Utility of Oatp1a/1b-knockout and OATP1B1/3-humanized mice in the study of OATP-mediated pharmacokinetics and tissue distribution: case studies with pravastatin, atorvastatin, simvastatin, and carboxydichlorofluorescein

Drug Metab Dispos. 2014 Jan;42(1):182-92. doi: 10.1124/dmd.113.054783. Epub 2013 Nov 5.

Abstract

Although organic anion transporting polypeptide (OATP)-mediated hepatic uptake is generally conserved between rodents and humans at a gross pharmacokinetic level, the presence of three major hepatic OATPs with broad overlap in substrate and inhibitor affinity, and absence of rodent-human orthologs preclude clinical translation of single-gene knockout/knockin findings. At present, changes in pharmacokinetics and tissue distribution of pravastatin, atorvastatin, simvastatin, and carboxydichlorofluorescein were studied in oatp1a/1b-knockout mice lacking the three major hepatic oatp isoforms, and in knockout mice with liver-specific knockin of human OATP1B1 or OATP1B3. Relative to wild-type controls, oatp1a/1b-knockout mice exhibited 1.6- to 19-fold increased intravenous and 2.1- to 115-fold increased oral drug exposure, due to 33%-75% decreased clearance, 14%-60% decreased volume of distribution, and ≤74-fold increased oral bioavailability, with the magnitude of change depending on the contribution of oatp1a/1b to pharmacokinetics. Hepatic drug distribution was 4.2- to 196-fold lower in oatp1a/1b-knockout mice; distributional attenuation was less notable in kidney, brain, cardiac, and skeletal muscle. Knockin of OATP1B1 or OATP1B3 partially restored control clearance, volume, and bioavailability values (24%-142% increase, ≤47% increase, and ≤77% decrease vs. knockout, respectively), such that knockin pharmacokinetic profiles were positioned between knockout and wild-type mice. Consistent with liver-specific humanization, only hepatic drug distribution was partially restored (1.3- to 6.5-fold increase vs. knockout). Exposure and liver distribution changes in OATP1B1-humanized versus knockout mice predicted the clinical impact of OATP1B1 on oral exposure and contribution to human hepatic uptake of statins within 1.7-fold, but only after correcting for human/humanized mouse liver relative protein expression factor (OATP1B1 = 2.2, OATP1B3 = 0.30).

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Animals
  • Atorvastatin
  • Biological Availability
  • Heptanoic Acids / pharmacokinetics*
  • Humans
  • Liver / metabolism
  • Liver-Specific Organic Anion Transporter 1
  • Mice
  • Mice, Knockout
  • Middle Aged
  • Organic Anion Transporters / metabolism*
  • Organic Anion Transporters, Sodium-Independent / metabolism*
  • Organic Cation Transport Proteins / metabolism*
  • Pravastatin / pharmacokinetics*
  • Pyrroles / pharmacokinetics*
  • Simvastatin / pharmacokinetics*
  • Solute Carrier Organic Anion Transporter Family Member 1B3
  • Tissue Distribution / physiology
  • Young Adult

Substances

  • Heptanoic Acids
  • Liver-Specific Organic Anion Transporter 1
  • Organic Anion Transporters
  • Organic Anion Transporters, Sodium-Independent
  • Organic Cation Transport Proteins
  • Pyrroles
  • SLCO1B1 protein, human
  • SLCO1B3 protein, human
  • Solute Carrier Organic Anion Transporter Family Member 1B3
  • Atorvastatin
  • Simvastatin
  • Pravastatin