Establishment of In Vitro P-Glycoprotein Inhibition Assay and Its Exclusion Criteria to Assess the Risk Of Drug–Drug Interaction at the Drug Discovery Stage

• Published in: Journal of pharmaceutical sciences Vol. 100; no. 9; pp. 4013 - 4023
• Main Authors: Sugimoto, Hiroshi, Matsumoto, Shin-Ichi, Tachibana, Miho, Niwa, Shin-Ichi, Hirabayashi, Hideki, Amano, Nobuyuki, Moriwaki, Toshiya
• Format: Journal Article
• Language: English
• Published: Hoboken Elsevier Inc 01.09.2011; Wiley Subscription Services, Inc., A Wiley Company; Wiley; American Pharmaceutical Association; Elsevier Limited
• Subjects: Animals; ATP-Binding Cassette, Sub-Family B, Member 1 - antagonists & inhibitors; Biological and medical sciences; difference of IC50 values; digoxin; Digoxin - pharmacokinetics; Drug Discovery; Drug Interactions; General pharmacology; Humans; in vitro models; In Vitro Techniques; Inhibitory Concentration 50; LLC-PK1 Cells; mathematical model; Medical sciences; P-glycoprotein; P-gp inhibition; Pharmaceutical technology. Pharmaceutical industry; pharmacokinetics; Pharmacology. Drug treatments; risk assessment for DDI; Swine; transporters; P-glycoprotein; drug interactions; transporters; risk assessment for DDI; in vitro models; P-gp inhibition; mathematical model; pharmacokinetics; difference of IC50 values; digoxin; Purine nucleoside; Antiretroviral agent; Cardiotonic agent; RNA-directed DNA polymerase; Digoxin; P Glycoprotein; values; difference of IC; Research and development; Assay; Reverse transcriptase inhibitor; Nucleoside analog; Antiviral; Glycoside; Drug interaction; Mathematical model; Digitalis drug; Carrier protein; Drug; Evaluation; Pharmaceutical technology; Enzyme; Transferases; Enzyme inhibitor; In vitro; Nucleotidyltransferases; Dideoxynucleoside; Risk factor; Didanosine; Pharmacokinetics
• ISSN: 0022-3549; 1520-6017
• DOI: 10.1002/jps.22652

The decision tree to determine whether the P-glycoprotein (P-gp)/multidrug resistance protein 1 (MDR1)-mediated drug–drug interaction (DDI) study is recommended has been proposed by the International Transporter Consortium. We, therefore, designed an in vitro P-gp inhibition assay and determined the appropriate risk criteria for P-gp-mediated DDI at the drug discovery stage. Effects of P-gp inhibitors on digoxin transport across a monolayer of MDR1-expressing cells were examined. The IC50 (half-maximal inhibitory concentration) values generated from the efflux ratio (ER) were smaller than those generated from basolateral-to-apical directional apparent permeability. The difference in IC50 values was kinetically described in a compartment model analysis. This analysis indicated that ER is a highly sensitive parameter that can be used for the degree of P-gp inhibition. Considering IC50 values and the increase in digoxin exposure in clinical DDI studies, the risk criteria of [I2]/IC50 = 30 ([I2], theoretically maximal gastrointestinal concentration) was the optimal cutoff value to predict a clinically relevant DDI. We also investigated whether the IC50 value itself is applicable to assess the DDI risk. In conclusion, compounds with IC50 values less than 2 μM exhibit high risk for P-gp-mediated DDIs. However, compounds with IC50 values greater than or equal to 2 μM are inconclusive because clinical doses should be considered for the precise DDI risk assessment. © 2011 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:4013–4023, 2011