Topical Nanoemulsion Effective Against Chronic Toenail Fungal Infections

Deborah Brauser

March 17, 2010

March 17, 2010 (Miami Beach, Florida) — A new topical emulsion (currently known as NB-002; NanoBio Corporation) was effective in treating mild distal subungual onychomycosis (DSO), a chronic persistent toenail infection, within a month in the majority of patients, according to a post hoc analysis from a randomized study presented here at the American Academy of Dermatology 68th Annual Meeting.

"About 60% of the people in our active treatment groups had negative fungal cultures at the 4-week mark, which was a little surprising for a topical treatment," investigational team member Mary Flack, MD, vice president of clinical affairs at NanoBio in Ann Arbor, Michigan, told Medscape Dermatology. "Most topicals don't usually have that level of clearing."

One Third of Those Over 50 Affected

Onychomycosis is a disorder that affects 3% to 14% of adults, "leading to pain, disfigurement, and social embarrassment," reported Dr. Flack. She noted that it also affects up to a third of people older than 50 years.

"Although oral systemic antifungal agents are somewhat effective, they have a high relapse rate and safety risks that limit their use in older individuals and those with coexisting medical conditions," Dr. Flack said.

She noted that many people are reluctant "to take a pill for what is basically a cosmetic condition."

"NB-002, on the other hand, is a novel antifungal nanoemulsion composed of nanometer-sized droplets that mechanically destabilize fungal hyphae and spores," explained Dr. Flack.

For this study, Dr. Flack and her colleagues sought to evaluate the posttreatment mycologic cure (through a negative dermatophyte culture and potassium hydroxide microscopy) and effective treatment rates (calculated as mycologic cure plus 10% or less disease involvement or more than 5 mm of new nail growth) of NB-002 in DSO patients with 50% or less toenail involvement at baseline from an earlier phase 2A study.

"Even though [DSO] is a particular problem for older people, we wanted to include all comers, including young athletes in their 20s and 30s," noted Dr. Flack.

The investigators assessed data on 227 patients between 18 and 75 years of age (mean age, 51.8 years) with a mild (30% or less toenail involvement, n = 48) or moderate (31% to 51% involvement, n = 179) form of DSO.

These participants were randomized and received 42 weeks of treatment — placebo vehicle (once or twice a day) or the NB-002 emulsion 0.25% twice daily, 0.5% once daily, or 0.5% twice daily — applied to the adjacent skin of all 10 toenails. Effectiveness was then measured 4 and/or 8 weeks posttreatment.

Higher Cure Rates

Results at the end of the study showed that for the patients with mild DSO, all 3 emulsion groups had higher mycologic cure rates than the placebo groups. In addition, the difference between the 0.5% once daily group and the placebo group was statistically significant (57.1 vs 8.3%; P < .05).

In the patients with moderate DSO, the 3 emulsion groups also had higher mycologic cure rates, with a significant difference between the rate with 0.5% twice daily and placebo (45.3 vs 15.2%; P < .05).

The effective treatment rates in the 3 emulsion groups for patients with mild DSO ranged from 20% to 35.7%, compared with 8.3% in the placebo groups. For patients with moderate DSO, the rates for the 3 emulsion groups were lower, ranging from 5.6% (for the 0.25% twice daily group) to 17.8%, compared with 8.7% for the placebo groups.

"The topical administration of NB-002 did result in improved rates of mycological cure, regardless of baseline disease stage, although the rates of effective treatment and clear nail were higher in those with mild baseline disease," said Dr. Flack.

"The combination of topical administration, excellent safety profile, sporicidal activity, and lack of resistance potential represents a possible breakthrough in the treatment of mild onychomycosis, making it another option for patients — especially if they have mild disease and don't want to be exposed to the risks of an oral medication," she summarized.

Interesting But Inconclusive

"Although this was an interesting study, in my mind it was inconclusive," said Joel Schlessinger, MD, president of Advanced Skin Research in Omaha, Nebraska.

"The effective treatment rates were quite low [in the moderate group], and the [placebo] group showed superiority to 1 of the treatment groups. Even the 17.8% in the best treatment group, compared with 8.7% for the [placebo] is not enough to show superiority, in my opinion. It's important to see a significant difference between a placebo and a treatment."

Dr. Schlessinger was not involved with this trial but did present findings at the meeting from his own study on an oral antifungal treatment for onychomycosis.

"Many people do want a topical, and I think there's a great deal of interest in finding a topical that will actually work. So far that hasn't really panned out, but we'll continue to hope."

"I think the important takeaway message for clinicians is to realize there are new treatments in the works for onychomycosis, and other options should be available down the line," he concluded.

This study was supported by NanoBio, which employs Dr. Flack. Dr. Schlessinger did not disclose any relevant financial relationships.

American Academy of Dermatology (AAD) 68th Annual Meeting: Abstract P2108. Presented March 8, 2010.