Smart liquids for oral controlled drug release: An overview of alginate and non-alginate based systems

Sustaining and controlling the rate of drug release is essential in pharmaceutical technology. It can reduce the number of units administered by the patient with subsequent improvement in patient compliance. These technologies can allow controlled liberation of the active pharmaceutical ingredients to correlate with the chronobiology of the diseases. The significance can be hastened if the controlled release technology was adopted in liquid oral dosage form. Numerous approaches have been implemented in development of liquid oral controlled release formulations. These include preparation of sustained release coated microparticles which are fabricated in the form of oral suspension. Application of ion exchange resin showed success with some products available in the market. Alginate based in situ gelling system has gained much interest. This system depends on fabrication of drug in alginate solution in presence of sequestered calcium ions. This system undergoes in-situ gelation immediately after administration due to liberation of calcium ion in the acidic environment of the stomach. The developed gel may be manipulated to float or to perform mucoadhesion. The promise of such technique has been magnified further after combination with chitosan which maintained gel formation in the stomach as well as in the intestinal environment. This article will provide an overview on liquid oral controlled release drug delivery systems with emphasis on the alginate based formulations