Pharmacokinetics in cancer chemotherapy

A review of some of the significant issues, such as the host and tumor factors that determine drug concentrations in tumors and the relationship of pharmacokinetics with cancer chemotherapy is presented. The review focuses on issues such as primary and metastatic tissues, penetration of drugs into various layers of a tumor, importance of metabolism in the effects of drugs, cellular and intracellular transport of antitumoral drugs and drug resistance. Studies in animals have revealed that blood concentrations of antitumoral agents are sometimes unable to predict their concentrations in tissues in tumors and the concentrations of antitumoral agents in normal tissues are higher than in the primary tumors. It is also observed that metabolism leads to the formation of inactive metabolites and the metabolic steps involved in the inactivation of anticancer agents is important to find inhibitors to increase their availability in neoplastic tissues.