In 2014, two new topical solutions for onychomycosis were FDA approved: efinaconazole (Jublia, Valeant Pharmaceuticals) and tavaborole (Kerydin, PharmaDerm). The complete cure rates of tavaborole 5 % solution are 6.5–9.1 %, and the complete cure rates for efinaconazole 10 % solution are 15.2–17.8 % [14–16]. Both efinaconazole and tavaborole were studied in Phase 3 clinical trials where their protocols were not identical. In both studies, patients applied the topical antifungal or vehicle once daily for 48 weeks with a four-week follow-up; however, they vary in their percent nail involvement, age limit, and other criteria. Therefore, it is impossible to make a head-to-head comparison between both medications.

Elewski et al. assessed the efficacy, safety, and tolerability of efinaconazole in two double-blind, randomized, vehicle-controlled, multicenter studies in 1655 patients with mild to moderate onychomycosis (ranging between 20 and 50 % affected target toenail involvement) [16]. In addition to the aforementioned complete cure rates, researchers noted significantly greater mycologic cure rates (55.2 and 53.4 %) in efinaconazole-treated patients in comparison to the vehicle control.

Elewski and colleagues also studied tavaborole in two parallel designed studies of 1197 patients with mild to moderate onychomycosis (ranging between 20 and 60 % affected target toenail involvement) with slight differences in enrollment criteria [14, 15]. In the two studies, 26.1 and 27.5 percent of patients treated with tavaborole achieved a completely or almost clear nail at 52 weeks in comparison to 9.3 and 14.6 % in the vehicle groups. The study authors also noted that the rates of negative mycology in the tavaborole groups were 31.1 and 35.9 % in comparison to 7.2 and 12.2 % in the vehicle groups.

Lacquer-based topical therapies are applied primarily to the exterior nail plate, with drug reaching the infection site mostly through nail permeation [4, 5, 17]. Much has been written about topical onychomycosis treatments and the challenge of effective nail penetration following their application to the nail plate with the dorsal layer acting as the major barrier to penetration [18, 19]. Researchers have emphasized the need for the active ingredient to pass through the nail plate to reach the site of infection and have suggested a number of physicochemical factors (such as molecular size, hydrophilic or lipophilic nature of the agent, pH, ionic strength, and nature of the vehicle formulation) as important factors in influencing permeability [18]. Studies have reported variable nail permeability for all the available topical preparations available in the United States and work continues to find agents and formulation approaches to enhance nail penetration [20–23].

Efinaconazole is an alcohol-based solution that provides low surface tension and good wetting properties [24]. In a study of 11 patients with onychomycosis, Elewski et al. found that applying efinaconazole vehicle solution solely to the hyponychium spreads the topical into the subungual space between the nail plate and nail bed, reaching the site of infection [25]. Application to the hyponychium and ventral aspect of the nail plate may be important in patients wishing to continue to use nail polish [26]. Although nail polish does not appear to influence efinaconazole penetration into the nail, nail polish can become tacky with repeated application [27].

Tavaborole is also an alcohol-based solution that provides low surface tension but also boasts a low molecular weight-active ingredient that penetrates well through the human nail plate [16]. In a human cadaver nail study, tavaborole penetrated the nail plate 40 times greater than topical ciclopirox [28]. Up to four layers of nail polish does not seem to inhibit penetration of tavaborole [29]. In neither efinaconazole nor tavaborole has the impact of nail polish on efficacy been assessed, nor is it contraindicated.

As toenail growth progresses from proximal to distal, newly formed nail plate replaces diseased nail, a process that can take 12–18 months [29]. Clinical trial data suggest tavaborole and efinaconazole should be applied daily to the toenails for at least 48 weeks. Some patients may require treatment for considerably longer because of slow toenail growth, disease severity, or for other reasons. It is not known whether longer treatment regimens with tavaborole or efinaconazole would produce better efficacy results; however, higher cure rates following longer follow-up periods have been reported with other agents [30–32].

It is important that patients recognize that “cure” may not translate to a completely clear nail [33]. Poor adherence with any long-term chronic therapy is well documented [34]. A number of post hoc analyses with efinaconazole have been carried out to better identify prognostic factors for treatment success. Gender [35] and disease severity [36] were significant influencers of complete cure over the duration of the studies; female patients and those with milder disease may see results much quicker in clinical practice, whereas male patients and those with moderately severe disease may require a longer treatment course or combination therapy with oral antifungals. Although male patients are more difficult to treat, reasons are unclear. They tend to seek help for more advanced disease and suffer more nail trauma; toenails tend to be thicker. The reduced rate of growth and thickness of the nail may be factors in more severe disease, although it may be that these patients just require longer treatment courses.

Tinea pedis is an important causative factor for onychomycosis, and better results are seen when any coexisting tinea pedis is also treated [37]. In addition, managing tinea pedis is critical to minimizing disease recurrence.

During and after treatment of the underlying infection seen in onychomycosis, the nail plate may not regain its original healthy appearance. Clinicians should consider other therapies and devices to use in combination with an antifungal therapy and/or use post topical antifungal therapy that will adhere to the nail plate, provide mechanical support, and be easy to use.

There are two medical devices available for the treatment of onychodystrophy: Genadur™ (hydroxypropyl chitosan, Medimetriks) and Nuvail™ (poly-ureaurethane, 16 %, Cipher). These are nondrug lacquers applied topically to the nail at bedtime. Genadur is indicated to “protect damaged nails from the effects of moisture, friction, or shear” in order to relieve the symptoms of nail dystrophy [38]. It is a hydrosoluble compound that should be applied after nail washing and drying. Studies on psoriatic nails have shown that it has an improvement in nail fragility, a reduction in splitting, and a 63 % reduction in onycholysis [39].

Nuvail is a waterproof and flexible film that forms to the nail contour to provide protection from direct abrasion and provides optimal moisture balance to protect the nail from the effects of moisture [40]. Nasir et al. followed 53 patients with nail dystrophy who used Nuvail nightly [41]. Clinical assessment, which evaluated color, onycholysis, and subungual hyperkeratosis, resulted in a 60 % improvement after 6 months of use.

In addition, if cosmesis is a concern for the patient, Keryflex™ nail resin may be applied to camouflage and protect the nail unit. A podiatric office-based therapy, Keryflex™ (Podiatree Company), has been used to cover nail fungus and various other nail dystrophies whether the patient is being systemically treated for the underlying condition or not. Among its many uses, it has been applied following the use of the laser for onychomycosis and in covering a nail that has become dystrophic following surgery for paronychia. It is a flexible nail resin that is not suitable for fingernails, as it moves with the foot and takes some impact of external forces, making it suitable for use in athletes and dancers who regularly traumatize the toenails.