Conventional and Nonconventional Approaches to Site-Specific Targeting of Nanotherapeutics in Some Infectious Diseases and Metabolic Disorders

Systemic fungal infection in pulmonary tissue and viral infections affecting peripheral nerve claim millions of lives every year. The inability of therapeutics to reach the diseased sites at an optimum concentration, lack of patient-friendly delivery strategies, and inability of delivery strategies to penetrate and/or release the therapeutic payload at the diseased sites, keeping the normal cells unaffected, are some of the reasons which demand alternative or other methods to successfully deliver drug to affected sites. Since the end of the last century, a novel drug delivery system (drug-nanocarrier system) has reached a new benchmark with the application of nanomedicine in the treatment of fatal metabolic disorders and infectious diseases. Despite its ability to increase permeability and penetrability to cells/tissues/organs, its uncontrolled biodistribution may cause cytotoxicity to nontargeted cells, resulting in improper therapeutic management. Therefore, ligand-based active targeting strategies are most popularly exploited by researchers around the world to develop site-specific targeting of diseased sites. A plethora of site-specific nanomedicines has been developed on the laboratory scale based on conventional active targeting strategies with ligands. Even after a lot of sincere efforts, the translation of laboratory to clinic is very limited due to toxicity, stability, and the nonspecific nature of ligands. Therefore, certain nonconventional approaches of targeting therapeutics, such as gene-silencing technology, management of glioma by incorporation of brain-mimicking lipid in nanoliposomal formulations, chemical-mediated nanoliposomal formulations specifically targeted to peripheral nervous systems (PNS), and innovation of novel delivery devices, offer significant promise for effective therapeutic management. This chapter focuses on the pros and cons and future prospects of various conventional and nonconventional approaches of drug targeting with an insight to develop powerful therapeutic weapons for effective therapeutic management of deadly diseases.