Once in the bloodstream, 94–98% of alcohol is eliminated by metabolism, and the remaining fraction is eliminated by excretion, which is unchanged (Figure 2). While the vast majority of ethanol metabolism occurs in the liver and its coordinated action with the gastrointestinal tract (105), alcohol is also metabolized in the brain. In both sites, ethanol metabolism is prioritized over other carbon sources to provide energy (90, 106). Although brain metabolism does not significantly contribute to the inter-individual variation in BAC following alcohol ingestion, it is clinically significant due to its acute effects on behavior, reward, and metabolic dyshomeostasis. Additionally, less than 1% of the systemic alcohol undergoes non-oxidative metabolism (107). Despite its small contribution, this section includes a discussion on non-oxidative pathways because the resulting metabolites are of clinical importance (108, 109).
