Metabolic intermediates are formed during the biochemical pathway known as metabolism, which includes two main phases: Phase I and Phase II reactions. In Phase I, enzymes such as cytochrome P450 introduce reactive or polar groups into xenobiotics. This step often involves oxidation, reduction, or hydrolysis. The intermediates formed can then undergo Phase II reactions, where they are conjugated with endogenous molecules, enhancing their solubility for excretion.
