Simulation of methods for drug delivery to the cochlear fluids

The inner ear fluids are remarkably 'unstirred' so that it cannot be assumed that applied drugs are dispersed throughout the fluid spaces. Calculation of the effective concentrations achieved when drugs are applied directly to the inner ear is made possible by simulations combining the physical processes involved in solute dispersal, which are diffusion, longitudinal fluid flow and clearances to other compartments. The approach has been validated in numerous experiments in which ion-selective electrodes were used to characterize the spread of marker substances in the cochlear fluids. The model incorporates the known size and geometry of cochlear fluid spaces for 6 species, including the guinea pig and the human. The simulator allows the dispersal of drugs or other substances to be approximated with knowledge of relatively few parameters. The simulation program is available on the Internet at http://oto.wustl.edu/cochlea/.