Ketoconazole aromatase inhibition

Inhibition of human aromatase by imidazole drugs has been extensively studied in vitro and in vivo [56, 115-120]. Ketoconazole has been most widely studied due to its widespread clinical use as an orally active broad-spectrum antimycotic and reports of associated gynaecomastia [109]. In vitro, it inhibits the aromatisation of both androstenedione [56] and testosterone [118], but is slightly less effective than AG (for example, K, values with androstenedione as substrate are 6,000 nM for ketoconazole and 4,400 nM for AG [56]). In contrast to AG, ketoconazole has been reported to be a non-competitive inhibitor of aromatase [116], although inhibition of other steroid hydroxylases is apparently competitive in nature [114] some other azoles such as miconazole have been reported to be competitive inhibitors [56]. 

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