(Greek: metabolites - the convert). Name for the products resulting from a certain active substance by conversion in the body. The conversion process is called metabolism. It can lead both by a linear decay of individual reaction steps up to a stable final product as well as by competitive reaction mechanisms to several intermediate and final products.
In many cases only the formed metabolites are the actually physiological effective substances. Substances, which in vivo (in the body) - or also in vitro (blood or urine sample) - are very fast metabolized, can be analized often only by their final metabolites. For example, Cocaine hydrolyzes rapidly in few hours to Benzoylecgonine and Ecgoninemethylat, which are - stored in cooled fluoride-stabilized blood samples - stable for at least one month.