Using Human Plasma as an Assay Medium in Caco-2 Studies Improves Mass Balance for Lipophilic Compounds

Area of Science:

• Pharmacokinetics and Drug Metabolism
• Cell Biology and Physiology

Background:

• Caco-2 permeability assays are crucial for predicting drug absorption.
• Lipophilic compounds often present challenges in Caco-2 studies due to poor mass balance and inadequate sink conditions.
• Optimizing assay conditions is essential for accurate drug permeability assessment.

Purpose of the Study:

• To evaluate human plasma as an alternative assay medium for Caco-2 permeability studies.
• To address limitations of poor mass balance and sink conditions with lipophilic compounds.
• To enhance the reliability of permeability measurements (Papp).

Main Methods:

• Caco-2 cell permeability was assessed using pH 7.4 buffer and human plasma.
• Reference compounds and antimalarial drugs were used to evaluate assay media.
• Permeability values (Papp) were corrected for the unbound fraction when using plasma.

Main Results:

• Human plasma did not compromise Caco-2 monolayer integrity or P-gp transporter function.
• Plasma improved mass balance and sink conditions, especially for lipophilic compounds.
• More reliable Papp values were obtained using plasma compared to buffer for challenging compounds.

Conclusions:

• Human plasma is a viable alternative assay medium for Caco-2 permeability studies.
• Using plasma enhances mass balance and improves permeability measurements for lipophilic drugs.
• This approach offers a more robust method for assessing drug absorption potential.