ABSTRACT
The idea of drug targeting to a specific site in the body, was first introduced almost a century ago by Ehrlich [1]. However only in recent years has the field emerged as an important area of research. This long silence in the field through most of the twentieth century can be attributed to an inadequate understanding of various diseases; a lack of a detailed description, at the cellularmolecular level, of how drugs are processed; and difficulties in identifying and producing carrier molecules specific to the targeted organs, cells, or tissues. The recent advent of recombinant DNA technology and progress in biochemical pharmacology and molecular biology have not only provided a clearer elucidation of pathogenesis of many diseases and identification of various types of surface cell receptors, but also enabled the production of several new classes of highly potent protein and peptide drugs (e.g., homo-and heterologous peptidergic mediators and sequence-specific oilgonucleotides) [2]. For these new drugs, and for some conventional drugs (e.g., antineoplastic agents) that have narrow therapeutic windows and require localization to a particular site in the body, it is essential that they be delivered to their target sites intact, in adequate concentrations, and in an efficient, safe, convenient, and cost-effective manner. Most drug therapies currently available provide little, if any, target specificity. The selective delivery of drugs to their pharmacological receptors should not only increase the therapeutic effectiveness, but also limit side effects and increase safety.
