Applications for TRANSIL assays

1. Brain Tissue Binding
2. Brain-to-Plasma Distribution
3. Liver Microsomal Binding
4. Plasma Protein Binding

1. Brain Tissue Binding

  • Efficacy of drugs depends on potency and drug concentration in tissue

  • Pharmacodynamics of CNS drugs only related to free drug in brain

  • Free drug in brain depends on total brain concentration and fraction unbound in brain

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2. Brain-to-Plasma Distribution

  • Blood Brain Barrier protects the brain from xenobiotics while maintaining metabolic functions

  • Significant hurdle for CNS targeted drugs

  • Important protection from drug side-effects

  • CNS-accessible chemical space much smaller incomparison to other organs (2 to 20%)

3. Liver Microsomal Binding

  • Liver microsomes are used to assess metabolic
    stability of drugs

  • Stability is assessed via disappearance of
    compound

  • Compound binding to microsomal membranes
    confounds stability estimates

  • Affinity to liver microsomal membranes can beused to correct for membrane binding

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4. Plasma Protein Binding

  • Only the unbound drug fraction penetrates tissues

  • High population differences in plasma binding

  • Plasma composition variable