Biopharmaceutics and clinical outcomes of emerging dosage forms of insulin: A systematic review

Background

Many works are ongoing with the aim of obtaining a more convenient way than the parenteral injection for administering insulin.

Purpose

To review the biopharmaceutics and clinical outcomes of the various emerging dosage forms of insulin so as to identify the promising formulations.

Method

A systematic literature search with analysis was carried out to obtain information on the biopharmaceutics and clinical outcomes of the emerging dosage forms.

Results

Intraperitoneal insulin was found to be characterized by direct drug delivery through the portal vein to the liver having bioavailability of 60%, but its clinical application is limited by the high risk of infection. The bioavailability of transdermal insulin has been enhanced using electrical, mechanical and physical techniques; and such formulations could achieve up to 39.5% blood glucose reduction. Oral insulin, known to be the most convenient, has its bioavailability limited to 1% by enzymatic degradation and poor absorption. Its challenges however, have been addressed by various interventions to achieve different levels of bioavailability up to 73.1%. Buccal insulin has shown potentials in managing postprandial hyperglycaemia without posing hypoglycaemic risk but its clinical applicability has not been established; whereas the long transit time, lower levels of peptidases and incorporation of permeation-enhancers have been shown to be responsible for the good treatment outcome of colon-targeted insulin. Rectal insulin with bioavailability of 11% has been shown to be considerably safe but not cost-effective while the ocular insulin is limited by poor absorption. Nasal tolerance and high rate of treatment failures were shown to be limiting intranasal insulin while the pulmonary insulin is being limited by peripheral drug retention and insulin resistance.

Conclusion

The biopharmaceutical profiles and clinical outcomes of transdermal, oral and colon-targeted insulin are superior to those of the other dosage forms. Further research works could be done towards the full development of these promising formulations.