Toxic kinetics is defined as the passage through the body of a toxic agent or its metabolites ,Toxicokinetics is the study of systemic exposure during toxicological experiments. The objective is to quantify the systemic exposure and potentially relate that to toxicology findings. The comparison of toxicology exposure parameters to therapeutically effective exposure parameters gives rise to the idea of a therapeutic window, or the space between efficacy and toxicity. This is depicted in a theoretical example below. Review articles are the summary of current state of understanding on a particular research topic. They analyze or discuss research previously published by scientist and academicians rather than reporting novel research results. Review article comes in the form of systematic reviews and literature reviews and are a form of secondary literature. Systematic reviews determine an objective list of criteria, and find all previously published original research papers that meet the criteria. They then compare the results presented in these papers. Literature reviews, by contrast, provide a summary of what the authors believe are the best and most relevant prior publications. The concept of "review article" is separate from the concept of peer-reviewed literature.