title: Estimation of inhibitory quotient using a comparative equilibrium dialysis assay for prediction of viral response to hepatitis C virus inhibitors.
abstract: The relationship of inhibitory quotient (IQ) with the virologic response to specific inhibitors of human hepatitis C virus (HCV) and the best method to correct for serum protein binding in calculating IQ have not been addressed. A common method is to determine a fold shift by comparing the EC(50) values determined in cell culture in the absence and presence of human serum (fold shift in EC(50) ), but this method has a number of disadvantages. In the present study, the fold shifts in drug concentrations between 100% human plasma (HP) and cell culture medium (CCM) were directly measured using a modified comparative equilibrium dialysis (CED) assay for three HCV protease inhibitors (PIs) and for a novel HCV inhibitor GS-9132. The fold shift values in drug concentration between the HP and CCM (CED ratio) were ∼1 for SCH-503034, VX-950 and GS-9132 and 13 for BILN-2061. These values were ∼3-10-fold lower than the fold shift values calculated from the EC(50) assay for all inhibitors except BILN-2061. Using the CED values, a consistent pharmacokinetic and pharmacodynamic relationship was observed for the four HCV inhibitors analysed. Specifically, an approximate 1 log(10) reduction in HCV RNA was achieved with an IQ close to 1, while 2-3 and greater log(10) reductions in HCV RNA were achieved with IQ values of 3-5 and greater, respectively. Thus, use of CED to define IQ provides a predictive and quantitative approach for the assessment of the in vivo potency of HCV PIs and GS-9132. This method provides a framework for the evaluation of other classes of drugs that are bound by serum proteins but require the presence of serum for in vitro evaluation.
authors.affiliation: Department of Clinical Virology, Gilead Sciences Inc., Foster City, CA, USA. Hongmei.Mo@gilead.com
authors.forename: H
authors.initials: H
authors.lastname: Mo
authors.forename: C
authors.initials: C
authors.lastname: Yang
authors.forename: K
authors.initials: K
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Huang
authors.forename: B
authors.initials: B
authors.lastname: Murray
authors.forename: X
authors.initials: X
authors.lastname: Qi
authors.forename: S-C
authors.initials: SC
authors.lastname: Sun
authors.forename: M
authors.initials: M
authors.lastname: Deshpande
authors.forename: G
authors.initials: G
authors.lastname: Rhodes
authors.forename: M D
authors.initials: MD
authors.lastname: Miller
mesh_terms: D000998:Antiviral Agents / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D001798:Blood Proteins / Q000378:metabolism; D002219:Carbamates / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D002460:Cell Line; D057186:Comparative Effectiveness Research; D003956:Dialysis / Q000379:methods; D016174:Hepacivirus / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D006526:Hepatitis C / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D020128:Inhibitory Concentration 50; D047028:Macrocyclic Compounds / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D008567:Membranes, Artificial; D009842:Oligopeptides / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D010670:Phenylthiourea / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D010949:Plasma / Q000821:virology; D011392:Proline / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D011480:Protease Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D011485:Protein Binding / Q000187:drug effects; D011804:Quinolines / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D012367:RNA, Viral / Q000097:blood; D013844:Thiazoles / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D019562:Viral Load / Q000187:drug effects*
chemical_list: C530651:1-(4-pentyloxy-3-trifluoromethylphenyl)-3-(pyridine-3-carbonyl)thiourea; D000998:Antiviral Agents; C479555:BILN 2061; D001798:Blood Proteins; D002219:Carbamates; D047028:Macrocyclic Compounds; D008567:Membranes, Artificial; D009842:Oligopeptides; D011480:Protease Inhibitors; D011804:Quinolines; D012367:RNA, Viral; D013844:Thiazoles; C486464:telaprevir; D010670:Phenylthiourea; C512204:N-(3-amino-1-(cyclobutylmethyl)-2,3-dioxopropyl)-3-(2-((((1,1-dimethylethyl)amino)carbonyl)amino)-3,3-dimethyl-1-oxobutyl)-6,6-dimethyl-3-azabicyclo(3.1.0)hexan-2-carboxamide; D011392:Proline