Analysis of the antifungal activity of ketoconazole, zinc pyrithione, and ciclopirox olamine against Pityrosporum ovale. A diffusion assay for cultures in solid media

Background Recently dandruff has been associated with a local increment in the number of Pityrosporum yeasts. Due to this fact, several anti-dandruff shampoos containing antifungals have been marketed. Objective We studied the sensitivity of Pityrosporum ovale (PO) to three different groups of antimycotics (ketoconazole, Zn pyrithione, and ciclopirox olamine). Methods/Results The drugs were tested by an inhibition assay in solid medium. Ketoconazole proved to be the most effective drug in inhibiting PO growth in a dose-dependent fashion. The results of our evaluation revealed that the inhibitory effects of the drugs were ketoconazole > Zn pyrithione > ciclopirox olamine. Conclusion We postulate that the diffusion assay is a reliable medium for evaluating the effectiveness of antifungals contained in anti-dandruff shampoos.