Efficacy of chemical and botanical over-the-counter pediculicides available in Brazil, and off-label treatments, against head lice ex vivo.
BACKGROUND
There is a lack of reliable data on the efficacy of over-the-counter (OTC) pediculicides in Brazil.


METHODS
We performed ex vivo assays of eight marketed pediculicides: 1% permethrin (Kwell, Clean Hair, Keltrina, Nedax), 0.02% deltamethrin (Deltacid, Pediderm), and two "natural" products (Piolho e Lêndea, Pilogenio). We also tested 5% permethrin (Keltrina Plus), traditional home remedies and an ivermectin-based product used in veterinary medicine. Head lice (49-52 per group) were immersed in the compound for 3 min and washed after 20 min to simulate the typical in vivo treatment protocol. Lice were examined for activity up to 24 h using stringent criteria for survival.


RESULTS
Of the permethrin containing products, highest mortality was observed with Kwell and Clean Hair (97.9 and 90.2% after 4 h). Keltrina, Nedax, Keltrina Plus, and the two deltamethrin-based products showed only a low efficacy of <60% after 4 h. With exception of pure coconut oil (80% mortality after 4 h), home remedies showed a very low efficacy, and both marketed products killed few lice. The ivermectin-based product caused a mortality of 100% after 4 h.


CONCLUSIONS
Most Brazilian OTC products did not show a satisfactory efficacy against head lice. Resistance may be present. Ivermectin and coconut oil are promising compounds for topical treatment. Laboratory-based tests should be used to assess resistance patterns and to identify formulations of the active ingredient that increase the efficacy. Standardized testing should be performed before a product is licensed for head lice treatment.
Asenov
André
A
Department of Hygiene and Microbiology, Charité Medical School, Campus Benjamin Franklin, Berlin, Germany.
Oliveira
Fabíola Araújo
FA
Speare
Rick
R
Liesenfeld
Oliver
O
Hengge
Ulrich R
UR
Heukelbach
Jorg
J
D000818:Animals; D001938:Brazil; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D004366:Nonprescription Drugs / Q000494:pharmacology*; D010374:Pediculus / Q000187:drug effects*; D028321:Plant Preparations / Q000494:pharmacology*
D007306:Insecticides; D004366:Nonprescription Drugs; D028321:Plant Preparations