APP NOTE: Accurate absorption measurement

BEDFORD, Mass.—As an in vitro measure of the absorption of compounds by human cells, PAMPA has found increasing use in recent years. While the assay works well for most compounds, however, it often inaccurately characterizes some high-permeability compounds as poor absorbers. At the recent SBS conference in Seattle, researchers at BD Biosciences described a new PAMPA membrane formulation that dramatically reduces the error rate.

 

Using standard 96-well PVDF filter plates, the researchers used a proprietary coating method (about which they offered no information) to layer a DOPC artificial membrane. They then compared the permeability of a variety of well and poorly absorbed compounds through the new and traditional PAMPA plates with literature data for in vivo human absorption.

 

The researchers found that the new DOPC coating method provided superior results for compounds that tended to give false-negative results in traditional PAMPA, with permeabilities much closer to literature values. Furthermore, they found the new PAMPA plates offered lower mass retention of "sticky" compounds.