MONTREAL — A product that dehydrates, rather than poisons, head lice should be available soon in the United States to fill a gap widened by parental concerns about the toxicity of existing treatments, Dr. Ian Landells, said at Dermatology Update 2007.
The treatment, which was launched in Britain 2 years ago as Full Marks solution (SSL International) and in Canada last fall as Resultz (Altana Pharma Inc.), contains 50% isopropyl myristate as its active ingredient and works by dissolving the waxy exoskeleton of lice and causing dehydration.
“This is the first clinically proven toxin-free treatment that has a mechanical mode of action,” said Dr. Landells of Memorial University, St. John's, Nfld. “It's a really nice alternative and the only treatment I am going to be recommending from now on.”
The product is currently in phase III trials in the United States and is expected to be marketed here by Piedmont Pharma in the next few years, noted Dr. Landells, who has served on the advisory board for Altana.
An increasing number of parents are expressing reluctance about using currently available pediculocides on their children because of concerns about neurotoxicity and lack of efficacy.
Company data on a Canadian efficacy and safety trial showed that treatment with Resultz eliminated 100% of live lice at 24 hours, resulting in an overall 96.5% cure rate. A second treatment 1 week after the first is very important to catch any new lice that may have hatched from remaining nits, Dr. Landells said.
In addition, he presented data from a company-sponsored phase II trial comparing Resultz with a pyrethrin plus piperonyl butoxide product (Rid) and a phase III trial comparing it with a permethrin 1% product (Nix/Lyclear). The cure rates in the first study, which involved 52 patients, were 63% for Resultz and 23% for Rid. In the second study (94 patients), the cure rates were 78% for Resultz and 20% for Nix/Lyclear, he said.
Adverse events for Resultz were mild and less frequent than for permethrin 1% (11% vs. 29%). They included rash, tingling, burning and dry scalp, and stinging eyes, and resolved within 24 hours. “It's a harmless surfactant found in products like soaps that we use on kids all the time,” he concluded, noting that because it is toxin free, there are no safety concerns about repeated treatments.
Isopropyl myristate is used to dissolve the waxy exoskeletons of head lice, causing them to die of dehydration. CDC/Dr. Dennis D. Juranek
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