An in vitro method simulating drug release from viscous eye drops in rabbit and man

A method has been developed using a diffusion cell in an attempt to determine the drug release from viscous solutions under conditions simulating the blinking movements in the rabbit and human eye. Diffusion coefficients were determined at rest and at different velocities. For the solutions at rest, corresponding with the conditions at the surface of the rabbit cornea, the diffusion velocity decreases with increasing viscosity. When the solution is moved at a velocity corresponding to that of lachrymal fluid at the surface of the human eye, the influence of viscosity may be neglected.