Challenges in polymer therapeutics: state of the art and prospects of polymer drugs.

The field of drug delivery has attracted tremendous attention during the last two decades. The principal reason for this attention, and the resulting impact on the advance of the field, is the awareness that substantial improvements over current therapies will likely occur primarily through improved delivery of current and yet to be discovered drugs. This realization arises primarily due to the existence of the many barriers that must be circumvented before a drug molecule will reach its target site within the body. In addition, delivery systems can address and correct problems related to the physical characteristic of a drug, including solubility and stability. Consequently, the technologies currently under development for drug delivery and drug targeting systems will have a tremendous impact on the improvement of novel drug therapies. One particular subset of drug delivery systems, those that are based on synthetic polymers, appears particularly promising . This has lead to the emergence of new field, coined “polymer therapeutics”. Generally speaking, polymer therapeutics refers to the use of a polymer as a component of a pharmaceutical formulation for the purpose of improving drug or gene performance. The array of polymers enlisted for this task is quite broad, and includes polymers, exhibiting inherent biological activity, as well as polymers that can exist in the form of polymer-drug conjugates, polymeric micelles, nanoparticles and polymer-coated liposomes. A growing number of polymer therapeutic agents have been approved by the regulatory authorities in the