Cocaethylene as a biomarker to predict heavy alcohol exposure among cocaine users.

Background: Cocaethylene (CE) is a cocaine metabolite formed during alcohol and cocaine co-consumption. There are no previous studies to assess the effectiveness of hair CE as a biomarker indicating chronic alcohol consumption among individuals who have consumed cocaine.

Objectives: To establish the ability of CE to predict chronic alcohol use among individuals testing positive for cocaine.

Methods: We studied all cases referred to our laboratory where both chronic cocaine and alcohol consumption were sought, and values of hair cocaine, benzoylegconine (BE), CE, and FAEEs (as marker of chronic alcohol consumption ) were available. Cocaine, BE and CE were screened by ELISA and confirmed using headspace-solid phase microextraction (HS-SPME) and GC-MS. FAEE were analyzed using HS-SPME and GC-MS/EI. Sensitivity, specificity, and predictive values of CE as a marker of alcohol consumption among cocaine users were calculated using different FAEE cutoffs.

Results: Cocaine (P<0.001) and BE (P<0.001) concentrations were associated with increased FAEE. The positive predictive value of CE to identify alcohol consumption was 0.66 for excessive drinking and 0.76 for chronic drinking among positive cocaine users. Negative CE ruled out almost completely excessive alcohol consumption.

Conclusion: Positive hair CE results had high specificity for chronic excessive alcohol consumption among cocaine users. With no established safe level of alcohol in pregnancy, identification of CE in hair of pregnant women who have used cocaine can serve as a biomarker for fetal alcohol spectrum disorder.