|The drugs used in conventional chemotherapy targets both cancerous cells and non-cancerous cells. This makes the treatment of the cancer cells highly ineffective due to excessive toxicities. Various attempts have been made to combat tumors specifically to spare non-cancerous cells .But, cancer cells develop resistance to the conventional chemotherapeutics and the newer molecular approach thereby evading the cytotoxicity. Due to several advantages, nanomedicines can be a promising approach for an effective and specific chemotherapy. Firstly, due to high surface to volume ratio, nanoscale carriers reduce the distribution volume of the drug.
To design an effective nanocarrier, it is important to understand the environment in which a nanocarrier will travel its fate and challenges at different steps. Nanocarriers can only designed correctly with enough information about delivery pathway. Different pathways offer different challenges to a naoncarrier. Targeted drug delivery is the ability to direct any therapeutic agent to desired site of action specifically, with little or no interaction with non-target cells/tissues. âCleverâ delivery system includes the parallel behavior of three components: the targeting moiety, the carrier and the therapeutic drug. Drug-targeting can be an (i) active strategy, which is also referred as receptor-ligand or ligand based targeting or the (ii) passive or physical targeting, which introduces the drug carrier complex into the body that can avoid elimination from bodyâs defense mechanism, retains itself in circulation and reaches to the target site.