TRANSIL Membrane Binding & Permeability Assays
TRANSIL Membrane Binding & Permeability Assays
Drug transport can broadly be divided into transcellular and paracellular processes. Transcellular movement, which involves the passage of drugs through the cells, is the most common router of drug transport. However, a small fraction of highly polar or very small drugs are able to utilize the paracellular route between the cells.
While a drug’s size, it’s lipophilicity and charge influence its ability to passively diffuse through membranes, diffusion is also influenced by the drug’s structure and in particular its structure-structure interactions with the membrane.
Moreover, increasing a drug’s lipophilicity is not necessarily increasing its propensity to traverse through cell membranes. In fact, the higher a drug’s affinity to the membranes, the more likely it is to enter the membrane and not come out again. That means that drug can get effectively trapped in the membranes – a phenomenon well known as brain tissue binding or microsomal binding. This also has toxicological consequences as the compound accumulates the bodies tissues.
- Assays based on natural membranes of total (e.g. brain or liver extracts, Egg-PC)
- Advantages of vesicles
- True membrane
- Natural fluidity
- Added advantages through beads
- Long-term stability (>3 years)
- Convenience
- Fast and easy to use assay kit
- No preparation required, ready-to-use assay kits
- Build-in quality control
- Suitable for high throughput screening
- Data analysis spreadsheet provided
| Comparison | TRANSIL | PAMPA | Caco-2 |
|---|---|---|---|
| Membrane | Phospholipid bilayer | Organic solvent | Cell monolayer |
| pH | 1 – 11 | 4 – 8 | 6.6 – 7.4 |
| Mechanism | Passive | Passive | Passive, active, metabolism |
| Separation | Fast | Slow | Slow |
| Quality control | Internal | Add. experiment | Add. experiment |
| Manpower | 0.15 FTE | 0.35 FTE | 2 FTE |
Transil Microsomal Binding Kit (MB)
The TRANSIL Microsomal Binding kit measures the affinity of drugs to human microsomal membranes and determines microsomal binding in stability incubation experiments. This allows the accurate estimation of intrinsic clearance from stability incubations by correcting the experimental clearance with the fraction of drug unbound in the incubation. Internal quality controls provide easy assessment of recovery, experiment and data quality. The kit consists of ready-to-use 96 well microtiter plates. One plate can be used for measuring HSA binding of up to 12 compounds. The assay requires only 5 steps: (i) addition of drug candidate, (ii) mixing and incubation for 12 minutes, (iii) removal of beads by centrifugation, (iv) sampling of supernatant, and (v) quantification of drug candidate.
Transil Membrane Affinity Kit (MA)
The TRANSIL MA kit assesses the affinity of compounds to phosphatidylcholine membranes. The kit consists of ready-to-use 96 well microtiter plates. One plate can be used for measuring HSA binding of up to 12 compounds. The assay requires only 5 steps: (i) addition of drug candidate, (ii) mixing and incubation for 12 minutes, (iii) removal of beads by centrifugation, (iv) sampling of supernatant, and (v) quantification of drug candidate.
