Fully automatic flow-based device for monitoring of drug permeation across a cell monolayer

eng] A novel flow-programming setup based on the sequential injection principle is herein proposed for on-line monitoring of temporal events in cell permeation studies. The permeation unit consists of a Franz cell with its basolateral compartment mixed under mechanical agitation and thermostated at 37ºC. The apical compartment is replaced by commercially available Transwell® inserts with a pre-cultivated cell monolayer. The transport of drug substances across epithelial cells genetically modified with the P-glycoprotein membrane transporter (MDCKII - MDR1) is monitored on-line using Rhodamine 123 as a fluorescent marker. The permeation kinetics of the marker is obtained in a fully automated mode by sampling minute volumes of solution from the basolateral compartment in short intervals (10 min) up to 4 hours. The effect of a P-glycoprotein transporter inhibitor, verapamil as a model drug, on the efficiency of the marker transport across the cell monolayer is thoroughly investigated. The analytical features of the proposed flow method for cell permeation studies at real time are critically compared against conventional batch-wise procedures and microfluidic devices