A new two-phase dimeticone pediculicide shows high efficacy in a comparative bioassay.
BACKGROUND
Dimeticones kill head lice by physical means. Here we assessed in a comparative bioassay the ex vivo efficacy of "NYDA sensitiv", a new two-phase dimeticone-based pediculicide similar to a product established on the market, but without fragrances.


METHODS
We compared efficacy of the new product to a positive dimeticone control group, a sample of four other insecticidal and natural head lice products marketed in Germany, and an untreated control. In a bioassay, lice were exposed ex vivo to products and examined for activity for up to 24 hours, following a standard protocol.


RESULTS
After 6 and 24 hours, 13.7 and 88.5% of untreated control lice did not show major vital signs. In contrast, no lice showed major vital signs 5 minutes after treatment with the new product or the control dimeticone group (NYDA). This effect persisted at all observation points (100% efficacy). Efficacy of 0.5% permethrin (Infectopedicul) ranged between 76 and 96% in evaluations between 5 min and 6 hours. All lice treated with a coconut-based compound (mosquito Läuseshampoo) did not show major vital signs after 5 min, but mortality was only 58% after one hour. Pyrethrum extract (Goldgeist forte) showed an efficacy of 22 - 52% between 5 min and 3 hours after treatment; after 6 hours, 76% of lice were judged dead. An oxyphthirine-based compound (Liberalice DUO LP-PRO) killed 22 - 54% of lice in the first 6 hours.


CONCLUSIONS
The two-phase dimeticone compound NYDA sensitiv is highly efficacious. The removal of fragrances as compared to an established dimeticone product did not affect in vitro efficacy.
Heukelbach
Jorg
J
Department of Community Health, Federal University of Ceará, Costa Mendes, Fortaleza CE, Brazil. heukelbach@web.de
Asenov
André
A
Liesenfeld
Oliver
O
Mirmohammadsadegh
Ali
A
Oliveira
Fabíola A
FA
D000818:Animals; D001681:Biological Assay; D002648:Child; D004129:Dimethylpolysiloxanes / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D010373:Lice Infestations / Q000188:drug therapy; D010374:Pediculus / Q000187:drug effects*; D012536:Scalp Dermatoses / Q000188:drug therapy
D004129:Dimethylpolysiloxanes; C501844:dimethicone