Studies for different ways of insulin delivery have started since the first discovery of insulin. However, desired biological effect of non-parenteral routes has not been achieved, yet. Unfortunately the use of insulin has been limited to parenteral routes due to enzymatic degradation process by mucosal peptidase, mucosal barrier resulting in insufficient absorption and poor permeability throughout the intestinal mucosa. The parenteral route of insulin has been used in different ways including intramuscular, subcutaneous, intravenous and intraperitoneal ways. However, the parenteral route has side effects involving patient's incompliance due to fear of injection, local discomfort including bleeding at injection site, injection pain, lipohypertrophy as well as some disadvantages such as glycemic fluctuation. Alternative routes of non-invasive insulin delivery including oral, nasal, buccal, ophtalmic, rectal, vaginal and transdermal systems have been performed eventhough successful results have not been achived due to the abovementioned barriers. Additionally, recently approved tecnology of insulin delivery through pulmoner route has also been one of the methods aimed at replacing parenteral route. However, recent pulmonary technology of insulin delivery requires higher doses and frequent applications. Furthermore, inhaler insulin is not applicable to smokers and is not used in patients with pulmonary diseases or infections. Today, desired clinical efficacy and safety on the use of non-invasive routes of insulin have not yet been achieved and studies are continuing with newly developed technologies.
Key words: Oral Insulin; Inhaler Insulin; Buccal Insulin; Transdermal Insulin.
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