ABSTRACT
Although the pharmaceutical industry has been successful in discovering many new cytotoxic drugs that are potential candidates for cancer treatment, cancer remains a leading cause of death and is a serious threat to human health. Current anticancer drug therapy results in systemic side effects due to nonspeci c uptake by normal, healthy, noncancerous tissues. Many anticancer drugs have marginal selectivity for malignant cells because they target the replicative apparatus in cells with high proliferation rates. Thus, anticancer drugs having the same mechanism of action also have high toxicity against rapidly dividing normal cells [1,2]. Additionally, the side effects associated with chemotherapy limit the dose or cumulative doses that can be administered to patients, which can lead to relapse of the tumor and often to the development of drug resistance [1,2]. Therefore, there have been numerous investigations aimed at developing more ef cient systems that improve selective toxicities against cancer cells, that is, therapies that increase ef cacy and decrease side effects, resulting in an increase in the therapeutic indices of the anticancer drugs. A successful approach is to use particulate drug carriers to alter the pharmacokinetics and biodistribution of anticancer drugs. Nanoparticle drug carriers can be delivered to speci c sites by size-dependent passive targeting or active targeting. Recently, tumor-targeted delivery systems using nanoparticles have become increasingly used in chemotherapeutic engineering of cancer treatments. In the rst part of this chapter, we present a short introduction of nanoparticle systems as drug carriers. This review also provides current approaches used in design and optimization of tumor-speci c drug delivery systems.
