Table II.
Advantages and Limitation of Permeability Assays
| In situ perfusion | |
| Advantages | Closest to in vivo anatomy; retains blood flow and innervation; assay requires surgery and anesthesia; low throughput |
| Limitations | Animal usage; not a screening tool |
| Ex vivo tissue diffusion | |
| Advantages | Retains gut architecture; regional differences; human or animal tissue; mechanistic and directional transport |
| Limitations | Limited tissue viability; suboptimal stirring conditions |
| In vitro cell monolayers | |
| Advantages | Transcellular and paracellular passive diffusion, active transport, and efflux; mechanistic studies; human or animal cell lines; can be automated |
| Limitations | Inter-laboratory variability due to culture conditions; labor-intensive; low expression of transporters; lack of mucus layer |
| Artificial membranes | |
| Advantages | Relatively simple and high throughput; can be automated; tolerates wider pH ranges and higher solubilizer concentrations |
| Limitations | Transport dependent upon lipid composition and pH; membrane retention of lipophilic compounds; no active transport |