Chronic systemic delivery of insulin through the ocular route.

Eyedrops of 0.25% insulin plus 0.5% BL-9 or Brij-78 were instilled into rabbit eyes twice a day for 3 months. It was found that the efficacy of insulin to lower the blood glucose concentration and the uptake of insulin into the systemic circulation remained the same throughout the experimental period. No allergic responses or local side effects could be detected, indicating that both insulin and permeation enhancers (BL-9 and Brij-78) are safe for instillation into the eyes for long periods of time. It is concluded that chronic administration of insulin and absorption enhancers into the eyes is a feasible method to replace injections for diabetes treatment.