Emerging Concepts In Treating Onychomycosis

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Author(s): 
John D. Mozena, DPM, and Joshua P. Mitnick, DPM

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.

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Eric Bornsteinsays: October 13, 2009 at 11:01 am

For professionals in the Podiatric community that are interested, here is the current Pivotal Study information on the Noveon from Nomir Medical Technologies

There were 36 subjects (53 Toes) enrolled in the study.

Starting after the completion of the second of the four treatments, all subjects were required to use a non-prescriptive topical agent: 1% topical terbinafine cream applied only between the toes to control or prevent tinea interdigitalis.

Patients were instructed to not get any cream on the nails.

Use of this topical between the toes only, was in accordance with the current listed product information and is neither FDA indicated, nor FDA cleared as a treatment for onychomycosis. Other adjunctive actions that are "standard of care", such as nail debridement or nail trimming, were allowed at each investigator’s discretion.

Control subjects were handled identically in all respects to those who were treated, except for, of course, with sham “treatment” there was no energy delivery. The highest treatment site temperature was 100.5°F.

All study subjects had to have laboratory confirmation of onychomycosis by either positive culture using a selective dermatophyte test medium, or positive periodic acid-Schiff staining (PAS) from a toenail sample.

The mycology was followed and data taken for the 180 day balance of the study.

The top-line preliminary 120-day data analysis that was presented at the Council for Nail Disorders 13th Annual Scientific Meeting, and demonstrated that after Noveon treatment, 76.3 percent of the treated toes showed evidence of clinical improvement (p<0.02), and a significant drop in positive culture was seen in 74 percent of the treated toes after only two treatments (before the introduction of the tinea pedis cream.)

This data was based on at least 120 days of follow-up on all enrolled patients. Additionally, no significant adverse events were reported.

The final 180 day data, is currently under review by the FDA in an application for 510(k) approval for Onychomycosis treatment, and has been accepted for publication with a Podiatric peer-review journal.

Completed pilot study data with this device can be found at:

Bornstein, E.S., A.H. Robbins, M. Michelon (2008) Photo-inactivation of fungal pathogens that cause onychomycosis in vitro and in vivo with the noveon dual wavelength laser system. 2008 New Cardiovascular Horizons Meeting Abstracts.

http://www.nomirmedical.com/pdf/NCH_...L_08-26-08.pdf

A lengthy discussion on this and other light-based onychomycosis technologies can be found at:

http://www.podiatry-arena.com/podiat...ad.php?t=22925

Eric Bornstein
Chief Science Officer
Nomir Medical Technologies

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