Protein and Tissue Binding

  • Allows prediction of in vivo drug concentration in blood
  • Identifies appropriate fluid medium for pharmacokinetic studies
  • Help determine the extent of distribution of a drug in vivo

Plasma Protein Binding

Plasma protein binding is critical in the early phases of drug development to determine the amount of a drug available for distribution throughout various organs and tissues in the body. In addition, these in vitro tests can predict the extent to which the drug will be bound to plasma proteins in vivo.

  • Low Protein Binding → High Free Drug Distribution
  • High Protein Binding → Low Free Drug Distribution
  • Protein bound drugs may have greater difficulty crossing cell membranes
  • Red Blood Cell / Plasma Partitioning
  • Multiple Species
  • Multiple Platform
    • Ultrafiltration
    • Equilibrium Dialysis