Background: In vitro investigations of transcorneal permeation behaviour with new drugs in ophthalmology are mainly carried out using excised corneas taken from slaughtered or experimental animals. Analogous to previously used dermis models, an in vitro model was constructed from porcine corneal cell cultures and the permeation barrier properties were tested and compared with permeation data from excised corneas.
Methods: Epithelial, stroma and endothelial cells were successfully isolated by treatment with various enzymes and a corneal equivalent was created step-by-step which morphologically resembled the original tissue. Five different drug formulations were investigated and pilocarpine hydrochloride was chosen as the model drug. The permeation studies were made with a modified Franz cell and analysis was performed by high performance liquid chromatography. Permeation data from excised corneas and from the cornea construct were compared whereby data obtained with lipophilic preparations did not differ (factor of 1) and those obtained with aqueous formulations were relatively similar (factor of 3-4).
Results and conclusions: The results obtained show that the cornea construct can be used as an alternative to excised corneas for in vitro investigations of ophthalmic drug preparations.