Glucagon administration to the rat via eye drops

DS-1, a modified Quillaja saponin, enhances ocular and nasal absorption of insulin

The purpose of this study was to test DS-1, a modified Quillaja saponin, for its efficacy as an absorption enhancer. Anesthetized rats receiving eyedrops or nosedrops formulated with regular pork insulin in saline showed no hypoglycemic response, indicating no systemic absorption of insulin. However, rats receiving eyedrops or nosedrops formulated with insulin plus 0.025-0.10% DS-1 showed rapid absorption of insulin and a concomitant decrease in serum D-glucose levels. No response was observed following sublingual or buccal delivery of insulin. In conclusion, the modified saponin DS-1 was efficacious at enhancing nasal or ocular insulin delivery at extremely low concentrations. The mechanism of DS-1 action is not yet known.

Systemic absorption of insulin and glucagon applied topically to the eyes of rats and a diabetic dog

Nondiabetic rats were anesthetized with xylazine/ketamine to induce hyperglycemia and systemic insulin absorption from eyedrops formulated with dodecylmaltoside was quantitated by both a decrease in serum levels of D-glucose and an increase in immunoreactive insulin levels. When insulin eyedrop administration was delayed until 60 minutes after the administration of eyedrops containing 0.25% dodecylmaltoside, the enhanced systemic absorption of insulin was maintained, suggesting that dodecylmaltoside had an effect directly on the permeability of the nasal sinus epithelium. When glucagon was formulated in eyedrops or nosedrops containing dodecylmaltoside, systemic absorption of glucagon could be measured in the form of an increase in the serum D-glucose concentration following nasal application, but not after ocular application. Eyedrops containing insulin plus 0.125% dodecylmaltoside were administered to a diabetic dog; a dose of 20 units of regular insulin caused a modest decrease in serum D-glucose concentration and a concomitant increase in serum immunoreactive insulin content. These results provide evidence that peptide drugs such as insulin can be formulated in eyedrops with low concentrations of dodecylmaltoside, a mild nonionic surfactant.