Caco-2 assays measure the ability of a drug to be absorbed from the gastrointestinal tract and thereby to evaluate whether the drug can be suitably dosed via an oral route. It also provides information regarding the ability of a compound to serve as a substrate for the P-glycoprotein (Pgp) efflux drug pump.
Caco-2 cells are intestinal epithelial tumor cells that form a polarized monolayer, a well-defined brush border on the apical surface and intercellular junctions when plated on a semipermeable membrane in a Transwell® dish.
Movement of compound added to the upper chamber of the dish to the bottom of the dish (A – B) measures absorption, while movement of compound added to the bottom chamber to the upper chamber (B – A) measures active transport. A ratio of the B - A rate divided by the A – B rate of greater than two often indicates active transport which may be inhibited by the addition of verapamil, a Pgp inhibitor.
Sample Requirements: 10 mM DMSO stock
Typical Assay Conditions
- 5 μM compound
- Propanolol, nadolol, and quinidine control compounds
- Verapamil (50 Micromolar) – Pgp inhibitor
- Results: Papp (cm/sec) and an efflux ratio