Urea (urea) is composed of carbon, nitrogen, oxygen and hydrogen organic compounds, also known as urea (and urine). Its chemical formula is CON2H4, (NH2) 2CO or cn2h4o, molecular weight 60, international generic drug name is carbamide. The appearance is colorless crystal or powder. It is the product of animal protein metabolism, usually used as nitrogen fertilizer for plants. Urea is synthesized in the liver, which is a nitrogen-containing metabolite in the body excreted by mammals. This metabolic process is called the urea cycle. Urea is the first organic compound to be synthesized by synthetic inorganic substances. The theory of vigor was overthrown from now on.