Determination of gastrointestinal and skin permeability using the parallel artificial membrane permeability assay (PAMPA), provides a simplified approach to permeability by addressing mainly passive diffusion.

This avoids the complexities of active transport and metabolism, enabling ranking of the compounds on a single permeability factor that can be used to guide structural modifications of discovery compounds to improve their in vivo characteristics.

Values of permeability through a lipid layer simulating the GI barrier (GIT-PAMPA) or the skin barrier (Skin-PAMPA) are obtained in a high throughput format via HPLC analysis.