The only available FDA-approved systemic treatment to eliminate active fungus from the hair follicle is ItrafungolTM (itraconazole oral solution), a 10 mg/mL cherry-caramel flavored formulation.4 Itraconazole, a triazole antifungal, acts on the fungal cytochrome P450 enzyme 14 α-demethylase, blocking ergosterol synthesis in the fungal cell membrane and leading to structural degeneration of the fungal organism.2 Itraconazole is highly lipophilic, so the medication accumulates at high levels in sebum for distribution across the skin and to the hair.2,5 It has been found to persist in the skin for up to 4 weeks in humans, allowing weekly pulse dosing.2,5
Prior to the introduction of Itrafungol, compounded itraconazole was available for veterinary use. However, compounded formulations of itraconazole have inappropriately low bioavailability in some species, leading to non-therapeutic plasma concentrations, and are not recommended in veterinary patients.6,7 Itrafungol is administered (5 mg/kg once daily on alternating weeks for 3 treatment cycles) using the dosing syringe included in the package.8
Itrafungol effectiveness was demonstrated in a placebo-controlled laboratory study of 80 experimentally infected cats that did not receive any topical treatment. Within 1 week after the start of treatment, lesions had improved in the Itrafungol-treated cats. After 3 weeks, over 90% of cats in the treatment group reached clinical, but not culture, resolution. By the end of the 9-week study, 90% of treated cats had a least one negative fungal culture.8
Topical antifungal therapy is recommended in order to disinfect the patient’s hair coat, minimize environmental contamination, and shorten the total treatment time as compared to systemic antifungal treatment alone. Common topical products include lime sulfur leave-on rinse and chlorhexidine/miconazole formulations.1,2 Environmental decontamination is also important to minimize false-positive culture results. Effective cleansers for non-porous surfaces include diluted household bleach (1:10 to 1:100 concentration), accelerated hydrogen peroxide, and one-step cleaners with labeled effectiveness against Trichophyton spp. Carpets can be disinfected with vacuuming to remove infective hairs, followed by 2 washes with a beater brush carpet shampooer or hot water extraction. Laundry can be disinfected through 2 washing cycles at any temperature, as long as the washer is not overly full; bleach is not necessary.2
Please examine references 2 and 3 for further discussion of dermatophytosis diagnosis and treatment.