Polymers

Polymers have been used as a main tool to control the drug release rate from the formulations. Extensive applications of polymers in drug delivery have been realized because polymers offer unique properties which so far have not been attained by any other materials. Advances in polymer science have led to the development of several novel drug-delivery systems. A proper consideration of surface and bulk properties can aid in the designing of polymers for various drug-delivery applications. These newer technological developments include drug modification by chemical means, carrier based drug delivery and drug entrapment in polymeric matrices or within pumps that are placed in desired bodily compartments. These technical development in drug delivery/targeting approaches improve the efficacy of drug therapy thereby improve human health. Polymer chemists and chemical engineers, pharmaceutical scientists are engaged in bringing out design predictable, controlled delivery of bio active agents. Biodegradable polymers have been widely used in biomedical applications because of their known biocompatibility and biodegradability. In general natural polymers offer fewer advantages than synthetic polymers. The following review presents an overview of the different biodegradable polymers that are currently being used, their properties, as well as new developments in their applications.

The aim of writing this review is to put a light on the recent trends in development of Drug loaded Beads. Drug loaded beads are gastro retentive drug delivery systems based on multi Unit approach and are prepared to obtain prolonged or controlled drug delivery, to improve bioavailability, stability and target drug to specific sites. These are Spherical in shape and approximately 1.5 mm in diameter. These can be prepared by various methods like ionotropic gelation, hydrogel embedment, solvent evaporation and Melt Solidification by using different polymers. Promising enhancement in bioavailability and site specificity has been achieved by drug loaded beads.

  Mucoadhesive delivery systems were proven to be suitable for the purpose of reduction of transit time of the dosage form through the gastro-intestinal tract, and increasing bioavailability of drug. Buccal tablets of Carvedilol were prepared by direct compression method for using various compositions of combination of Starch: C934 and Starch: HPMCK15M in various ratios. The tablets were evaluated for their characteristics properties, mucoadhesion and in vitro-in-vivo study. All the physicochemical properties were acceptable within the limit. Formulation containing starch and Carbopol 934(E4) showed better bioavailability as compared to tablet containing  Starch and HPMCK15 (F5) and The bioadhesive strength of the formulations containing polymers were in the order of E4> F5. Stability studies were carried out as per ICH guidelines and formulations were found to be Stable.