Laird Harrison

November 02, 2016

SAN FRANCISCO — The experimental compound abametapir kills lice and their eggs, according to new research.

Abametapir could take the place of standard treatments such as permethrin, which are losing their efficacy, so this is "exciting," said Vernon Bowles, PhD, from the University of Melbourne in Australia, who is the inventor of the treatment and a founder of HatchTech, the company developing the compound.

And it offers the advantage of requiring only one application, he told Medscape Medical News.

Dr Bowles presented the finding here at the American Academy of Pediatrics 2016 National Conference and Exhibition.

Treatments for head lice currently on the market kill hatched lice but are not very effective against their eggs, he explained. Patients need to undergo a second treatment 7 to 10 days after the first to kill the next generation of lice.

In contrast, abametapir works by inhibiting metalloproteinases, the enzymes needed for both egg development and the survival of hatched lice.

Dr Bowles has spent much of his career studying these compounds. He began working on abametapir in 2001 and eventually formulated a lotion with a 0.74% concentration. "It's been a long haul," he said.

He is working with Promius Pharma and has applied for approval from the US Food and Drug Administration to market the treatment as a prescription in the United States.

Dr Bowles and his colleagues conducted two randomized, double-blind, vehicle-controlled, parallel-group phase 3 clinical trials of the compound. The team recruited 704 people with lice. All participants were at least 6 months old, and about one third were children.

Households with study participants were randomly assigned to treatment with abametapir or placebo, which was the vehicle lotion with no active ingredient.

The lotion is applied to dry hair, left for 10 minutes, and then rinsed with warm water. There was no nit combing. In the two trials, the treatment was significantly more likely to kill all the lice and eggs than the placebo.

Table 1. Patients Cleared of Lice at Day 14

Study Abametapir Group (n = 187) (%) Placebo Group (n = 192) (%) P Value
Study 1 88.2 62.0 <.001
Study 2 81.0 60.5 <.001

 

Treatment-emergent adverse events in the two trials were more common in the abametapir group than in the placebo group (4.0% vs 1.7%).

The most common adverse event was rash, followed by a burning skin sensation, contact dermatitis, vomiting, eye irritation, and hair color changes.

Hatch Rates

In another double-blind trial, 50 people 3 to 17 years of age were randomly assigned to 0.74% abametapir lotion or to placebo lotion.

Dr Bowles and his team removed at least five louse eggs from each head before and after treatment.

All eggs were incubated at 30°C and 60% relative humidity for 14 days. The hatch rate was significantly lower after treatment with abametapir than after treatment with placebo (P < .0001).

Table 2. Hatch Rate of Eggs Incubated for 14 Days

Time of Egg Retrieval Abametapir Group (n = 25) (%) Placebo Group (n = 25) (%)
Before treatment 93.3 79.5
After treatment 0.0 36.0

 

After the presentation, a member of the audience asked why the placebo lotion was surprisingly effective.

"The vehicle mineral oil is a suffocant," Dr Bowles explained. However, clearing lice in only 60% of patients is "not commercially viable," he noted.

Another audience member asked about cost and reported that treatments for lice in the Philippines sell for about $2.

"This product has been developed primarily for the US market, so it's not going to be a $2 product," Dr Bowles pointed out. However, "it may over time become an over-the-counter product."

Another person wanted to know whether abametapir is absorbed through the skin.

It is, but "we have seen no safety signals at all," Dr Bowles replied.

"It offers a complete solution to a problem that has vexed pediatricians for the ages," said Mitchell Goldstein, MD, from the Loma Linda University School of Medicine in California.

It will be important to compare the adverse events with abametapir with those of other treatments for lice, he told Medscape Medical News.

This study was funded by HatchTech, which is developing the abametapir lotion. Dr Bowles is a founder of Hatchtech. Dr Goldstein has disclosed no relevant financial relationships.

American Academy of Pediatrics (AAP) 2016 National Conference and Exhibition: Abstracts 319920 and 329922. Presented October 24, 2016.

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