Comparative in vitro pediculicidal efficacy of treatments in a resistant head lice population in the United States.
OBJECTIVE
To compare the pediculicidal activity of 5 head lice products available in the United States on head lice from south Florida.


METHODS
In vitro pediculicidal product comparison.


METHODS
Lice Source Services, Inc, located in Plantation, Fla, a clinic for the treatment and grooming of individuals with pediculosis capitis.


METHODS
Head lice were collected from healthy clients with Pediculus capitis that came to Lice Source Services, Inc, to seek their services.


METHODS
Within 2 to 6 hours of capture, lice were placed in continuous direct contact with the pediculicide products and observed at regular intervals. Results were compared with findings of a recent study of a treatment-sensitive population of head lice conducted in Panama.


METHODS
Percentage of lice dead at regular observation intervals between 5 minutes and 3 hours of continuous exposure to the pediculicides.


RESULTS
Two prescription products, Ovide lotion (0.5% malathion) and 1% lindane shampoo, were ranked in the same order as in 2 previous studies (first and last, respectively). The order of effectiveness from most to least effective was as follows: Ovide lotion, A-200 shampoo (a natural pyrethrin product synergized with piperonyl butoxide), undiluted Nix (1% permethrin), diluted Nix, RID (a natural pyrethrin product synergized with piperonyl butoxide), and 1% lindane shampoo.


CONCLUSIONS
There were statistically significant differences in the efficacy of all the products when compared with the results found in the recent study in Panama, except for Ovide lotion. Of those tested, Ovide was the only pediculicide in the United States that had not become less effective. The difference in efficacy of 1% lindane, Nix, and pyrethrins between the Panama and Florida studies supports the argument that some head lice in the United States have become resistant to these treatments.
Meinking
Terri L
TL
Department of Dermatology and Cutaneous Surgery, University of Miami School of Medicine, PO Box 016960, R-117, Miami, FL 33101, USA. tmeinkin@med.miami.edu
Serrano
Lidia
L
Hard
Bruce
B
Entzel
Pamela
P
Lemard
Glendene
G
Rivera
Elisabeth
E
Villar
Maria Elena
ME
D000328:Adult; D000818:Animals; D002648:Child; D006203:Hair Preparations / Q000494:pharmacology*; D001556:Hexachlorocyclohexane / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007648:Kerosene; D010373:Lice Infestations / Q000188:drug therapy; D008294:Malathion / Q000494:pharmacology; D010374:Pediculus / Q000187:drug effects*; D010882:Piperonyl Butoxide / Q000494:pharmacology; D011722:Pyrethrins / Q000494:pharmacology; D012536:Scalp Dermatoses / Q000188:drug therapy
C050604:A 200 pyrinate shampoo; D006203:Hair Preparations; D007306:Insecticides; D007648:Kerosene; D011722:Pyrethrins; D001556:Hexachlorocyclohexane; D010882:Piperonyl Butoxide; D008294:Malathion