Investigation and method optimization for the determination of pazopanib and related stress degradation compounds

Cancer is a class of fatal diseases in which a group of cells display the traits of uncontrolled growth, invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis. It is the second cause of death after heart and vascular diseases in death statistics of developed countries. Renal-cell carcinoma accounts for 2 percent of all cancers and accounts for 80 to 85 percent of malignant kidney tumors, with the highest rates in developed countries. Renal-cell carcinoma which is rapidly progressive, are considered to be the highest mortality rate of the disease among urological tumors. With better understandings on molecular biology of renal cell carcinoma (RCC) in recent years, a lot of ways of molecular therapy in late phase/metastasis cases are discovered. Consequently, RCC therapy evolved dramatically in recent years and targeted therapies are evolving too, rapidly. Pazopanib, is one of the inhibitors of protein kinase, is a therapy agent approved by FDA in October 2009. It is used in progressive biologic therapies or in late phase and metastatic renal cancer therapies. This medicine shows its effect by prohibiting activities of proteins causing enlargement and metastasis of cancer cells. Impurity profile and study of a drug substance is very important for safety assessment and manufacturing process. Stress tests are carried out for being informed about decomposition products in forced conditions. No such kinds of works related to analytical determination of degradation products of pazopanib are found in the literature. Therefore a reliable and useful method is needed for pazopanib and other corresponding compounds. In this study, pazopanib used is in treatment of renal cancer, which is serious among cancer tips and obverted in our country, and its degradation products will be determined using LC-MS/MS methods. For this purpose, stress tests are performed under acidic, basic, oxidative, thermal and photolytic conditions for the studied substance. Based on the m/z values and ionization particles, degradation mechanism can be proposed from LC-MS method and products will be determined quantitatively. Moreover, determination of parameters required for the analyses of binary mixtures of pazopanib and internal standard by LC method and performing analyses using these parameters were also performed. Optimization of the analysis conditions varying from the column flow rate of mobile phase, temperature, pH, wavelength and mobile phase composition are performed. It was also aimed performing quantitative analyses using rapid, sensitive HPLC method in order to validate the LC method and application of the method to be developed to pharmaceutical dosage forms.