ABSTRACT
Polymers have been extensively studied as drug delivery vehicles, especially for anticancer drugs. This chapter discusses some basic principles and examples of polymeric delivery systems. Polymeric delivery systems modify the biodistribution of drugs and localize them to the tumor due to anatomical and physiological differences between normal and tumor tissue. However, substitution of drugs along the polymeric carrier may prevent formation of enzyme-substrate complexes and result in the inability of a normally biodegradable macromolecule to be degraded into easily eliminated fragments. Formation of micelles may affect the biodistribution and the efficacy of the polymeric conjugate. Use of targeting moieties can increase the specificity of polymeric conjugates for tumor tissue. Subcellular targeting can be achieved by attaching specific localization sequences to the polymeric drug conjugate. Incorporation of targeting moieties in the structure of the polymer-drug conjugate can also be done using strategies similar to polymer-analogous or copolymerization reactions.
