Polymers have been extensively used during the past years in pharmaceutical technology as excipients and pill coatings. They consist of mainly natural polymers such as cellulose, starch and chitosan to a smaller extent. Synthetic polymers such as poly(ethylene glycol), poly(vinyl pyrrolidone), poly(acrylic acids) and their esters, biopolymers, polyesters like poly(lactic acid, polyhydroxyalkanoates, copolymers and modified natural polymers were also used lately as drug delivery carriers. The use of these polymers aims the increase of the solubility of insoluble drugs and the production of innovative formulations for drug targeted and controlled release formulations. Most of them are used in the form of nanoparticles such as nanospheres, while new systems like liposomes, dendrimers and polymeric hydrogels have been extensively studied. This is because polymers have many advantages compared to other used materials. For example, they have lower density, can be easily formed into any shape, exhibit chemical and biological stability, have good mechanical properties and some of them are easily hydrolyzed and eliminated by the body after performing their role. Also, thermosensitive and pH sensitive polymers have been widely explored. 

Continuous evolution allows developing more sophisticated and complex drug delivery systems designed not only to deliver the drug to defined and pre-selected parts of the human body, but also to interact with the body’s environment and to respond on its changes. Based on the above, it becomes clear that today the contribution of polymers to overcoming chronic problems and to treating diseases is crucial and it can be said that they have contributed significantly to the increase in life expectancy.