Polymers as drugs

Polymeric drugs are defined as polymers that are active pharmaceutical ingredients, i.e., they are neither drug carriers nor prodrugs. In general, the underlying concept behind these therapeutic agents is the utilization of high molecular weight and functional characteristics of polymers to selectively recognize, sequester, and remove low molecular weight and macromolecular disease causing species in the intestinal fluid. The high molecular weight nature of these therapeutically relevant polymers makes them systemically non-absorbed, thus providing a number of advantages including long-term safety profiles over traditional small molecule drug products. Furthermore, multiple functional groups in the polymers incorporate polyvalent binding interactions that can result in pharmaceutical properties not found in small molecule drugs. This article summarizes some of the most recent efforts for the discovery and development of polymeric drugs that have proceeded from discovery phase to market place. Examples include sequestration of low molecular weight species such as bile acids, phosphate, and iron ions as well as polyvalent interactions to bind toxins, viruses, and bacteria as well as polymeric enzyme inhibitors and fat binders as anti-obesity agents. Furthermore, use of functional polymers to treat autoimmune disease and sickle cell anemia has been reviewed.