title: Microsomal and Cytosolic Scaling Factors in Dog and Human Kidney Cortex and Application for In Vitro-In Vivo Extrapolation of Renal Metabolic Clearance.
abstract: In vitro-in vivo extrapolation of drug metabolism data obtained in enriched preparations of subcellular fractions rely on robust estimates of physiologically relevant scaling factors for the prediction of clearance in vivo. The purpose of the current study was to measure the microsomal and cytosolic protein per gram of kidney (MPPGK and CPPGK) in dog and human kidney cortex using appropriate protein recovery marker and evaluate functional activity of human cortex microsomes. Cytochrome P450 (CYP) content and glucose-6-phosphatase (G6Pase) activity were used as microsomal protein markers, whereas glutathione-S-transferase activity was a cytosolic marker. Functional activity of human microsomal samples was assessed by measuring mycophenolic acid glucuronidation. MPPGK was 33.9 and 44.0 mg/g in dog kidney cortex, and 41.1 and 63.6 mg/g in dog liver (n= 17), using P450 content and G6Pase activity, respectively. No trends were noted between kidney, liver, and intestinal scalars from the same animals. Species differences were evident, as human MPPGK and CPPGK were 26.2 and 53.3 mg/g in kidney cortex (n= 38), respectively. MPPGK was 2-fold greater than the commonly used in vitro-in vivo extrapolation scalar; this difference was attributed mainly to tissue source (mixed kidney regions versus cortex). Robust human MPPGK and CPPGK scalars were measured for the first time. The work emphasized the importance of regional differences (cortex versus whole kidney-specific MPPGK, tissue weight, and blood flow) and a need to account for these to improve assessment of renal metabolic clearance and its extrapolation to in vivo.
authors.affiliation: Centre for Applied Pharmacokinetic Research, University of Manchester, Manchester (D.S., A.R.-H., A.G.); Newcastle University, Newcastle (S.B., C.D.A.B.); Biobank, Central Manchester University Hospitals NHS Foundation Trust, Manchester (J.B.); DMPK, Oncology iMed, AstraZeneca R&D, Alderley Park, Macclesfield (C.R.J.); and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Daniel
authors.initials: D
authors.lastname: Scotcher
authors.affiliation: Centre for Applied Pharmacokinetic Research, University of Manchester, Manchester (D.S., A.R.-H., A.G.); Newcastle University, Newcastle (S.B., C.D.A.B.); Biobank, Central Manchester University Hospitals NHS Foundation Trust, Manchester (J.B.); DMPK, Oncology iMed, AstraZeneca R&D, Alderley Park, Macclesfield (C.R.J.); and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Sarah
authors.initials: S
authors.lastname: Billington
authors.affiliation: Centre for Applied Pharmacokinetic Research, University of Manchester, Manchester (D.S., A.R.-H., A.G.); Newcastle University, Newcastle (S.B., C.D.A.B.); Biobank, Central Manchester University Hospitals NHS Foundation Trust, Manchester (J.B.); DMPK, Oncology iMed, AstraZeneca R&D, Alderley Park, Macclesfield (C.R.J.); and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Jay
authors.initials: J
authors.lastname: Brown
authors.affiliation: Centre for Applied Pharmacokinetic Research, University of Manchester, Manchester (D.S., A.R.-H., A.G.); Newcastle University, Newcastle (S.B., C.D.A.B.); Biobank, Central Manchester University Hospitals NHS Foundation Trust, Manchester (J.B.); DMPK, Oncology iMed, AstraZeneca R&D, Alderley Park, Macclesfield (C.R.J.); and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Jones
authors.affiliation: Centre for Applied Pharmacokinetic Research, University of Manchester, Manchester (D.S., A.R.-H., A.G.); Newcastle University, Newcastle (S.B., C.D.A.B.); Biobank, Central Manchester University Hospitals NHS Foundation Trust, Manchester (J.B.); DMPK, Oncology iMed, AstraZeneca R&D, Alderley Park, Macclesfield (C.R.J.); and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Colin D A
authors.initials: CDA
authors.lastname: Brown
authors.affiliation: Centre for Applied Pharmacokinetic Research, University of Manchester, Manchester (D.S., A.R.-H., A.G.); Newcastle University, Newcastle (S.B., C.D.A.B.); Biobank, Central Manchester University Hospitals NHS Foundation Trust, Manchester (J.B.); DMPK, Oncology iMed, AstraZeneca R&D, Alderley Park, Macclesfield (C.R.J.); and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom.
authors.forename: Amin
authors.initials: A
authors.lastname: Rostami-Hodjegan
authors.affiliation: Centre for Applied Pharmacokinetic Research, University of Manchester, Manchester (D.S., A.R.-H., A.G.); Newcastle University, Newcastle (S.B., C.D.A.B.); Biobank, Central Manchester University Hospitals NHS Foundation Trust, Manchester (J.B.); DMPK, Oncology iMed, AstraZeneca R&D, Alderley Park, Macclesfield (C.R.J.); and Simcyp Limited (a Certara Company), Blades Enterprise Centre, Sheffield (A.R.-H.), United Kingdom Aleksandra.Galetin@manchester.ac.uk.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Galetin
mesh_terms: D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism*; D004285:Dogs; D005260:Female; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D006801:Humans; D007672:Kidney Cortex / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008861:Microsomes / Q000737:chemistry / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D003577:Cytochrome P-450 Enzyme System; D005952:Glucose-6-Phosphatase