For the drug to get excreted into urine or bile it has to undergo a series of transformation which is called biotransformation. This process alters the lipophilic drugs to a polar object i.e. hydrophilic and is readily absorbed by body. With the addition of functional group in the 1st phase which included oxidization, reduction, hydrolysis etc. Than by undergoing synthetic phase i.e. addition of endogenous compounds, which make them readily absorbed. While most of the drug metabolism is carried out in liver, some tissues, intestine also have enzymes to undergo the process.
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. It is possible for a review to be peer-reviewed, and it is possible for a review to be non-peer-reviewed.
Last date updated on September, 2014