Received for publication December 1, 2005.
Revised January 27, 2006.
Accepted for publication January 31, 2006.

In Vitro P-glycoprotein Inhibition Assays for Assessment of Clinical Drug Interaction Potential of New Drug Candidates: A Recommendation for Probe Substrates

Abstract

As modulation of P-glycoprotein (Pgp) through inhibition or induction can lead to drug-drug interactions by altering intestinal, CNS, renal or biliary efflux, it is anticipated that information regarding the potential interaction of drug candidates with Pgp will be a future regulatory expectation. Therefore, to be able to utilize in vitro Pgp inhibition findings to guide clinical drug interactions studies, the utility of five probe substrates (calcein-AM, colchicine, digoxin, prazosin and vinblastine) was evaluated by inhibiting their Pgp-mediated transport across MDR1-MDCKII monolayers with 20 diverse drugs having various degrees of Pgp interaction (e.g., efflux ratio, ATPase, and calcein-AM inhibition). Overall, the rank order of inhibition was generally similar with IC₅₀ values typically within 3- to 5-fold of each other. However, several notable differences in the IC₅₀ values were observed. Digoxin and prazosin were the most sensitive probes (e.g., lowest IC₅₀ values), followed by colchicine, vinblastine and calcein-AM. Inclusion of other considerations such as a large dynamic range, commercially available radiolabel, and a clinically meaningful probe makes digoxin an attractive probe substrate. Therefore, it is recommended that digoxin be considered as the standard in vitro probe to investigate the inhibition profiles of new drug candidates. Further, this study demonstrates that it may not be necessary to generate IC₅₀ values with multiple probe substrates for Pgp as is currently done for cytochrome P450 3A4. Finally, a strategy integrating results from in vitro assays (efflux, inhibition and ATPase) is provided to further guide clinical interaction studies.

Key words: ABC transporters, cytochrome P450, drug efflux, drug interactions, drug transport, hepatic transport, in vivo probes, membrane transport, p-glycoprotein, transporters

This article has been cited by other articles:

				N. Giri, S. Agarwal, N. Shaik, G. Pan, Y. Chen, and W. F. Elmquist Substrate-Dependent Breast Cancer Resistance Protein (Bcrp1/Abcg2)-Mediated Interactions: Consideration of Multiple Binding Sites in in Vitro Assay Design Drug Metab. Dispos., March 1, 2009; 37(3): 560 - 570. [Abstract] [Full Text] [PDF]

				L. Bousquet, A. Pruvost, A.-C. Guyot, R. Farinotti, and A. Mabondzo Combination of Tenofovir and Emtricitabine plus Efavirenz: In Vitro Modulation of ABC Transporter and Intracellular Drug Accumulation Antimicrob. Agents Chemother., March 1, 2009; 53(3): 896 - 902. [Abstract] [Full Text] [PDF]

				M. V. S. Varma, A. H. Eriksson, G. Sawada, Y. A. Pak, E. J. Perkins, and C. L. Zimmerman Transepithelial Transport of the Group II Metabotropic Glutamate 2/3 Receptor Agonist (1S,2S,5R,6S)-2-Aminobicyclo[3.1.0]hexane-2,6-dicarboxylate (LY354740) and Its Prodrug (1S,2S,5R,6S)-2-[(2'S)-(2'-Amino)propionyl]aminobicyclo[3.1.0]hexane-2,6-dicarboxylate (LY544344) Drug Metab. Dispos., January 1, 2009; 37(1): 211 - 220. [Abstract] [Full Text] [PDF]

				S. Vaidyanathan, G. Camenisch, H. Schuetz, C. Reynolds, C.-M. Yeh, M.-N. Bizot, H. A. Dieterich, D. Howard, and W. P. Dole Pharmacokinetics of the Oral Direct Renin Inhibitor Aliskiren in Combination With Digoxin, Atorvastatin, and Ketoconazole in Healthy Subjects: The Role of P-Glycoprotein in the Disposition of Aliskiren J. Clin. Pharmacol., November 1, 2008; 48(11): 1323 - 1338. [Abstract] [Full Text] [PDF]

				C. E. Garner, E. Solon, C.-M. Lai, J. Lin, G. Luo, K. Jones, J. Duan, C. P. Decicco, T. Maduskuie, S. E. Mercer, et al. Role of P-Glycoprotein and the Intestine in the Excretion of DPC 333 [(2R)-2-{(3R)-3-Amino-3-[4-(2-methylquinolin-4-ylmethoxy)phenyl]-2-oxopyrrolidin-1-yl}-N-hydroxy-4-methylpentanamide] in Rodents Drug Metab. Dispos., June 1, 2008; 36(6): 1102 - 1110. [Abstract] [Full Text] [PDF]

				D. Siccardi, K. L. Mumy, D. M. Wall, J. D. Bien, and B. A. McCormick Salmonella enterica serovar Typhimurium modulates P-glycoprotein in the intestinal epithelium Am J Physiol Gastrointest Liver Physiol, June 1, 2008; 294(6): G1392 - G1400. [Abstract] [Full Text] [PDF]

				J. M. Gow, L. M. Hodges, L. W. Chinn, and D. L. Kroetz Substrate-Dependent Effects of Human ABCB1 Coding Polymorphisms J. Pharmacol. Exp. Ther., May 1, 2008; 325(2): 435 - 442. [Abstract] [Full Text] [PDF]

				J. W. Polli, J. E. Humphreys, K. A. Harmon, S. Castellino, M. J. O'Mara, K. L. Olson, L. St. John-Williams, K. M. Koch, and C. J. Serabjit-Singh The Role of Efflux and Uptake Transporters in N-{3-Chloro-4-[(3-fluorobenzyl)oxy]phenyl}-6-[5-({[2-(methylsulfonyl)ethyl]amino}methyl)-2-furyl]-4-quinazolinamine (GW572016, Lapatinib) Disposition and Drug Interactions Drug Metab. Dispos., April 1, 2008; 36(4): 695 - 701. [Abstract] [Full Text] [PDF]

				P. Hsiao, T. Bui, R. J. Y. Ho, and J. D. Unadkat In Vitro-to-in Vivo Prediction of P-glycoprotein-Based Drug Interactions at the Human and Rodent Blood-Brain Barrier Drug Metab. Dispos., March 1, 2008; 36(3): 481 - 484. [Abstract] [Full Text] [PDF]

				P. Acharya, M. P. O'Connor, J. W. Polli, A. Ayrton, H. Ellens, and J. Bentz Kinetic Identification of Membrane Transporters That Assist P-glycoprotein-Mediated Transport of Digoxin and Loperamide through a Confluent Monolayer of MDCKII-hMDR1 Cells Drug Metab. Dispos., February 1, 2008; 36(2): 452 - 460. [Abstract] [Full Text] [PDF]

				C. B. Eap, M. Bochud, R. C. Elston, P. Bovet, M. P. Maillard, J. Nussberger, L. Schild, C. Shamlaye, and M. Burnier CYP3A5 and ABCB1 Genes Influence Blood Pressure and Response to Treatment, and Their Effect Is Modified by Salt Hypertension, May 1, 2007; 49(5): 1007 - 1014. [Abstract] [Full Text] [PDF]

				J. Weiss, J. Rose, C. H. Storch, N. Ketabi-Kiyanvash, A. Sauer, W. E. Haefeli, and T. Efferth Modulation of human BCRP (ABCG2) activity by anti-HIV drugs J. Antimicrob. Chemother., February 1, 2007; 59(2): 238 - 245. [Abstract] [Full Text] [PDF]