Cytotoxicity of Tamoxifen-Loaded Solid Lipid Nanoparticles

Breast cancer is one the most important health concerns of the modern society (Ferlay et al., 2007). Worldwide, it is estimated that over one million new cases of breast cancer are diagnosed every year, and more than 400 thousands will die from the breast cancer (Coughlin & Ekwueme, 2009) The life-time risk in women contracting breast cancers is estimated to be 1 in 8, which is the highest among all forms of cancers. (DevCan, 2004). Although the mortality rates from breast cancers have decreased in most developed countries because more frequent mammographic screening and extensive use of tamoxifen, it still remains the second highest in women (Clark, 2008). Breast cancer incidence rates were reported to have doubled or tripled in developing countries in the past 40 years (Anderson et al., 2008; Porter, 2008). The main options for breast cancer treatment include surgery, radiation therapy and chemotherapy (Mirshahidi & Abraham, 2004). Surgical procedures usually lead to significant morbidity such as lymph edema, muscle wasting, neuropathy and chronic pain (Paci et al., 1996). Radiation therapy is useful for cancer which is more localized, but it also carry a number of acute and chronic sideeffects such as nausea, diarrhea, pain and fatigue (Ewesuedo & Ratain, 2003). Endocrine therapy may be used as a supplementary treatment. This method of therapy is applied to specific group of patients, e.g. women after menopause with hormone-responsive disease (Gradishar, 2005). In hormone-sensitive cancer patients receive chemotherapy with cytotoxic drugs. The cytotoxic drugs treat cancers by causing cell death or growth arrest. Effective cancer chemotherapy is able either to shrink a tumor or to help destroy cancer cells (Ewesuedo & Ratain, 2003). A number of obstacles such as drug toxicity, possible undesirable drug interactions and various forms of drug resistance have to be overcome to achieve effective chemotherapy (Cardosa et al., 2009). Drug resistance is a general problem in the chemotherapy of several cancers including breast cancers (Wong et al., 2006). Failures in treatment of cancers are common. Development of new drugs is also slow to progress. Among the reasons contributing to this are weak absorption, high rate of metabolism and elimination of drugs per oral administration resulting in less or variable concentrations in blood, poor drug solubility, unpredictable bioavailability of oral drugs due to food, and tissue toxicity (Sipos et al., 1997). Thus alternative methods of drug administration like appropriate drug carrier system is needed to overcome this problem. Depending on the route of administration, the size of