The role of ecgonine methyl ester in the interpretation of cocaine concentrations in postmortem blood.

A study of the metabolism of in vivo cocaine (COC) and the stability of in vitro COC suggests that the presence of benzoylecgonine (BE) in unpreserved blood arises from in vivo COC metabolism and that ecgonine methyl ester (EME) in unpreserved blood arises from in vitro COC hydrolysis. Postmortem cases positive for COC were studied to determine if molar concentrations of EME in unpreserved blood could be used to estimate the blood COC concentration at the time of death when added to the molar COC concentrations. COC was analyzed in 10 postmortem blood specimens between 1 and 8 days following death and again 10 to 70 days after further storage. The COC lost was accounted for by its hydrolysis to EME. Good correlation (r = 0.9677, p < 0.001) was observed when the blood COC concentrations in postmortem cases were compared to blood COC concentrations predicted by the addition of blood COC and EME concentrations; hence, analysis for EME and estimation of perimortem COC concentrations can assist in defining deaths associated with COC use.