Cath Lab Digest

Given the increasing prevalence of tinea pedis, this author discusses the various forms of the infection, reviews the current literature on topical antifungal therapy and offers perspective on the role of OTC topicals in the overall management of tinea pedis.

   The incidence of mycotic infections in the United States continues to rise, especially among older patients.^1,2 The overall prevalence of cutaneous fungal infections has been estimated to be between 10 and 20 percent of the United States population. This reportedly translates into approximately 29 to 59 million individuals who will experience at least one fungal infection in any given year.¹

   The literature suggests that up to 70 percent of the world’s population will experience a cutaneous mycotic infection at some point in their lives.³ Furthermore, 45 percent of those with tinea pedis will have recurrent episodes for more than 10 years.⁴

   Tinea pedis, the most prevalent type of mycotic infection worldwide, is caused by a dermatophyte in more than 90 percent of patients.⁵ Dermatophytes are pathogenic fungi that produce keratinase, a proteolytic enzyme that breaks down skin, hair and nails by its action on keratin.^4,6 The primary organism responsible for causing tinea pedis, both in the U.S. and worldwide, is Trichophyton rubrum.^2,5,6 In a large, four-year surveillance study, researchers identified T. rubrum in up to 82.9 percent of isolates from tinea pedis infections.⁵

   The most common form of tinea pedis is interdigital, which occurs in the web spaces between the toes. Interdigital tinea pedis is characterized clinically by maceration, scaling and itching of the skin. Chronic squamous or papulosquamous tinea presents with a moccasin distribution of dry thick scales and fissuring on the plantar surface. Vesicular tinea appears as small vesicles/bullae on the erythematous bases in the arch, interdigital spaces and other non–weightbearing surfaces. Finally, ulcerative tinea pedis is characterized by maceration, denuded tissue, desquamation and foul odor arising from the process of tissue breakdown.⁷

   Effective management of tinea pedis is aided by patient education on the proper use of available treatment options, as well as proper foot care and hygiene. Topical therapies for tinea pedis are generally associated with fewer adverse effects than systemic antifungals. Therefore, topical therapy remains a first-line therapy for uncomplicated dermal dermatophyte infections.⁴

   A number of topical preparations are now available worldwide over the counter (OTC), making it more convenient for patients to access the products. These available topical OTC preparations may also decrease the overall cost of treatment for some patients. Others may benefit from low prescription co-pays.

   Although high fungal cure rates are achievable with topical therapy when patients use products as recommended, an important concern is that many patients stop applying the medication at the point of symptom improvement and do not continue using the product as directed on the label.^1,4 Patients are more likely to complete a course of topical therapy that involves fewer applications (i.e., less frequent dosing and/or shorter total duration of therapy).

   Completion of the full treatment course is one important factor in preventing recurrent infections. Other factors include the efficacy of the active ingredient against the infecting organism and the topical agent’s ability to prevent reinfection.