The pharmacokinetics of alternative insulin delivery systems

Limited progress has been made toward developing safer and more acceptable methods for the administration of insulin treatment, despite several attempts to replace subcutaneous injection with alternate routes of administration. Attempts to develop methods for pulmonary administration have demonstrated promise, but have been met with little patient acceptance thus far, while potentially more attractive routes, such as nasal, oral or transdermal administration, have been mainly unsuccessful in providing sufficiently favorable pharmacokinetics and bioavailability for clinical use. The use of enhancers and/or enzyme inhibitors transiently increases absorption across the epithelia of the oral and nasal cavities and the mucosa of the gastrointestinal tract; however, absorption appears to be highly variable, overall bioavailability remains low, causing the cost of goods to be high, and the long-term safety of additives and insulin as a potential local growth factor is not well characterized. While research in some areas of alternative insulin delivery is ongoing, the continued refinement of subcutaneous injection devices and new pharmacological strategies for patients with type 2 diabetes may reduce the need for delivering exogenous insulin and, thus, for alternate administration routes.