Keys To Managing Severe Onychomycosis

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Author(s): 
Myron Bodman, DPM

   Gupta reports one can use terbinafine safely in children and the elderly.23 However, clinicians should always exercise caution in patients with major polypharmacy. It may be best to use alternate therapy in these cases to avoid adverse drug reactions in patients with an essentially benign disease.

A Closer Look At Topical Therapy Agents

Oral therapy is the most effective therapy for severe onychomycosis but for some patients, it is medically inappropriate. Additionally, for many patients, there is a strong personal preference for a non-systemic approach.24 Topical therapy would seem to be a good solution to the problem if only the efficacy rates were better. Many OTC and prescription products are available, hinting that there is no clearly effective topical choice. So what does the best evidence tell us?

   Ciclopirox 8% lacquer (Loprox, Medicis) is the best topical available in the U.S. for onychomycosis.25 Despite this, it achieves less than a 9 percent complete clearing rate and is only indicated for cases of mild to moderate severity without lunula involvement. This certainly leaves out severe, thick onychomycosis.25 In a yearlong study, the complete cure rate for terbinafine solution was no better than vehicle and nail thickness naturally impeded any improvement.26

   Since the market for an effective topical therapy for onychomycosis is large, researchers are currently studying many drugs and modalities. The most notable new topical drugs are tavaborole (AN2690, Anacor Pharmaceuticals), which belongs to the benzoxaborole class of drugs, and efinaconazole (Valeant Pharmaceuticals) and luliconazole (Topica Pharmaceuticals), which belong to the azole class of drugs.27

   In topical drug delivery, the vehicle seems to make the difference. The active ingredient in ciclopirox lacquer goes to the site of the infection in the nail bed by using an occlusive surface sealant of hair spray (Gantrez). It seals the nail plate, slowing the evaporation of water and establishing a diffusion gradient to facilitate the passage of ciclopirox through the hydrophilic nail plate to the nail bed.

   Many available topical therapies contain agents that are fungistatic in vitro but offer no evidence demonstrating penetration to the site of the infection in the nail bed. Companies often market topicals with anecdotal reports of effectiveness and illustrated with before and after images, but these agents lack controlled efficacy studies. Typically, topicals contain a tried and true antifungal agent dissolved in alcohol or vegetable oil vehicles to attempt nail plate penetration. Some commonly recommended topical antifungal solutions even lack an indication for onychomycosis but nonetheless come with a convenient brush applicator for nails.28,29

Assessing The Role Of Debridement In Managing Symptoms Of Severe Onychomycosis

To control symptoms and reduce the risks of subungual ulceration and secondary bacterial infection, clinicians can use periodic debridement to successfully manage severe onychomycosis in patients who are unable to benefit from oral therapy or unable to apply topicals. Unfortunately, debridement is unlikely to clear fungal infections.30

   Debridement techniques may vary but the goals of symptom control and risk reduction are the same. One successful method is to prepare the nail with a softening agent like diluted antimicrobial soap solution or a wetting agent. One can reduce the bulk of the nail plate with a large nail nipper and subsequently thin and smooth the nail plate with a 25,000 rpm rotary instrument. Use a coarse, fluted, pear-shaped rotary burr with firm, proximal to distal longitudinal and transverse strokes. A continuous spray of alcohol solution cools the digit and sequesters the fine nail debris. Pressure, pain and discomfort often immediately resolve.

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