GASTROINTESTINAL PATCHES FOR ORAL DRUG DELIVERY -Part 4

As you know, oral drug delivery though attractive compared to injections, can not be utilized for the administration of peptides and proteins due to poor epithelial permeability and proteolytic degradation with in the gastrointestinal tract. Several strategies have been proposed to boost oral insulin bioavailability including permeation enhancers, enzyme inhibitors, encapsulation technologies such as microspheres and nanoparticles, microemulsions and liposomes. These types of methods have shown improved bioavailabilities over the basic liquid formulations. However, the novel strategies found to be more effective when they were applied as GI patches.

The method which utilizes mucoadhesive intestinal patches to deliver therapeutic doses of insulin into systemic circulation is the main application of GI patches. This is more efficient in reducing the blood sugar compared to other routes of administration like sub cutaneous injections. This was proved by some of the studies conducted over the patch systems. But, a design of intestinal patches that allow delivery of therapeutic doses of insulin has yet to be described.

In short, patch systems applied to the GI mucosa are designed to perform multiple functions using the single platform, namely drug protection, unidirectional release and bioadhesion. Now it is proved that these patches can be used for the delivery of large molecules such as the drug- in- adhesive patch for delivery of G-CSF, erythropoietin and interferone- α and insulin patch for oral delivery of insulin. The integration of micro fabrication technology might enable the translation of some of the functions associated with patch systems in to devices on an even smaller scale. In the near future integrated ‘smart’ devices capable of fully autonomous delivery and site specific cell targeting will have a considerable impact on drug administration.

Even then, these patches are not without some demerits, as it was found that systemic bioavailabilty of some drugs are less compared to other mucosal delivery systems like; buccal, nasal, rectal, vaginal etc. Standardization of micropatch particle size is necessary as too small particles may phagocytosed by the macrophages thus may cause localized inflammatory response. Some of the synthetic polymers used as mucoadhesives may cause irritation to the mucous membrane of the GI tract. So selection of the polymer is very crucial in the preparation of GI patches. Further studies are going on for the improvement of GI patch delivery systems to make better oral delivery of the medicaments.