Hi,

I have been working on the in-vitro permeability assay (A to B and B to A) on the Caco-2 model using Corning transwell insert (ref. 3470). I am facing the problem with equilibration of control compounds (Propranolol, atenolol chlorpheniramine, ranitidine, lisinopril, and FITC-dextran) when I am using transwell insert without cell monolayer. Even I don’t have any problem with bioanalytical recovery, NSB, and Mass balance. I got >90% overall system recovery. But I could not get equilibrium of any control marker compound in 90 min incubation of plate without cell monolayer in the water bath at 37 C shaking at 50 rpm. I want to know that this is a normal problem, or 90 min is not enough for reaching equilibrium for all compounds in transwell plate. If anyone has faced the same problem, please share the experience and how to overcome this issue?

Devendra Kumar

Post-Doc. Research Associate,

Department of Pharmaceutical Sciences College of Pharmacy University of Nebraska Medical Center 986025 Nebraska Medical Center USA