The in vitro properties of a new hydroxypyridone antimycotic rilopirox, with special reference to its anti-Candida activity

In vitro properties of a new hydroxypyridone antimycotic rilopirox (RIL) with special reference to its anti-Candida activities were studied in comparison with the three reference drugs, ciclopirox olamine (CPO), oxiconazole nitrate (OCZ) and isoconazole nitrate (ICZ), using several strains of Candida albicans and Candida glabrata as the test organisms. RIL was potently fungicidal for growing cultures of these Candida strains, whereas all the three reference drugs were slightly fungicidal or fungistatic. Unlike OCZ and ICZ whose anti-Candida activity was decreased by lowering pH or adding serum to culture media, the activity of RIL was scarecely affected by change in pH or serum addition. However, RIL became less potent in the presence of Fe3+ at concentrations of 10(-5) mmol/ml or above. These findings suggest that RIL will be useful as a topical anti-Candida agent.