Hydrogel - A novel drug delivery system

Abstract

Hydrogels, by nature, are water swollen crosslinked networks of hydrophilic homopolymers or copolymers. One of the many distinct characteristics of hydrogels is their ability to change shape in response to an external environment, which acts as the stimulant. Hydrogels, which possess memory, are capable of altering their shape in response to an external environment. Hydrogels with this attribute are termed 'intelligent' polymers. Controlled delivery studies have shown that such external stimuli as pH, temperature and pH/temperature have provided an excellent means of drug delivery from hydrogels. The gastrointestinal tract is an example in which the release of the drug can be site-specific depending on the pH sensitivity of the hydrogel. Utilization of intelligent hydrogels in drug delivery as well as in the biomedical field is of particular interest for this type of material. Various works have been done in the PEG hydrogels, PVA hydrogels, carbopol hydrogels, pectin hydrogels, dextran hydrogels, polylactides hydrogels, polycarbophil hydrogels, etc.