6'-Epipravastatin is a secondary isomeric metabolite of pravastatin. Pravastatin, one of the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) widely used in the management of hypercholesterolaemia, has unique pharmacokinetic characteristics among the members of this class. The major metabolites of Pravastatin found in plasma, urine and feces are 3′α-isopravastatin, 3′α,5′β-dihydroxy-pravastatin, desacyl-dehydropravastatin, 3′′-hydroxy-pravastatin and 6′-epipravastatin. The major pravastatin metabolites are generated by non-CYP-dependent processes: 3alpha-isopravastatin and metabolite 6-epipravastatin are either formed by acidic degradation of pravastatin in the stomach or by sulfation at the 6’beta-hydroxy group by sulfotransferases, followed by a nucleophilic attack of hydroxy anions at the 3alpha- or 6’alpha-position.

Glycodeoxycholic acid (GDCA), a bile acid, is formed in the liver from chenodeoxycholate and glycine. GDCA was one of twenty-five plasma metabolites, which were significantly different among asthma and healthy controls. Besides, GDCA was elevated in patients with acetaminophen-induced acute liver failure (AALF) and was significantly increased in non-surviving AALF patients compared with survivors. Thus GDCA level could serve as a prognostic biomarker for AALF patients.

Isopilocarpine is a diastereomer of pilocarpine. Isopilocarpine coexists with pilocarpine in nature and is also a degradation product of pilocarpine after oral administration to humans. It can be found in the leaves of some Pilocarpus species. Pilocarpine targets the muscarinic receptors and is approved for treatment of xerostomia. Isopilocarpine is often present in formulations of pilocarpine but has no appreciable effect on muscarinic receptors.