Transporters: Focus on OATP1B1 and Selected Renal Transporters Kathy Giacomini University of California, San Francisco

OCTs OCTNs OATs PEPT1 PEPT2 Organic Ions CNT1 CNT2 CNT3 Nucleosides ENT1 ENT2 Nucleosides DAT NET GAT1 SERT Neurotransmitters OATPs Organic Anions NRAMP1 DMT1 IREG1 Oligopeptides Fe +++ MATE1-2 MDR1 MDR3 BSEP MRP1-4 Hydrophobic Cations Hydrophobic Anions Organic Cations VMAT VAChT Selected Membrane Transporters in Human Genome ABC Family ~ 50 SLC Family ~ 300

Transporters in the Liver OAT2 OATP 1B1, 1B3 2B1 NTCP OCT1 MRP1,3 BCRP BSEP MRP2 MDR1,3 Hepatocyte Bile Blood

Is OATP1B1 Important for Drug-Drug Interactions? What is the evidence? In vitro evidence In vivo evidence

OATP1B1: benzylpenicillin, atorvastatin,cerivastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin, methotrexate, nateglinide, repaglinide, rifampin OATP1B3: digoxin, fexofenadine, fluvastatin, pravastatin,methotrexate, paclitaxel, rifampin OATP2B1: benzylpenicillin, fexofenadine, fluvastatin, pravastatin Selected Substrates of OATPs OATP 1B3 OATP 2B1 OATP 1B1

Is OATP1B1 Important for Drug-Drug Interactions? What is the evidence? In vitro evidence In vivo evidence

In Vivo Evidence Genetic Studies Knockout/transgenic Mice Polymorphisms in Humans Chemical Inhibition Studies

In Vivo Evidence Genetic Studies Knockout Mice: Not applicable Polymorphisms in Humans Chemical Inhibition Studies: Specific inhibitors not available

Individuals with Polymorphisms of OATP1B1 Have Higher Plasma Levels of Repaglinide Niemi M. et al, Clin Pharmacol Ther 2005; 77: Homozygous 521CC Homozygous 521TT

Individuals with Polymorphisms of ABCB1 Have Similar Plasma Levels of Repaglinide Niemi M. et al, Clin Pharmacol Ther 2005; 77:468-78

Individuals with Polymorphisms of CYP3A5 Have Similar Plasma Levels of Repaglinide

Niemi M. et al, British Journal of Clinical Pharmacology 2005, 59: Individuals with Polymorphisms of OATP1B1 Have Higher Plasma Levels of Fexofenadine Homozygous 521CC Homozygous 521TT

Niemi M. et al, Pharmacogenetics Jul;14(7): Individuals with Polymorphisms of OATP1B1 Have Higher Plasma Levels of Pravastatin 11187GA 11187GG

Niemi M. et al, Pharmacogenetics Jul;14(7): Individuals with Polymorphisms of OATP1B1 Have Higher Plasma Levels of Pravastatin 521CC 521TC 521TT

Niemi M. et al, Pharmacogenetics Jul;14(7): Individuals with Polymorphisms of OATP1B1 Have Higher Plasma Levels of Pravastatin *17 Heterozygotes

OATP1B1 Genetic Studies: Compelling Evidence that OATP1B1 Plays a Role in Drug Disposition Chemical Inhibition Studies: Specific inhibitors not available

Drug-Drug Interactions with Repaglinide +itraconazole +gemfibrozil +itraconazole+gemfibrozil Itraconazole: CYP3A4 inhibitor P-gp inhibitor Gemfibrozil: CYP2C8 and OATP1B1 inhibitor Niemi M. et al, Diabetologia Mar;46(3):

+trimethoprim Trimethoprim: CYP2C8 inhibitor Niemi M. et al, Br J Clin Pharmacol Apr;57(4):441-7 Increase in Plasma Levels of Repaglinide by Trimethoprim, A CYP2C8 Inhibitor

OATP1B1 Genetic Studies: Compelling evidence that OATP1B1 plays a role in drug disposition Chemical Inhibition Studies: Inhibitor studies are suggestive, but not definitive.

