Parallel Artificial Membrane Permeability Assay (PAMPA)
Creative Animodel is a leading biotech company specialized in providing services of preclinical pharmacokinetics. Based on a highly automated approach, Creative Animodel delivers consistent and high quality data for our customers with a high cost performance.
What Is PAMPA?
Cell based assays for permeability screening, such as Caco-2 for oral absorption, tend to be moderate throughput, expensive, labor intensive, and composed of multiple transport mechanisms. Recent development of the PAMPA provides a simple, low-cost, high-throughput, and single mechanism method for permeability screening. PAMPA is used for high-throughput permeability assessment. This method utilizes an artificial phospholipid membrane created on a polymer filter between two aqueous chambers. It is demonstrated that parallel artificial membrane permeability is correlated with human intestinal absorption. The PAMPA measures only passive diffusion, which is different from cell permeability assays. This single mechanism process allows the diagnosis of the root cause for poor absorption,to drive synthetic modification for property improvement. There is a trend in the industry to use PAMPA as the first line permeability screen and use the cell based assays as secondary assays for mechanistic studies and diagnostic purposes.
Figure 1. HDM-PAMPA model with human serum albumin (Bujard, A. 2017)
PAMPA is performed in a 96 microtiter well plate containing two parts. All the wells at the bottom part are filled with buffer solution. The top part contains a series of filter-immobilized artificial membranes composed of lipids, which match with the wells in the bottom part. One-half of the filters on the top part are treated with an organic solvent, which supposedly acts as the cell membrane, and the other half are wetted with methanol/buffer. The test compound under investigation is applied to the top filters and the rate of appearance of the compound in the bottom wells should reflect the diffusion across the lipid layer. In recent studies, a good correlation was found between diffusion in the PAMPA system and percentage absorption in humans for a selected series of compounds.
Our PAMPA Models
The filter immobilized artificial membranes are prepared by dispersing a phospholipid with the help of an organic solvent. The problem of precipitation with low solubility compounds—when working at clinically relevant doses in cellular assays—is prevented in our PAMPA models. According to the membrane compositions, PAMPA models are divided into several types. Creative Animodel provides PAMPA models including but not limited to Table 1.
Table 1. PAMPA models provided by Creative Animodel
|Assay||Model||Phospholipid constituents*||Organic solvent|
|DOPC-PAMPA||Synthetic phospholipid||2% Dioleylphosphatidyl choline||n-Dodecane|
|BBB-PAMPA||Blood brain barrier||2% Porcine brain lipid extract (PC, PE, PS, PI, PA, cerebrosides)||n-Dodecane|
|Egg-PAMPA||Lecithin||10% Egg lecithin, cholesterol||n-Dodecane|
|DS-PAMPA||Double sink||20% Phospholipid mixture (PC, PE, PI, PA, triglycerides)||n-Dodecane|
|BM-PAMPA||Biomimetic||0.8% PC, 0.8% PE, 0.2% PS, 0.2% PI, 1% cholesterol||1,7-Octadiene|
|*PC, phosphatidyl choline; PE, phosphatidyl ethanolamine; PS, phosphatidyl serine; PI, phosphatidylinositol; PA, phosphatidic acid.|
Creative Animodel has a team of experts in the field of pharmacokinetics. Besides demonstrated assays on our website, we also provide customized services to meet your specific needs. If you have any questions about our services, please feel free to contact us.
1. Mannhold, R.; et al. Pharmacokinetics and metabolism in drug design. John Wiley & Sons. 2012.
2. Bujard, A.; et al. HDM-PAMPA to predict gastrointestinal absorption, binding percentage, equilibrium and kinetics constants with human serum albumin and using 2 end-point measurements. European Journal of Pharmaceutical Sciences. 2017, 97: 143-150.
3. Gad, S.C. Preclinical Development Handbook: ADME and Biopharmaceutical Properties. A John Wiley and Sons. Inc, Hoboken, New Jersey, 2008.