2S,4R ketoconazole or levoketoconazole is the 2S,4R enantiomer of ketoconazole, purified from racemic ketoconazole. Both enantiomers exerts antifungal activity. Ketoconazole activates AhR in gene reporter cell line and dose-dependently induces CYP1A1 mRNA and CYP1A1 protein in HepG2 cells, with enantiospecific pattern, i.e. 2R,4S ketoconazole was much more active as compared to 2S,4R ketoconazole. Levoketoconazole was shown to be a more potent inhibitor than the 2R,4S enantiomer of several enzymes in the steroidogenic pathway (CYP11B1, CYP17 and CYP21). Levoketoconazole was tested for the treatment of endogenous Cushing’s syndrome (Phase III) and type 2 diabetes mellitus (Phase II).

Daiichi Sankyo developed an inhibitor of acyl-coenzyme A:cholesterol acyltransferases (ACAT1 and ACAT2), pactimibe (also known as CS 505). Pactimibe has been used in trials phase II for reducing the progression of coronary artery disease and in patients with atherosclerosis. However, on October 26, 2005, the company made the decision to discontinue all ongoing clinical studies of pactimibe, because of the secondary endpoints that showed a lower effect of the drug on atherosclerosis than the standard of care alone and no beneficial effect on the frequency of cardiovascular events.