Elimination of these metabolites occurs via urinary excretion. Each of these metabolites is further metabolized and then excreted in the urine. Most of the metabolites are excreted in the urine. An important group of enzymes involved in the generation of mutagenic metabolites is cytochrome P450. Toxins that result in acidic metabolites may trigger lactic acidosis. Active constituents include terpenoids and secondary metabolites. These compounds induce stress onto a plant leading to increased production of secondary metabolites. Asteraceae produce secondary metabolites, such as flavonoids and terpenoids. Many bacterial secondary metabolites are toxic to mammals. Sick animals tend to forage plants rich in secondary metabolites, such as tannins and alkaloids. No principal metabolites are detectable in plasma. All of the metabolites of domperidone are inactive as D receptor ligands. This requires knowing the concentrations of the metabolites. Breakdown pathways allow the reversion of these metabolites to ceramide. Ketamine and its metabolites are also conjugated.