Tinea cruris is a prevalent condition with global distribution among humans. Over the recent past, renewed interest has emerged with the development of recalcitrant infections and concern over fungal resistance. Self-treatment with easy to access over the counter topical antifungal and steroid preparations have been implicated as a probable cause of the observed decrease in treatment efficacy. Besides, fungal resistance poses threat of recalcitrant symptoms; newly developed formulations such as luliconazole and underutilized agents like ciclopirox have been found to be beneficial.

Ciclopirox olamine is an older topical preparation with a unique mechanism of action compared to the commonly used allylamines and azoles. Recent studies have demonstrated a number of benefits to ciclopirox therapy. Ciclopirox olamine – a hydroxypyridone derivative, differs in structure and mechanism of action from the other known antifungal agents. This topical antifungal agent was approved by the US-FDA in the year 2004. The drug is available as a topical cream topical; its nail lacquer formulation is also used in for treating onychomycosis, tinea pedis, tinea corporis/cruris, pityriasis versicolor, seborrheic dermatitis, as well as vuvovaginal candidiasis (VVC). 1,2 Hydroxypyridones are the class of topical antifungal agents that have a completely different mechanism of action than other topical antifungals – azoles and allylamines. This drug expresses one of the broadest spectra of antimycotic activity and inhibits nearly all clinically relevant dermatophytes, yeasts, and moulds, including certain frequently azole-resistant Candida species, such as Candida glabrata and Candida krusei. Its combined antifungal and antibacterial activity is of particular advantage in the treatment of macerated tinea pedis and “dermatophytosis complex,” – symptomatic intertriginous fungal affections secondarily infected by bacteria.

Ciclopirox – the active compound, acts as a broad-spectrum antifungal, with additional antibacterial and anti-inflammatory properties. It acts through the chelation of polyvalent metal cations, such as ferric (Fe3+) and aluminum (Al3+). This leads to the inhibition of metal-dependent enzymes – cytochromes, catalase and peroxidase, leading to the disruption of cellular activities like mitochondrial electron transport processes, energy production and nutrient intake across cell membrane. This class of drugs can also alter membrane permeability resulting in the blockage of intracellular transport of precursors.

On the other hand, azoles require longer treatment duration. Ciclopirox is cost-efficient and has less serious side effects and has been efficacious against various strains of fungi causing dermatophytic infections.

Ciclopirox is also effective against azole-resistant Candida species also like C. glabrata, C. krusei, and C. guilliermondii. In addition to its anticandidal efficacy, it expresses an inhibitory effect on Gardnerella vaginalis and Trichomonas vaginalis (vide supra) makes it an obvious choice over azoles in mixed infections of the female lower genitalia.

This agent could aid in encountering the emerging antifungal resistance. Even after more than two decades of frequent use of ciclopirox for tinea, PV and VVC – clinical or in vivo resistance is yet to be reported. Dermatophytes exhibit extremely low potential for developing resistance to ciclopirox, both by biochemical or molecular means. The most accepted reasons behind the inability of superficial fungi (both dermatophytes and yeasts) of mounting or evolving mechanisms to resist this drug are its fungicidal mode of action, unique anti-fungal mechanism and a steep dose-response curve.

Source: In: StatPearls [Internet]. 2020 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554602/ Indian Dermatol Online J. 2019;10(4):481. doi:10.4103/idoj.idoj_29_19