Permeability is the rate at which a compound passes through a biological barrier.
This process is involved in intestinal absorption but also in the distribution of compounds from the blood to organs like liver, brain, kidneys.
The majority of drugs enter the bloodstream by passive diffusion through the intestinal epithelium.
PAMPA (Parallel Artificial Membrane Permeability Assay) is an in vitro model of passive absorption.

Protocol

MatrixPBS pH 7.4
MembraneSolution of 2% phosphatidylcholine in dodecane 
Test concentration10µM
Test temperatureRoom temperature
Incubation time16h
ControlsChloramphenicol, Testosterone
Analysis methodLC-MS/MS
Data deliveryLog Pe
Replicate3

Data

Notes

The PAMPA method can not predicts passive diffusion.

All the mechanisms involved in intestinal permeability are studied with another method: Caco-2.