The Parallel Artificial Membrane Permeability Assay (PAMPA) is the non-cell based assay for predicting GI and Brain permeability of drugs in early drug discovery. It uses a lipid filled membrane to simulate the lipid bilayer of various cell types, including intestinal epithelium. Passive permeability assays are useful for screening oral-absorption potential of drug candidates. The PAMPA’s results correlate with human drug absorption value and its ability to mimic the target barrier can by enhanced by the optimization of the assay’s conditions.
Method: The PAMPA assay is carried out in a 96-well membrane filter based plate. The method involves measuring the diffusion of compounds from a Donor compartment, through a PVDF membrane filter that has been pre-treated with a lipid-containing organic solvent, into an Acceptor compartment.
After the artificial membrane has been applied to the PVDF membrane, plates are incubated, after which the Donor compartment is physically separated from the Acceptor compartment. The amount of compound in the Acceptor compartment is measured by LC/MS, HPLC or UV/Vis spectrophotometry, depending upon the physical properties of the compound.