Title: An Integrated Approach to Identify Drug Transporters Involved in a Compounds Disposition During Prec
1An 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
2Outline
- The Challenge of Drug Transporters in ADME
- Studies and Tools for Elucidating Drug
Transporters - Examples of Influence of Drug Transporters on
Drug Disposition - Conclusions
3Influence 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
4The 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
5Tools available to Elucidate Drug Transporters
- Structure/Physicochemical Properties
- In Vitro Transporter Assays
- In Situ Tissue Perfusions
- In Vivo/Pharmacokinetic Studies
- Clinical Studies
6Tools 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)
7Tools 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
8Tools 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
9Tools 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
10Case 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
11Case 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)
12Case 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
13Case 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
14Case 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?
15Case 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)
16GV196771
- 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
17The 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.
19Breast 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).
20Transport 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.
21Mechanistic In Vivo Study Design
Support a role for both BCRP and Pgp in limiting
the absorption of GV196771.
22Interplay of Drug Metabolizing Enzymes and
Transporters
Complex balance between a number of metabolic and
transport systems
23BDDCS 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
24Conclusions
- 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.
25Acknowledgements
- 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.
27Influence 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