Emerging Concepts In Treating Onychomycosis
Given the significant prevalence of onychomycosis that podiatrists see in practice, these authors review current treatments and offer a closer look at emerging topicals, orals and devices that may hold promise in treating this disease.
Since the drug companies’ fungal wars of the 1990s, many podiatrists have lost interest in the treatment of onychomycosis and have settled into their own particular treatment paradigm. However, emerging technologies and new drug delivery systems have again brought the treatment of onychomycosis to the forefront of our profession.
Onychomycosis is still the number one disease diagnosed and treated by podiatric physicians in the United States.1 While researchers have estimated that 2 to 3 percent of the U.S. population has onychomycosis, this number seems dynamic and growing with time as the infection spreads in a pandemic fashion. Onychomycosis currently affects up to 20 percent of individuals between 40 and 60 years old. Thirty-two percent of individuals 60 to 70 years old have it and over 50 percent of those over the age of 70 are infected.2,3
Army research from 1965 stated that fungus is contagious to others and can also spread to other locations in the patient’s own body. Nail trauma and longer exposure to fungus contribute to higher infection rates. Still, many clinicians wonder why certain patients acquire fungal infections and others do not. Some researchers have postulated that an autosomal gene defect produces an immune sensitivity that allows infection.1,3
The infection of the nail may be caused by dermatophytes, saprophytes and/or Candida. Most studies suggest Trichophyton rubrum is the most common organism.
The nail is made up of three layers. The nail plate acts as a button, opposing the force that places pressure on the finger or toe. This increases the discrimination ability of the acral pulp and skin wherever the skin feels the object. When a fungal infection occurs, the intermediate layer hypertrophies and distorts the nail. Since the ventral layer stays intact, the nail is usually still attached to the nail bed by a specialized onychodermal band known as the sole horn.4-6
The treatment of onychomycosis centers on five basic modalities: debridement, surgical removal, topical medications, oral medications and emerging technologies.
What You Should Know About Debridement And Surgical Options
For podiatric physicians, debridement of the fungal nails is a common practice, one that many other specialists overlook. Although debridement does not treat the infection, it can decrease the fungal load of the nail and can complement medical therapy. It can also reduce pressure necrosis and improve the nail’s overall cosmetic appearance.7
The treatment is noninvasive and is therefore safe for all patients, including those with advanced peripheral vascular disease and diabetes. Another debridement technique other than use of the nail nipper is 40% urea. Over time, the urea eats away at the keratin, providing chemical debridement of the nail area.8
Surgical removal of the nail by matrixectomy can be effective in eliminating the infection. However, surgical avulsion is another matter altogether. The first problem with avulsion is one of possible re-infection as the nail returns.
The second problem that can arise is that the distal dorsal tuft of the distal phalanx can hypertrophy, preventing the nail from completing its full excursion past the hyponychium. This will lead to a dorsal deformity of the distal toe. Eventually this can lead to distally infected ingrown nails requiring matrixectomy for resolution of the problem.
A Guide To Current And Emerging Topical Treatments
In the early 1990s, the Food and Drug Administration (FDA) stated that no topical remedy could claim efficacy against onychomycosis. Currently, only ciclopirox lacquer (Penlac, Sanofi Aventis) is approved for mild to moderate onychomycosis of the fingers or toenails.