Transport across a phospholipid barrier

The transport of two small organic solutes across a phospholipid barrier supported in a Millipore filter has been studied. The flux of penetrant across the barrier has been followed using two different experimental procedures with a rotating diffusion cell. In one approach, the data is analyzed by the normal reduction for rotating diffusion cell experiments; in the other, a new interpretation of the lag-time for transport across the barrier is invoked. The combination of the two analyses allows determination of the diffusion coefficient of the solute in the lipid barrier, the aqueous-lipid partition coefficient of the solute, and the interfacial transfer rate constant for the solute crossing the phospholipid-aqueous phase interface. Comparison of the transport parameters obtained with in vivo percutaneous absorption results is discussed.