Novel Pediculicide Clears Most Head Lice With 1 Application

Caroline Helwick

October 22, 2012

NEW ORLEANS — An experimental pediculicide lotion that relies on a totally new mechanism of action successfully eradicates head lice, according to a new study.

The results were presented by Vernon M. Bowles, PhD, from the University of Melbourne in Australia, here at the American Academy of Pediatrics 2012 National Conference and Exhibition.

"Our novel topical head lice product resulted in an 86% treatment success rate using the FDA-accepted end point of lice clearance at day 14, and in the absence of nit combing," Dr. Bowles said. "Only a single 10-minute application was required for efficacy, providing clinical evidence for both ovicidal and lousicidal activity."

The compound belongs to the class of chemicals known as bipyridyls.

Although there are many products on the market, head lice remains a persistent problem. The reasons for this include ineffective products, poor compliance, and lice that have become resistant to current products, Dr. Bowles explained.

"The need to laboriously comb the hair after treatment to remove still-viable eggs unaffected by the treatment adds to poor compliance and treatment failures," he noted. "We need new and improved treatments."

The phase 2b multicenter, randomized, double-blind, vehicle-controlled, parallel-treatment study compared low-dose (0.37% weight/volume) and high-dose (0.74% weight/volume) formulations of the pediculicide with a control vehicle in 142 male and female subjects 2 years and older. All subjects were white, and the majority were Hispanic and female. All infested household members were assigned to the same treatment group.

The experimental pediculicide was applied to the scalp and hair until saturated, left for 10 minutes, and then rinsed with water. Subjects were not instructed to comb nits.

All subjects returned to the study site for at least 3 follow-up visits (to day 14).

Treatment success — defined as being lice-free on all 3 visits — was observed in 23% of the placebo group, 67% of the low-dose group, and 86% of the high-dose group (P < .001), Dr. Bowles reported.

In the primary efficacy analysis, missing values were considered to be treatment failures, he added.

Adverse events, which were mostly mild, were reported by 27% of the high-dose group, 46% of the low-dose group and, interestingly, 57% of the placebo group.

The most common treatment-related adverse event was pruritus, reported by 4%, 17%, and 38%, respectively.

A few subjects had erythema and self-limited rashes. There were no serious adverse events or withdrawals related to the product, and no clinically significant changes in laboratory parameters, he said.

Novel Mechanism of Action

Other head lice treatments are often less effective against the eggs; hence, repeat applications are needed to eliminate an infestation, Dr. Bowles explained. In addition, although head lice have developed resistance to many of the available products, this pediculicide has no known cross resistance.

The compound targets metal-dependent proteins in the lice and their eggs and inhibits metalloproteases known to impede all stages of the louse lifecycle, he said.

The high-dose formulation was identified as the dose for pivotal registration studies. Two large phase 3 studies are planned.

Jeffrey K. Okamoto, MD, assistant professor of pediatrics at the University of Hawaii at Manoa, commented on the need for another agent to treat head lice.

"Some of our current pediculicides are losing efficacy because, like antibiotics, resistance to the product builds up and we have to move on to the next one," he said. "We need something that works differently, and I am happy to hear that one is in development."

Dr. Bowles reports founding and owning stock in Hatchtech Pty Ltd. Dr. Okamoto has disclosed no relevant financial relationships.

American Academy of Pediatrics (AAP) 2012 National Conference and Exhibition: Abstract 16372. Presented October 20, 2012.

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