Abstract
BackgroundThe eggs of head lice are fixed to the hair of their hosts by means of a persistent glue-like fixative that is not chemically bound to the substrate. Eggshells stuck to hairs after successfully treating the infestation are a cosmetic issue and a source of misunderstanding about whether the infestation is eliminated. Hitherto, no effective treatment to loosen louse eggs and nits has been found.MethodsAn extensive screening of surface active compounds, oils, esters, and other cosmetic lubricants used a slip-peel device to measure the forces required to release the grip of the fixative. Promisingly effective compounds were formulated into suitable carriers for further testing. The most effective combination formulation was tested, as a commercial product (Hedrin Stubborn Egg Loosening Lotion), in a usage study of 15 children with nits, in which one half of the head was combed only on damp hair and the other half combed after a 10 min treatment using the product.ResultsLaboratory tests of the forces required to remove nits found that pelagonic acid derivatives, particularly isononyl isononanoate, in the presence of a polymeric gelling agent and water, were most effective to reduce the initial grip of the fixative as well as reducing friction as the eggshell is drawn along the hair shaft and that the final product was significantly (p < 0.05) more effective than several other marketed materials. In the usage study significantly (p = 0.01046) more louse eggs and nits were removed after treatment with the gel.DiscussionThe product developed through this study is the first with a demonstrable efficacy for loosening the grip of the louse egg fixative from hair. Consequently, until now, and despite the availability of effective pediculicidal treatments, dealing with the eggshells persisting after an infestation has been an onerous task for most households. This type of product can enable families to deal more easily with persistent eggshells and improve self-esteem in affected children.
Highlights
Insects of the order Phthiraptera all lay eggs that are fixed either to the hairs or the feather barbs of their hosts by means of a glue-like substance that is deposited and sets extremelyHow to cite this article Brunton ER, Whelan IP, French R, Burgess MN, Burgess IF. 2019
We found incorporation of isononyl isononanoate (ININ) into other oily materials considered to have lubricant properties; such as polyethylene glycol (PEG) dimeticones, the head louse treatment 4.0% dimeticone gel, which contains a PEGylated dimeticone, or siloxane alternatives such as polyisobutene compounds; reduced the activity of the ININ even on dry hair
The only significant difference in terms of Peak force across this group of mixtures was between ININ on its own, applied to dry hair, and ININ mixed into 4% dimeticone gel (p = 0.035624)
Summary
Insects of the order Phthiraptera all lay eggs that are fixed either to the hairs or the feather barbs of their hosts by means of a glue-like substance that is deposited and sets extremelyHow to cite this article Brunton ER, Whelan IP, French R, Burgess MN, Burgess IF. 2019. The most effective combination formulation was tested, as a commercial product (Hedrin Stubborn Egg Loosening Lotion), in a usage study of 15 children with nits, in which one half of the head was combed only on damp hair and the other half combed after a 10 min treatment using the product. Laboratory tests of the forces required to remove nits found that pelagonic acid derivatives, isononyl isononanoate, in the presence of a polymeric gelling agent and water, were most effective to reduce the initial grip of the fixative as well as reducing friction as the eggshell is drawn along the hair shaft and that the final product was significantly (p < 0.05) more effective than several other marketed materials. This type of product can enable families to deal more with persistent eggshells and improve self-esteem in affected children
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