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An Integrated Approach to Identify Drug Transporters Involved in a Compounds Disposition During Prec

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The Challenge of Drug Transporters in ADME. Studies and Tools ... Angela Mote. Kevin D. Read. Larry Shampine. Giovanni Vitulli. Lindsey Webster. Joe Woolley ... – PowerPoint PPT presentation

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Title: An Integrated Approach to Identify Drug Transporters Involved in a Compounds Disposition During Prec


1
An Integrated Approach to Identify Drug
Transporters Involved in a Compounds Disposition
During Preclinical Development Joseph W. Polli,
Ph.D. Drug Metabolism and Pharmacokinetics Room
MAI.A2213.2G P.O. Box 13398 Research Triangle
Park, NC 27709 joseph.w.polli_at_gsk.com
2
Outline
  • The Challenge of Drug Transporters in ADME
  • Studies and Tools for Elucidating Drug
    Transporters
  • Examples of Influence of Drug Transporters on
    Drug Disposition
  • Conclusions

3
Influence of Drug Transporters on ADME
Tool Whole Body Autoradiography
Vd 3 L/kg liverblood 81 brainblood
1.51
Vd 6 L/kg liverblood 101 brainblood
0.11 PgP substrate
Vd 0.6 L/kg liverblood 191 brainblood
lt0.051 OATP substrate
4
The Challenge
Intestinal uptake OATP2B1, OATP1A2 PEPT-1, MRP3
Biliary secretion Pgp, MDR3, MRP2 (BSEP)
Hepatic uptake OATP1B1 OATP2B1
OAT2 OATP1B3 NTCP
Intestinal efflux Pgp, MRP2, BCRP
Hepatic efflux MRP3, MRP6
CNS efflux Pgp, OAT3, MRP1, MRP2, BCRP
Renal uptake OAT1,OAT3,OATP4C1 Renal
re-uptake OATP2B1, PEPT-2
Renal secretion Pgp, MRP2, OAT4
in red ATP dependent efflux transporters in
yellow exchange/co-transport transporters
5
Tools available to Elucidate Drug Transporters
  • Structure/Physicochemical Properties
  • In Vitro Transporter Assays
  • In Situ Tissue Perfusions
  • In Vivo/Pharmacokinetic Studies
  • Clinical Studies

6
Tools available to Elucidate Drug Transporters
  • Structure/Physicochemical Properties
  • Chemical Class
  • HIV PI- Pgp, Statins- OATP, PPARs- MRPs
  • Molecular Weight
  • gt400, Type I or II OCT, OAT vs. OATP
  • Organic Cation or Anion
  • Pgp, BCRP vs. OATP, MRP
  • Partition Coefficient (logP, logD)
  • ABC or SLC carrier
  • Pharmaceutical Properties
  • solubility, permeability (BCS), prodrug (peptide,
    BA)

7
Tools available to Elucidate Drug Transporters
  • In Vitro Transporter Assays
  • Uptake and Efflux Studies
  • cells, membranes vesicles and isolated tissues
  • Monolayer Transport Studies
  • Inhibition Studies
  • uptake, efflux, transport
  • Surrogate Transporter Activity
  • ATPase Studies (Pi)
  • Co-factor utilization

8
Tools available to Elucidate Drug Transporters
  • Preclinical Studies
  • Single and Repeat Dose Pharmacokinetics
  • Examine for linearity
  • Changes in genetic or chemical knockout animals
  • Toxicology Studies
  • Specific tissue toxicity or accumulation
  • Whole-body Autoradiography Studies
  • Distribution, accumulation or restriction
  • Mass Balance Excretion Studies
  • Absorption and elimination
  • In Situ Tissue Perfusions
  • Isolated perfused liver, gastrointestinal, brain
    perfusions

9
Tools available to Elucidate Drug Transporters
  • Clinical Studies
  • Single and Repeat Dose Pharmacokinetics
  • Drug Interaction Studies
  • Mass Balance Excretion Studies
  • Imaging Studies
  • In Situ Tissue Perfusions

10
Case Study I AAPS Compound
  • Physicochemical Properties
  • MW 600
  • Organic Acid
  • cLogP 4.1
  • Drugs in this therapeutic area are typically
    CYP3A4 and Pgp substrates
  • Solubility 20 ug/mL in FASSIF

11
Case Study I AAPS Compound
  • Absorption / Distribution
  • Tmax (h)- 1.5 h
  • F()- 10-20
  • Vd (L/kg) 0.4 (less than total body water)
  • Protein binding 95 bound, low BC partitioning
  • WBA ratios Brain- 0.01, liver- gt50, kidney- 3
  • Papp 40 nm/s (good), Pgp substrate (ratio 30)

12
Case Study I AAPS Compound
Metabolism/Elimination (PK and in vitro studies)
  • CLp (mL/min/kg) 25 (moderate)
  • t½ (h)- 2
  • P450 inhibition none
  • In vitro Hepatocyte-
  • Saturable uptake
  • 70 remaining after 4 h
  • IPRL bile 95, pefusate 2, liver 3
  • OATP1B1 inhibitor
  • IC50 0.7 uM

13
Case Study I AAPS Compound
Metabolism/Elimination (in vivo studies)
  • Mass Balance
  • Intact gt90 dose feces, lt2 urine
  • BDC 60-80 bile, 20-40 feces, lt2 urine
  • 60 of dose absorbed
  • Compare to F
  • Metabolite ID
  • mainly glucuronide metabolite found in bile,
    little parent present.

