Mechanisms of cocaine hydrolysis and metabolism in vitro and in vivo: a clarification.

There is confusion in the literature concerning the mechanisms by which the cocaine hydrolysis product, benzoylecgonine (BE), is formed in vitro and in vivo. Some authors assume that all BE is formed nonenzymatically. This review summarizes evidence that both enzymatic and nonenzymatic mechanisms exist. In vitro BE is produced exclusively by hydrolysis at alkaline pH, as esterases present in blood or serum do not catalyze formation of BE. In vivo BE is formed both nonenzymatically as well as through the action of esterases found in a number of tissues including hepatocytes. The enzymatic mechanism is the predominant one operating in vivo.