Phosphatidylethanol and Other Ethanol Consumption Markers

The study goal is to account for individual differences in biological variables likely influencing Phosphatidylethanol (PEth) formation to determine the extent to which the investigators can improve their ability to characterize alcohol consumed previously. Investigators propose three experiments that combine: (a) controlled human laboratory studies in vivo, (b) clinical laboratory studies of important enzymatic and biological variables measured ex vivo, and (c) the creation and testing of regression models to predict drinking during a naturalistic observational study using PEth levels and key biological variables identified in the lab. Aim 1 is an in vivo pharmacokinetic study that whereby participants will consume a dose of alcohol to achieve a target blood alcohol concentration of 0.06%. Blood samples will be collected repeatedly during a 6-hour period to characterize blood/breath alcohol concentrations and PEth syntheses. Then PEth elimination half-life will be characterized across a 10-day period while remaining alcohol abstinent outside the lab. In Aim 2, alcohol-free blood collected from Aim 1 will be examined ex vivo to characterize key biological variables (e.g., enzyme activity, red blood cell count, precursor levels) involved in PEth synthesis and elimination. Regression formulas will evaluate these variables for their ability to explain the previously unexplained between-subject differences in the PEth levels formed after the same amount of alcohol is consumed. Finally, in Aim 3, regression equations will be used to evaluate the value of using these biological/enzyme variables to improve (above and beyond that of PEth alone) the prediction of naturalistic drinking self-reported by participants over a 28-day period.