Recommendations to Consider Perform in vitro studies in cells expressing OATP1B1- Assess if NME is substrate/inhibitor If in vitro data show evidence of interaction with OATP1B1 – Substrate: Possibly perform clinical Interaction study with gemfibrozil or rifampicin as inhibitor of NME – Inhibitor: Possibly perform clinical Interaction study with NME as inhibitor of fexofenadine (no metabolism) or atorvastatin/pravastatin

OCTs OATs PEPT1 PEPT2 Organic Ions CNT1 CNT2 CNT3 Nucleosides ENT1 ENT2 Nucleosides DAT NET GAT1 SERT Neurotransmitters OATPs Organic Anions NRAMP1 DMT1 IREG1 Oligopeptides Fe +++ MATE1-2 MDR1 MDR3 BSEP MRP1-4 Hydrophobic Cations Hydrophobic Anions Organic Cations VMAT VAChT Selected Membrane Transporters in Human Genome ABC Family ~ 50 SLC Family ~ 300

Renal Drug Transporters Li M et al. Expert Opin Drug Metab Toxicol 2006 hOCT2/3 hOAT1/3 Urine Blood OCTN1/2MATE -1

Expression of Various Renal Transporters in Human Kidney Organic Cation Transporters (OCTs/OCTNs) Organic Anion Transporters (OATs) OCT2 OAT3 OAT1

OCT2, OAT1 and OAT3: Important for Drug- Drug Interactions? What is the evidence? In vitro evidence In vivo evidence

OAT1: acyclovir, adefovir, cidofovir, methotrexate OAT3: estrone sulfate, methotrexate, cimetidine, tetracycline OCT2: amantadine, memantine, cimetidine, metformin Selected Substrates of OATs and OCTs OAT3 OAT1 OCT2 OCTN1OCTN2

In Vivo Evidence Genetic Studies Knockout/transgenic Mice: Available Polymorphisms in Humans Chemical Inhibition Studies: Selective but not specific inhibitors are available

Knockout Mouse Models Oat1-/- Mice — Decreased CLR of para-aminohippurate, furosemide, endogenous organic anions (Eraly et al. J Biol Chem 2006) Oat3-/- Mice — Reduced uptake of para-aminohippurate, estrone sulfate in kidney slices and choroid plexus (Sweet et al. J Biol Chem 2002 ; Sykes et al. AJP Ren Physiol 2004) Oct1/2-/- Mice — Complete loss of active secretion of tetraethylammonium (Jonker et al. Mol Cell Biol 2003)

Preliminary Data on Cefotaxime and Genetic Variants of OAT3: Unpublished Data p = 0.045

Preliminary Data on Gabapentin and Genetic Variants of OCTN1: Unpublished Data CellsClinical

p = Preliminary Data on Gabapentin and Genetic Variants of OCTN1: Unpublished Data CellsClinical

In Vivo Evidence Genetic Studies Knockout/transgenic Mice: Available Polymorphisms in Humans Chemical Inhibition Studies: Selective but not specific inhibitors are available

Drug-Drug Interactions Related to Renal Drug Transporters Organic Anion Transporters (OATs): –Cefazolin/Probenecid (~38% ↓ cefazolin CL R ) (Spina et al. Ann Pharmacother 2003, Sakurai et al. Pharm Res 2004) Organic Cation Transporters (OCTs): –Procainamide/Cimetidine (42% ↓ procainamide CL R ) (Somogyi et al. Eur J Clin Pharmacol 1983) –Metformin/Cimetidine (28% ↓ metformin CL R ) (Somogyi et al. Br J Clin Pharmacol 1987)

Other DDIs Potentially Resulting From Renal Transporter Interactions Methotrexate/NSAIDs Furosemide/Probenecid Pindolol/Cimetidine Amiloride/Cimetidine Procainamide/Trimethoprim Charge Specific Inhibitors

Recommendations to Consider Perform in vitro studies in cells expressing OAT1, OAT3 or OCT2- Assess if NME is substrate/inhibitor If in vitro data show evidence of interaction with OCT2, OAT1 or OAT3 – Substrate of OCT2: Cimetidine inhibition – Inhibitor of OCT2: Metformin – Substrate of OATs: Probenecid – Inhibitor of OATs: Cefazolin