IC50: Ciclopirox ethanolamine, a broad-spectrum antifungal agent, inhibits dermatophytes and yeasts pathogenic with a minimal inhibitory concentration (MIC) of 0.98-3.9 μg/mL.

Ciclopirox ethanolamine, working as an iron chelator, suppresses a substantial number of clinically relevant dermatophytes, yeasts, and molds, including the frequently azole-resistant Candida species Candida glabrata, Candida krusei, and Candida guilliermondii. Moreover, Ciclopirox has been proved to inhibit a wide range of bacteria in humans, including many gram-positive and gram-negative species pathogenic bacteria. [1]

In vitro: Ciclopirox inhibited dermatophytes and yeasts pathogenic with MICs of 0.98-3.9 μg/mL. Studies from C. albicans cells demonstrated that after being rapidly absorbed, Ciclopirox largely accumulated intracellular with a concentration of 200 times greater than those in the medium. High concentration of Ciclopirox resulted in the loss of folin-positive substances and potassium ions, by this way this agent could lead to cellular leakage without breaking the cell wall. Similarly, by decreasing the uptake of precursors of the macromolecules or by decreasing the uptake of essential ions such as potassium ions and phosphate, Ciclopirox blocked the synthesis of protein, RNA, and DNA in growing fungal cells. The chelation of metal ions and the suppression of iron-dependent enzymes were crucial for Ciclopirox to exert antifungal effects. Ciclopirox alone intensively suppressed the growth of Aspergillus fumigatus B5233 conidia. Ciclopirox also exhibited synergistic antifungal effect when being combined used with ketoconazole. [1]

In vivo: The effect of Ciclopirox on endogenous HIF-1 target gene-VEGF was investigated using different animal organ models including mouse skin wound model, rat kidney model and chicken chorioallantoic membrane model. According to the results, CPX functionally activated HIF-1, induced VEGF expression and accelerated angiogenesis. [2]

Clinical trial: A great deal of clinical trials was and still being conducted with Ciclopirox. This agent was first applied for fungal skin infections and vaginal candidiasis, and has been well established in these indications. More recently, Ciclopirox has been clinically explored in seborrhoeic dermatitis and onychomycosis, demonstrating remarkable efficacy and excellent tolerability. [3]

References:
[1]Niewerth M, Kunze D, Seibold M, Schaller M, Korting HC and Hube B.  Ciclopirox olamine treatment affects the expression pattern of candida albicans genes encoding virulence factors, iron metabolism proteins, and drug resistance factors. Antimicrob Agents Chem. 2003 Jun; 47(6): 180517.
[2]Linden T, Katschinski DR, Eckhardt K, Scheid A, Pagel H and Wenger RH.  The antimycotic ciclopirox olamine induces HIF-1 stability, VEGF expression, and angiogenesis. FASEB. 2003 Feb; 17: 761–3.
[3]Subissi A, Monti D, Togni G and Mailland F.  Recent nonclinical and clinical data relevant to its use as a topical antimycotic agent. Drugs. 2010 Nov; 70(16): 2133-52.