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Topical Ivermectin Lotion for the Treatment of Head Lice

One 10-minute application was very effective and could help avoid systemic medication.

Although head lice do not transmit disease, infestation causes pruritus, eczematization, social stigmatization, and school absence. Use of the first- line agents permethrin and pyrethrins is limited by emerging resistance. Lindane is disfavored because of neurologic toxicity, and malathion is flammable. Two recently approved agents, spinosad and benzyl alcohol lotion, are relatively expensive. Oral ivermectin has known efficacy when other treatments have failed. These researchers report the findings of two manufacturer-supported studies of topical ivermectin.

In multicenter, randomized, double-blinded, vehicle-controlled trials of a single dose of ivermectin 0.5% lotion without nit combing, a total of 132 index patients aged 6 months and older with three or more live lice (and more than 600 family members who had 1 or more live lice) received ivermectin lotion or vehicle alone. The primary end point was the number of patients who were louse-free by day 2 and remained louse-free through days 8 and 15. Ivermectin or vehicle was applied to dry hair and rinsed out after 10 minutes. In the intention-to-treat population, significantly more ivermectin recipients than vehicle recipients were louse-free on day 2 (95% vs. 31%), day 8 (85% vs. 21%), and day 15 (74% vs. 18%; P<0.001 for each comparison). Adverse events, including pruritus, excoriation, and erythema, occurred equally often with ivermectin and control (in approximately 1% of both groups).

Comment: Results of this large, rigorous study indicate that single-dose topical ivermectin 0.5% lotion without nit combing is well-tolerated and very effective. The day 15 louse-free rate of 74% resembles rates with other two-application topical agents and may reflect imperfect application, viable eggs, or reinfestation. A second application may improve prolonged clearance rates. Head-to-head studies, resistance data, postmarketing data, and cost-benefit analysis are needed to determine which topical agents should be first-line therapy, which should be reserved for certain populations, and when oral pediculicides are appropriate. Lastly, changes in no-nit policies are needed to prevent unnecessary school absenteeism.

— Mary Wu Chang, MD

Published in Journal Watch Dermatology October 31, 2012

Citation(s):

Pariser DM et al. Topical 0.5% ivermectin lotion for treatment of head lice. N Engl J Med 2012 Nov 1; 367:1687. (http://dx.doi.org/10.1056/NEJMoa1200107)

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Reader Remarks:

Review and add to remarks on this article

• Control
  John T Boyd, MAMC Ft. Lewis, 2 Nov 2012 2:37 PM EST
  Specialty: Pediatrics
  Why was nix or some other agent not used ? Is the new tx any better than current , no... [more]
• oral vs topica
  Sandeep Saluja, 5 Nov 2012 1:13 PM EST
  Specialty: Internal Medicine
  How would oral preparation compare with topical one?

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