|Pharmacology of a drug can be studied under two subheadings i.e, pharmacokinetics and pharmacodynamics. Pharmacokinetics which deals with study of absorption, distribution, metabolization and excretion which can be briefly described as the study of what the body does to a drug. The two phases metabolism and excretion can be grouped together under the title elimination. 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.