Model Barrier Affecting Drug Transport

With a view to establishing a method to investigate the effect of various barrier on the transport of drugs, a transport cell was devised which consisted of three compartments A, B and C partitioned with two semipermeable cellulose membranes, the central compartment B being thin and keeping a solution of non-permeable 3rd compornent as the model barrier to drug transport, and discussions were made on the relationship among the whole permeability constant, P, the permeability constant through the partitioning membrane, Pm, and the transport constant through compartment B, P*. Then, the experimental examination was performed on the transports of barbital and benzoic acid through the central compartment solution of polyvinylpyrrolidone (PVP). The transport cell devised was useful enough to obtain satisfactorily reproducible results. NaCl which was added in compartment C to make isotonic in the whole system gave no notable effect on the flow of drug. The reasonable results were obtained regarding P, Pm and P*. Analyzing the obtained values of P* on the assumption that the interaction between drug and PVP might be expressed by a Langmuir type isotherm, a quantitative indicator was given to the extent of the above interaction in kinetical process. As a result, the interaction of PVP-benzoic acid was greater than that of PVP-barbital in the present system.