I read with interest the article by Franz et al1 in a recent issue of the Archives concerning a comparative study of percutaneous absorption of lindane and permethrin and the extensive review of permethrin pharmacology in the editorial by Meinking and Taplin.2
Both the study and the editorial failed to mention that although permethrin does not cross the cutaneous barrier in normal adult skin, the situation may be different in children and patients with eczematous skin, badly excoriated skin, and heavily infested skin. In scabies infestation, the mite burrows to and probably through the stratum corneum to saturate the burrow with lymph, and so procure nutrients and water.3 Access to the dermis and then the systemic circulation for any topical insecticide is thus guaranteed. Repeating the study in animal or human models in these situations should be undertaken, as they may produce different results.
The study seems
Downs A. Comparing Antiscabies Treatments. Arch Dermatol. 1997;133(4):526. doi:10.1001/archderm.1997.03890400132020