Introduction
Parallel Artificial Membrane Permeability Assay (PAMPA) is a cell-free permeation model used to predict passive drug transport. Passive diffusion is an important factor in determining the absorption of orally administered compounds in the gastrointestinal tract (GIT), penetration of the blood-brain barrier (BBB), and general transport across cell membranes. PAMPA provides a simplified method by addressing only a single transport mechanism, avoiding the complexities of active transport and metabolism.
Depending on the lipid and buffers used, PAMPA can predict gastrointestinal tract absorption (PAMPA-GIT), blood-brain barrier permeability (PAMPA-BBB) or transdermal penetration (Skin-PAMPA). Generally, PAMPA is carried out in the early phase of drug discovery to select leads with promising oral bioavailability/brain penetration potential by ranking candidates in a cost-effective manner. By combining the data generated in PAMPA with more labor-intensive (as well as more predictive) cell-based permeability assays, quick structural modification of discovery compounds can be efficiently guided.
Assay Principle
The PAMPA assay for permeability measurement is based on the diffusion of a compound of interest through an artificial membrane. The PAMPA artificial membrane has a lipid-oil-lipid tri-layer structure constructed in the pores of a porous filter. The oil layer in the middle, which maintains a robust and stable PAMPA membrane, is ultra-thin to minimize compound retention and interference with the compound permeation.
Assay Protocol
| Test Compound Requirement | 1-2 mg dry powder or 100-200 µL of 10 mM DMSO stock solution |
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| Number of Replicates | 4 |
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| Incubation Time | 5 hours |
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| Temperature | Room temperature |
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| pH | 7.4 or other selected pH |
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| Test Article Requirements | 100 µL of 10 mM DMSO solution |
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| Integrity Marker | Lucifer Yellow |
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| Analysis Method | UV absorbance or LC-MS/MS if necessary |
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| Data Delivery | Apparent permeability coefficient (Papp), mass retention (R) |
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PAMPA Models Available at Creative Bioarray
- Original PAMPA – The lipid solution consists of 10% lecithin in dodecane.
- DOPC-PAMPA – The lipid solution consists of 2% DOPC in dodecane.
- HDM-PAMPA – The lipid solution is 100% hexadecane.
- Bio-mimetic PAMPA (BM-PAMPA) – The lipid solution consists of a mixture of PC, PE, PS, PI and cholesterol in an organic solvent.
- Double-Sink™ PAMPA (DS-PAMPA) – The lipid solution consists of 20% dodecane solution of a phospholipid mixture and the acceptor solution contains a surfactant mixture.
Using Creative Bioarray's ADME screening services is the fastest and most cost-effective way to get permeability predictions for your compounds. For more detailed information, please feel free to contact us or sent us an inquiry directly.
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