WASHINGTON — A novel topical antiviral nanoemulsion reduced the time to healing of cold sores by more than 1 day in a phase IIB study of patients with recurrent herpes labialis.
The lotion, called NB-001, is an oil-in-water emulsion containing nanometer-size droplets that permeate the skin and fuse with the herpes virus, thereby disrupting its outer surface and lysing it, without irritating normal skin. The physical mechanism of action makes drug resistance unlikely, Dr. Mary R. Flack said at the jointly held annual Interscience Conference on Antimicrobial Agents and Chemotherapy and the annual meeting of the Infectious Diseases Society of America.
The 1-day benefit seen with NB-001 is similar to that seen with oral antiviral drugs such as famciclovir and valacyclovir, available only by prescription because the Food and Drug Administration is concerned about drug resistance. Prescription and over-the-counter topical antivirals, such as docosanol, acyclovir, and penciclovir, speed healing by about half a day.
“We need a topical product that is as effective as the orals. Nanoemulsion could provide such a product,” said Dr. Flack, vice president of clinical affairs at NanoBio Corp., Ann Arbor, Mich.
In a 28-center, double-blind, vehicle-controlled trial conducted by the company, 991 patients with a history of at least three cold sores per year were randomized to receive either vehicle alone or NB-001 in concentrations of 0.1%, 0.3%, or 0.5%. At symptom onset, patients began treatment five times daily until the lesion healed, or a maximum of 4 days. Of 484 patients who had an outbreak during the 6-month study, 482 received at least one dose of study medication. Of those, 92% started treatment within 4 hours of symptom onset at the prodrome or erythema stage.
The 482 patients in the intent-to-treat population had a mean age of 44 years, 71% were women, and 94% were white. Both median and mean times to healing for the group that received 0.3% NB-001 were a day or more improved, vs. vehicle alone. The group receiving 0.1% NB-001 healed about half a day faster, which was not statistically significant but was similar to the benefit seen with current topical antivirals.
The 0.5% concentration, in contrast, did not significantly reduce time to healing. At concentrations greater than 0.3%, there was precipitation of one ingredient that formed crystals, preventing permeation of the drug. This is a common phenomenon with topical agents, Dr. Flack said.
None of the subjects had drug-related skin irritation. Only negligible levels of plasma cetylpyridinium chloride (a marker for nanodroplet delivery) were seen in both treated and vehicle subjects, indicating no systemic exposure, she said.
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