Studies of cocaethylene (ethylcocaine) formation by human tissues in vitro.

The potential for different human tissues to form cocaethylene (ethylcocaine) (EC) was evaluated by incubation of homogenates of brain, kidney, liver, lung, and placenta in vitro with cocaine (COC) and ethanol. Only liver yielded measurable concentrations of EC over time, accompanied by a decrease in COC concentration. Although mouse kidney has been reported to produce EC in similar experiments, in the present studies human kidney did not. Interestingly, incubation of human liver homogenates with EC and methanol yielded COC, with a concurrent decrease in EC concentration. This suggests that previously described hepatic esterases can catalyze the transesterification of both EC and COC.