Delivery of certain classes of drugs such as peptides creates problems in transportation across cell membranes and subsequent diminished bioavailability. To overcome this barrier, permeability enhancers can be used to aid the passage of drug across cell membranes. To assess the permeability enhancing activity of Ziziphus jujuba, an aqueous extract of seeds was compared to two members of a known series of permeability enhancement agents belonging to the alkylglycosides. Cell culture systems were observed after transepithelial electrical resistance (TEER) recorded the results of application of the three agents and changes in cell monolayer resistance. Lowering of resistance across a cell monolayer is an indication of either the opening of tight junctions and/or the fluidization of cell membranes. The Z. jujuba extract lowered cell resistance more rapidly in a given time period than the alkylglycosides and allowed full recovery of cells in a relatively short time period. It appears that the extract of Z. juj...