Nano drug delivery systems: Targeted and site specific tool for therapeutic management

It is well known that the main goal of drug delivery is effective and safe delivery of a drug to its target tissues, organs and cells. However, transport of a drug to its specific targets represents one of the major challenges for an effective drug delivery (Mainardesand Silva, 2004). Conventional enteral or parenteral drug delivery methods of systemic drug administration include the formulation of a drug into suitable dosage forms for oral/gastrointestinal administration (e. g. tablets, capsules, solutions, suspensions, syrups, etc.) or sterile drug preparations (solutions, suspensions, emulsions, or reconstituted lyophilized powders) suitable for administration by injection (intravenous, epidural, intramuscular, subcutaneous, etc.) (Robinson and Mauger, 1991). Nevertheless, these systemic drug delivery methods are associated with several limitations such as relatively low site specific bioavailability of administered drugs, unfavorable distribution of drugs throughout the body and, in most cases, low accumulation in the target site, adverse side effects, etc. (Bardal et al., 2011). Besides, these drug delivery systems can't fulfill the ever-growing need of the modern medicine such as personalized medicine and targeted therapies. Therefore, there was an urgent need to develop novel drug delivery systems for localized and targeted delivery of therapeutics. Over the decades, researchers have extensively studied development of carrier-based drug delivery systems with truly targeted features towards specific disease as well as to prevent drug degradation, resistance, drug side effects and also improve the potential of individualized medicine. Various surface markers and cytokines such as integrins, folate, growth factors etc., which are known to express on disease cells and their microenvironments, were explored for developing counter marker functionalized drug carrier to recognize the target disease cells. Carrier-based targeted and localized drug delivery systems, e.g. supramolecular gels (Oneto et al., 2016), nanocarriers such as different types of nanoparticles (Garbuzenko et al., 2014; Chen et al., 2010), liposomes (Zhang et al., 2012; Saad et al., 2008), Nano drug delivery systems: Targeted and site specific tool for therapeutic management