title: Blood-brain barrier (BBB) pharmacoproteomics: reconstruction of in vivo brain distribution of 11 P-glycoprotein substrates based on the BBB transporter protein concentration, in vitro intrinsic transport activity, and unbound fraction in plasma and brain in mice.
abstract: The purpose of this study was to examine whether in vivo drug distribution to the brain can be reconstructed by integrating P-glycoprotein (P-gp)/mdr1a expression levels, P-gp in vitro activity, and drug unbound fractions in mouse plasma and brain. For 11 P-gp substrates, in vitro P-gp transport activities were determined by measuring transcellular transport across monolayers of mouse P-gp-transfected LLC-PK1 (L-mdr1a) and parental cells. P-gp expression amounts were determined by quantitative targeted absolute proteomics. Unbound drug fractions in plasma and brain were obtained from the literature and by measuring brain slice uptake, respectively. Brain-to-plasma concentration ratios (K(p brain)) and its ratios between wild-type and mdr1a/1b(-/-) mice (K(p brain) ratio) were obtained from the literature or determined by intravenous constant infusion. Unbound brain-to-plasma concentration ratios (K(p,uu,brain)) were estimated from K(p brain) and unbound fractions. Based on pharmacokinetic theory, K(p brain) ratios were reconstructed from in vitro P-gp transport activities and P-gp expression amounts in L-mdr1a cells and mouse brain capillaries. All reconstructed K(p brain) ratios were within a 1.6-fold range of observed values. K(p brain) then was reconstructed from the reconstructed K(p brain) ratios and unbound fractions. K(p,uu,brain) was reconstructed as the reciprocal of the reconstructed K(p brain) ratios. For quinidine, loperamide, risperidone, indinavir, dexamethasone, paclitaxel, verapamil, loratadine, and diazepam, the reconstructed K(p brain) and K(p,uu,brain) agreed with observed and estimated in vivo values within a 3-fold range, respectively. Thus, brain distributions of P-gp substrates can be reconstructed from P-gp expression levels, in vitro activity, and drug unbound fractions.
authors.affiliation: Division of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Uchida
authors.forename: Sumio
authors.initials: S
authors.lastname: Ohtsuki
authors.forename: Junichi
authors.initials: J
authors.lastname: Kamiie
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Terasaki
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism*; 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; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects*; D001812:Blood-Brain Barrier / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D004285:Dogs; D055808:Drug Discovery; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000493:pharmacokinetics; D007668:Kidney; D018374:LLC-PK1 Cells; D008297:Male; D051379:Mice; D008954:Models, Biological; D004364:Pharmaceutical Preparations / Q000097:blood* / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D011802:Quinidine / Q000378:metabolism / Q000493:pharmacokinetics; D013552:Swine
chemical_list: 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; C501412:Abcg2 protein, mouse; D004791:Enzyme Inhibitors; D004364:Pharmaceutical Preparations; C095122:multidrug resistance protein 3; D011802:Quinidine