Estimation of inhibitory quotient using a comparative equilibrium dialysis assay for prediction of viral response to hepatitis C virus inhibitors

J Viral Hepat. 2011 May;18(5):338-48. doi: 10.1111/j.1365-2893.2010.01314.x.

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.

MeSH terms

  • Antiviral Agents / pharmacokinetics
  • Antiviral Agents / pharmacology*
  • Antiviral Agents / therapeutic use
  • Blood Proteins / metabolism
  • Carbamates / pharmacokinetics
  • Carbamates / pharmacology
  • Carbamates / therapeutic use
  • Cell Line
  • Comparative Effectiveness Research
  • Dialysis / methods
  • Hepacivirus / drug effects*
  • Hepacivirus / genetics
  • Hepacivirus / pathogenicity
  • Hepatitis C / drug therapy*
  • Hepatitis C / virology
  • Humans
  • Inhibitory Concentration 50
  • Macrocyclic Compounds / pharmacokinetics
  • Macrocyclic Compounds / pharmacology
  • Macrocyclic Compounds / therapeutic use
  • Membranes, Artificial
  • Oligopeptides / pharmacokinetics
  • Oligopeptides / pharmacology
  • Oligopeptides / therapeutic use
  • Phenylthiourea / analogs & derivatives
  • Phenylthiourea / pharmacokinetics
  • Phenylthiourea / pharmacology
  • Phenylthiourea / therapeutic use
  • Plasma / virology
  • Proline / analogs & derivatives
  • Proline / pharmacokinetics
  • Proline / pharmacology
  • Proline / therapeutic use
  • Protease Inhibitors / pharmacokinetics
  • Protease Inhibitors / pharmacology*
  • Protease Inhibitors / therapeutic use
  • Protein Binding / drug effects
  • Quinolines / pharmacokinetics
  • Quinolines / pharmacology
  • Quinolines / therapeutic use
  • RNA, Viral / blood
  • Thiazoles / pharmacokinetics
  • Thiazoles / pharmacology
  • Thiazoles / therapeutic use
  • Viral Load / drug effects*

Substances

  • 1-(4-pentyloxy-3-trifluoromethylphenyl)-3-(pyridine-3-carbonyl)thiourea
  • Antiviral Agents
  • BILN 2061
  • Blood Proteins
  • Carbamates
  • Macrocyclic Compounds
  • Membranes, Artificial
  • Oligopeptides
  • Protease Inhibitors
  • Quinolines
  • RNA, Viral
  • Thiazoles
  • telaprevir
  • Phenylthiourea
  • 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
  • Proline