Adjustment of blood sugar levels with insulin and glucagon eyedrops in normal and diabetic rabbits.

The ophthalmic solutions of insulin and glucagon plus permeation enhancers, BL-9 and Brij-78, were administered to rabbit eyes to study the systemic absorption of these peptide drugs and their effects to affect the blood glucose levels. When plain insulin eyedrops were given, the blood sugar levels were little affected. When insulin plus permeation enhancers were instilled to the eyes, the blood glucose reduced markedly in both normal and diabetic animals. Although sufficient concentrations of glucagon can be reached with plain glucagon eyedrops, the addition of permeation enhancers increased the systemic absorption of glucagon through eyes markedly. As a result, the blood sugar levels were raised markedly by glucagon eyedrops at much lower concentrations. These results indicate that systemic delivery of insulin, glucagon, and other peptide drugs through eyes is a feasible alternative route to parenteral injection particularly when permeation enhancers are added.