Oral ivermectin was found superior to malathion lotion in eliminating persistent head lice infestation in a study of children and their household contacts, according to a report in the March 11 issue of the New England Journal of Medicine.
“Ivermectin may be a good alternative to malathion when topical insecticide resistance is suspected,” said Dr. Olivier Chosidow of the Université Pierre et Marie Curie, Paris, and his associates.
Resistance of head lice to both pyrethroids and malathion appears to be increasing. Ivermectin has been used to treat onchocerciasis, lymphatic filariasis, helminthiases, and ectoparasite infections such as scabies.
Dr. Chosidow and his colleagues assessed the efficacy and safety of ivermectin against head lice in a randomized, double-blind controlled trial of patients recruited from the community who had persistent infestation despite using topical pyrethroid-based or malathion insecticide.
The study involved 812 children and their contacts in 376 households in the United Kingdom, Ireland, France, and Israel. The study households were randomly assigned to receive either active oral ivermectin plus a placebo lotion (185 households and 398 patients) or active malathion lotion plus a placebo tablet (191 households and 414 patients) to ensure blinding to treatment assignment. The medications were given by trained staff at clinics to ensure that they were used properly.
After two treatments, given 1 week apart, any patients who still had head lice infestation were switched to the alternative treatment.
The primary end point – clearance of head lice infestation on day 15 after the first two treatments – was achieved in more than 95% of the ivermectin patients, compared with 85% of the malathion patients. A total of 92% of households in the ivermectin group were cleared of head lice, compared with 79% of households in the malathion group.
Seventy patients with persistent infestation switched to the alternative treatment. After another 2 weeks, 100% of the patients using malathion and 97% of those using ivermectin achieved clearance of head lice, the investigators said (N. Engl. J. Med. 2010;362:896-905).
Seven patients in the ivermectin group (1.8%) and five in the malathion group (1.2%) discontinued treatment because of adverse effects, including impetigo, nausea or vomiting, gastroenteritis, and rash or urticaria.
Two serious adverse events occurred: One girl taking ivermectin developed seizures 6 days after the first dose, and one girl taking malathion developed a severe headache requiring hospitalization 6 days after the first application. Both girls recovered. The seizure was found to have a right rolandic focus, and the patient was given a prescription for oxcarbazepine.
The study was funded by Johnson & Johnson–Merck Sharp & Dohme–Chibret. Dr. Chosidow reported receiving consulting fees from Laboratoires Pierre Fabre and Johnson & Johnson, and lecture fees from Pohl Boskamp.
(Image Copyright: CDC/Reed and Carnrick Pharmaceuticals)