Ivermectin cream demonstrates activity against head lice eggs

In a study sponsored by Topaz Pharmaceuticals Inc., a privately held specialty pharmaceutical company, scientists from the University of Massachusetts, Amherst presented data showing that a 0.5% ivermectin (IVM) cream formulation was active against lice eggs from permethrin resistant head lice.  The data were presented in a poster presentation on Saturday, July 9, 2011 at the 37th Annual Meeting of the Society for Pediatric Dermatology in Baltimore, Maryland.  

"These data build on our earlier work showing this ivermectin formulation is active against head lice," said John M. Clark, Ph.D., Professor of Veterinary and Animal Sciences, University of Massachusetts Amherst.  "The data suggest that a single treatment with 0.5% ivermectin cream has the potential to fully break the head louse life cycle.   If approved by the FDA, ivermectin cream has the potential to provide physicians with an attractive treatment option."  

In the study, permethrin resistant head lice were allowed to lay eggs in tufts of human hair.  Adult lice were removed and the tufts with eggs were exposed to 0.5% ivermectin cream, to vehicle only, or to unformulated, diluted ivermectin. After a 10-minute exposure, tufts were thoroughly rinsed and incubated.  Any hatched lice were placed onto new tufts and moved to a feeding cup.  The hatchability of treated eggs was not affected by ivermectin. No differences were detected between the mortality rate of eggs exposed to 0.5% ivermectin cream and those exposed to unformulated ivermectin.  The percent of hatched lice from eggs exposed to 0.5% ivermectin cream that took a blood meal, relative to eggs exposed to placebo, was significantly decreased (by 82-95%).  All hatched lice from eggs treated with 0.5% ivermectin cream died within 48 hours.