Levoketoconazole is the levorotatory or (2S,4R) enantiomer of ketoconazole,[4][5][6] and it is an inhibitor of the enzymesCYP11B1 (11β-hydroxylase), CYP17A1 (17α-hydroxylase/17,20-lyase), and CYP21A2 (21-hydroxylase).[3][4][6] It inhibits glucocorticoid biosynthesis and hence circulating levels of glucocorticoids, thereby treating Cushing's syndrome.[3][6] In addition to its increased potency, the drug is 12-fold less potent than racemic ketoconazole in inhibiting CYP7A1 (cholesterol 7α-hydroxylase), theoretically resulting in further reduced interference with bile acid production and metabolite elimination and therefore less risk of hepatotoxicity.[6] Levoketoconazole has also been found to inhibit CYP11A1 (cholesterol side-chain cleavage enzyme) and CYP51A1 (lanosterol-14α-demethylase), similarly but more potently relative to ketoconazole.[9]
"Levoketoconazole". Drug Information Portal. U.S. National Library of Medicine.
Clinical trial number NCT03277690 for "A Study to Assess the Safety and Efficacy of Levoketoconazole in the Treatment of Endogenous Cushing's Syndrome" at ClinicalTrials.gov