In the area of drug delivery, various polymers are involved. The earlier polymers
were natural in origin. The natural polymers were found to be fraught with many formulation
problems such instability, irreproducibility, changes in aesthetics on storage, uncontrollable
formulation characteristics, etc. As a result new designer molecules were sought for to solve
some of the problems. Some of the natural polymers were largely polysaccharide gums such
as acacia, guar, xanthan, agar, tragacanth, etc. These may have their origin plant, seaweed or
even fungi. Some bacteria are known to produce polysaccharides that may be useful in
medical and pharmaceutical practices. A few polymers may be of animal origin such as
gelatin, serum albumin, liposomes, etc. On the other hand, synthetic polymers are either
modified from natural polymers or completely synthesized from synthetic monomers. They
process properties that seem to relatively address the problems of instability, irreproducibility,
changes in aesthetics on storage, uncontrollable formulation characteristics. The environment
of use in the body is often considered in the preparation of these polymers. Good examples
are the derivates of the acrylic resins, vinyl polymers, cellulose polymers, etc. Various aspects
of these two classes of polymers are presented in this chapter.
