As I discussed in my eZine entitled “Onychomycosis: What Is It and How is it Diagnosed”, you should have no doubt about it - this is an infection and as such, should be treated with an anti-infective. Unfortunately, for too many of our colleagues, onychomycosis is just a condition to be seen in the office for a mechanical debridement as quickly as possible and as frequently as an insurance carrier permits. This debridement, although useful for reducing the thickness of the nail, making it less painful and improving the overall appearance, does nothing to actually treat the infection. For that, you need an antifungal agent.

It is generally accepted that the oral antifungal agents are the most effective treatments. Currently, there are three FDA-approved drugs for the treatment of onychomycosis. Griseofulvin is mostly of historic interest only, as it was not particularly efficacious, had to be taken for prolonged periods of time and had some bothersome adverse events. Itraconazole was the first of the “newer” generation drugs to be approved, followed about one year later by terbinafine. These drugs both represented a major advance over griseofulvin in that they could be given for shorter periods of time and are generally considered safer and more efficacious. With increasing evidence of lesser efficacy, a greater risk of drug-drug interactions and even a “black box” warning from the FDA, itraconazole, although still a useful and efficacious drug, eventually lost significant market share to terbinafine. With terbinafine now being available at many pharmacies for less than $20 for a three month course of therapy and its’ superior efficacy rates, it is somewhat surprising that the drug does not have more overall usage, especially for more severe cases of onychomycosis.

Certainly, there can be hepatic toxicity with this drug, but all of the studies have shown this to occur at an extremely low incidence. Likewise, although there is no interaction between terbinafine and statins, many physicians assume that there is because of this interaction being seen with azole antifungals. Even when a physician wants to prescribe one of these drugs, the patient often refuses them based on something they heard or read “on-line”.

Due to the reluctance to use oral antifungal agents, there has been tremendous interest in the development of a topical antifungal that would still be effective without any of the “baggage” that comes with the orals. The first FDA approved oral agent was ciclopirox 8% lacquer, first approved in late 1999. As expected, because of the tremendous backlash against the orals and the pent up demand, this drug had an incredible first year or two. However, perceived low efficacy and a lacquer formulation that was troublesome for patients and physicians alike soon took its toll on sales.

After an almost 15 year drought in new products, in the summer of 2014, two new topical agents were approved by the FDA; efinaconazole 10% solution and tavaborole 5% solution. Both of these drugs, being solutions and not lacquers, apply easily, the former with a brush and the later with a dropper, dry quickly and require no weekly removal. Furthermore, neither of the pivotal trials on which these drugs were FDA approved permitted debridement of the nail, although this certainly does not preclude the provider from performing the procedure. Theoretically, although never specifically studied, debridement may reduce the fungal load and thin the nail to permit even greater penetration of the drug to the site of the infection in the nail bed.

Efinaconazole, as with all azole antifungals, works by reducing ergosterol synthesis. Ergosterol is a necessary component of a healthy fungal cell wall. Tavaborole, an oxaborole, represents a new class of antifungal drug and works by inhibiting fungal protein synthesis.

Because both of these drugs are relatively new to the market, they are being promoted heavily. While there may be a tendency to want some sort of comparison of efficacy between the two, this is not currently possible, as they have never been studied in a head to head fashion. That would be the only “scientific” way to compare two drugs (I direct you to my eZine on onychomycosis clinical trial design). For now, it is up to the clinician to see what works best in their hands with their patient population.