The collagen shield. A new vehicle for delivery of cyclosporin A to the eye.

Collagen shields were tested as a means of delivering the immunosuppressive drug, cyclosporine A (CsA), to the cornea and aqueous humor in rabbit eyes. Gelatinous collagen was mixed with crystalline CsA and then, during drying, was formed into contact lens-shaped shields which were applied to rabbit eyes. The amount of CsA in the corneas and aqueous humor (AH) samples from shield-treated eyes was compared with samples from rabbit eyes treated with CsA in olive oil. CsA concentrations were measured by radioimmunoassay (RIA) at 2, 4, and 8 h after application of the shields or drops. Both the corneal and aqueous humor concentrations of CsA achieved with the shield delivery system were 10-fold higher than those obtained with topical CsA-olive oil drops. The CsA levels achieved in the cornea using the collagen shield are sufficient to inhibit cellular immune reactions in vivo. These results demonstrate that collagen shields may be useful as an ocular delivery system for the drug CsA.