Reduction in biliary elimination suggests that
MRP2 involved
14
Case Study I AAPS Compound
  • Clinical
  • Greater than proportional change in PK
  • Conclusions
  • Preclinical and clinical studies support
    completing drug interaction studies for statins
    (OATP) and digoxin (Pgp, OATP).
  • Genotype PK outliers?

15
Case Study II GV196771
  • Compound that was being developed for neuropathic
    pain (Wallace, et al., Neurology 591694, 2002)
  • Potent antagonist of the modulatory glycine site
    of the NMDA receptor (Iavarone et al., J Clin
    Pharmacol 199929560)
  • Preliminary PK studies show low oral
    bioavailability in rat (10) and moderate oral
    bioavailability in dog (47)
  • Clearance in both species
  • was low (2 mL/min/kg)
  • Good in vitro permeability
  • (70-120 nm/s)

16
GV196771
  • Rat excretion balance studies
  • 94 of oral dose in feces, 75-85 parent
  • 5 of oral dose in bile, majority glucuronide
    metabolite, lt1 of dose in urine
  • WBA 40 to 100-fold higher levels of radiolabel
    in intestine than other tissues
  • Differences in bioavailablity most likely due to
    absorption and not first pass metabolism

Project Issue GV196771 had poor oral
bioavailability. Initial hypothesis Pgp
mediated efflux at the intestinal wall
17
The pharmacokinetics of GV196771 after Oral
administration at 1 mg/kg (free acid) to male
rats orally pretreated with 50 mg/kg GF120918 or
vehicle
Year 1996
GF120918 increased the oral AUC and Cmax of
GV196771 by 7.0- and 7.8-fold. Conclusion Pgp
limits the intestinal absorption of GV196771
18

Transport of GV196771 across MDR1-MDCK Monolayers
A apical, B basolateral. GV196771 was run
at a test concentration of 3 ?M and at a single
time point of 90 min. The Pgp efflux ratio is
calculated by Papp B?A / Papp A?B. n 3
monolayers. GF120918A was used at 2 ?M in
both donor and receiver compartments.
GV196771 is not a Pgp substrate (human and
mouse), an inhibitor of digoxin transport, or
activator of ATPase. Conclusion The mechanism
whereby GF120918 enhances the systemic exposure
of GV196771 likely does not involve Pgp.
19
Breast Cancer Resistance Protein (BCRP, MXR,
ABCG2)
  • 70kDa half transporter of the ABC family
  • Substrate specificities distinct but overlapping
    with P-gp and MRP1
  • Involved in multidrug resistance specifically
    known to cause resistance to anticancer drugs
    topotecan, mitoxantrone, doxorubicin and
    daunorubicin
  • Shown to be inhibited by GF120918 and ZD1839
    Iressa (ErbB2 inhibitor for cancer).

20
Transport of GV196771 across bcrp-MDCK Monolayers
GV196771 is a substrate of BCRP in vitro.
Conclusion This suggests that the BCRP protein
contributes to the observed poor bioavailability
of GV196771 in rats.
21
Mechanistic In Vivo Study Design
Support a role for both BCRP and Pgp in limiting
the absorption of GV196771.
22
Interplay of Drug Metabolizing Enzymes and
Transporters
Complex balance between a number of metabolic and
transport systems
23
BDDCS Interplay of Drug Transport and Metabolism
The interplay between physical properties,
transporters, and metabolic enzymes will
determine the impact on absorption. Benet et al,
Pharmaceutical Research, 2211-23, January 2005
24
Conclusions
  • The identification of transporters that influence
    the disposition and safety of drugs is a new
    challenge for drug discovery and development
    programs.
  • A variety of in vitro and in vivo assays are
    needed to elucidate the role of drug transporters
    in the disposition of a compound.
  • Our understanding of drug transporters is still
    emerging and it is likely that multiple ABC and
    SLC transporters will influence the disposition
    of a compound.

25
Acknowledgements
  • Transport Studies
  • Kim Adkison
  • Robert J. Barnaby
  • Todd M. Baughman
  • Luigina Bertolotti
  • Victoria Demby
  • Kelly Doan
  • Liyue Huang
  • Joan Humphreys
  • Jeanne Jarrett
  • Kelly Jordan
  • Angela Mote
  • Kevin D. Read
  • Larry Shampine
  • Giovanni Vitulli
  • Lindsey Webster
  • Joe Woolley
  • Steve Wring
  • GSK DMPK Colleagues
  • Andrew Ayrton
  • Harma Ellens
  • Jeevan Kunta
  • Paolo Rossato
  • Academic Colleagues
  • Ken Audus
  • Ron Borchardt
  • James Polli

  • Project Sponsors
  • Steven Clarke
  • Jane Harrelson
  • Cosette Serabjit-Singh

26

Summary of the the pharmacokinetics of GV196771.
These studies support a role for both BCRP and
Pgp in limiting the intestinal absorption of
GV196771.
27
Influence of Drug Transporters on ADME
Tool Whole Body Autoradiography
Vd 3 L/kg liverblood 81 brainblood
1.51
Vd 6 L/kg liverblood 101 brainblood
0.11 PgP substrate
Vd 0.6 L/kg liverblood 191 brainblood
lt0.051 OATP substrate
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