Acetoacetic acid ethyl ester (1) is hydrolyzed in mammalian organisms by unspecific esterases to ethanol (3) and acetoacetic acid (2). Acetoacetic acid (2) is a normal intermediate metabolite of cells from fatty acid metabolism and can therefore be totally degraded. If present in higher concentrations in the cell, a reversible reduction of acetoacetic acid (2) to 3-hydroxybutyric acid (4) as well as a decarboxylation to acetone (5) is possible. The same metabolic pathways are probably present in microorganisms.
Further degradation of acetone (5) see metabolism page of acetone. Further degradation of ethanol (3) see on metabolism page of ethanol.