP proteins were quantified by Western blotting and/or enzyme activities in small intestine samples from 19 donors, and mathematical trends of these expressions with intestinal localization were established. Microsome fractions were prepared and used to calculate the amount of microsomal protein per gram of intestine (MPPGI). Our results showed a trend in CYP3A4 expression decrease from the upper to the lower small intestine while P-gp expression is increasing. In contrast, BCRP expression did not vary significantly with position, but varied greatly between individuals. The MPPGI (mg microsomal protein per centimeter intestine) remained constant along the length of the small intestine, at about 1.55 mg/cm. Moreover, intrinsic clearance measured with specific CYP3A4 substrates (midazolam and an in-house Servier drug) and intestinal microsomes was well correlated with the amount of CYP3A4 (R(2) > 0.91, p < 0.01). In vivo data were more accurately predicted using PBPK models of blood concentrations of these two substrates based on the segmental distributions of these enzymes and MPPGI determined in this study. Thus, these mathematical trends can be used to predict drug absorption at different intestinal sites and their metabolism can be predicted with the MPPGI.
Bruyère
Arnaud
A
INSERM U705-CNRS UMR 7157, Faculté de Pharmacie, Université Paris Descartes, Paris, France.
Declèves
Xavier
X
Bouzom
Francois
F
Ball
Kathryn
K
Marques
Catie
C
Treton
Xavier
X
Pocard
Marc
M
Valleur
Patrice
P
Bouhnik
Yoram
Y
Panis
Yves
Y
Scherrmann
Jean-Michel
JM
Mouly
Stephane
S
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001682:Biological Availability; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism*; D006801:Humans; D007408:Intestinal Absorption; D007421:Intestine, Small / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D008875:Middle Aged; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000378:metabolism*; D010599:Pharmacokinetics; D014018:Tissue Distribution
C513055:ABCB1 protein, human; C116614:ABCG2 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D009363:Neoplasm Proteins; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human