A Topical Treatment for Resistant Head Lice
Pariser DM, Meinking TL, Bell M, Ryan WG
N Engl J Med. 2012;367:1687-1693
Head lice resistance to the 2 groups of medications that have long been first-line treatments -- permethrin and pyrethrins -- is increasing. Second-line treatments are available for patients who fail permethrin or pyrethrin treatment, but some of these alternative medications have patient safety concerns, whereas others require frequent treatments. Efforts are needed to identify safe and effective treatments for resistant head lice. Ivermectin is already used as a pediatric medication for intestinal nematodes, and previous in vitro tests have suggested that this agent would be effective against resistant head lice.
This report included data from 2 parallel trials investigating the efficacy and safety of topical 0.5% ivermectin in treating head lice. Both studies were multicenter, randomized, double-blind, industry-sponsored trials. The studies were conducted during the 2010 calendar year and included 8 clinical sites each. The children were aged 6 months and older with head lice infestation. No other treatment, including combing, was provided during the study period. All children had at least 3 live lice identified on their enrollment assessment.
On day 1, the index patients were presented with a 4-ounce tube containing either the study drug or the inactive vehicle. They were instructed to apply the medication at home that day and to leave the medication on for 10 minutes, then rinse their hair with water. If a household contact was found to be infested, that individual was also treated with the same drug or placebo that the household index case received. The primary outcome was the percentage of patients who had no live lice identified on days 2, 8, and 15-17. The study team assessed for adverse events, including irritation, pruritus, erythema, or other skin side effects.
The 2 trials enrolled 145 and 144 patients, respectively. Most of the children were girls, with a mean age of 7.5 and 8.5 years, depending on group. Approximately 39% of the study population was of Latino or Hispanic ethnicity. Almost 96% of the population was white. When household contacts were included, 765 patients completed the studies.
In both studies, ivermectin treatment was associated with a much higher success rate on day 2 (95.5% in the 2 studies), day 8 (88.6% success rate), and day 15 (78.7% success rate) compared with control treatment effectiveness of 35.3% on day 2, 26.2% on day 8, and 22.2% on day 15. Adverse events overall were very rare, at approximately 1%. Itching, erythema, and excoriation were the most common adverse events. The frequency and the severity classifications of the adverse events were not different between the 2 groups. In addition to getting rid of live lice, the children in the treatment group were much less likely to experience pruritus by day 2, at a frequency of 45.3% vs 67.4% in the control children. Pariser and colleagues concluded that this single, 10-minute application of ivermectin was more effective than the control treatment in eliminating head lice infections.
These data suggest that topical ivermectin can be both a quick and very effective treatment. In an accompanying editorial, Chosidow and Giraudeau mention that it would have been easier to determine how ivermectin might fit into a clinician's armamentarium if the comparative agent had been an active one. In fact, they suggest that because of the lack of relative effectiveness or efficacy data, topical ivermectin should be considered a third-line treatment, after appropriate second-line treatments have been tried, according to the 2010 American Academy of Pediatrics published recommendations for therapy. The topic of head lice, particularly resistant head lice, is obviously a vexing one for clinicians. Eradicating Head Lice With a Pill, about the use of oral ivermectin for resistant head lice, was the second-most read Pediatric Viewpoint of 2010.
Abstract
Topical 0.5% Ivermectin Lotion for Treatment of Head Lice
Pariser DM, Meinking TL, Bell M, Ryan WG
N Engl J Med. 2012;367:1687-1693
Head lice resistance to the 2 groups of medications that have long been first-line treatments -- permethrin and pyrethrins -- is increasing. Second-line treatments are available for patients who fail permethrin or pyrethrin treatment, but some of these alternative medications have patient safety concerns, whereas others require frequent treatments. Efforts are needed to identify safe and effective treatments for resistant head lice. Ivermectin is already used as a pediatric medication for intestinal nematodes, and previous in vitro tests have suggested that this agent would be effective against resistant head lice.
This report included data from 2 parallel trials investigating the efficacy and safety of topical 0.5% ivermectin in treating head lice. Both studies were multicenter, randomized, double-blind, industry-sponsored trials. The studies were conducted during the 2010 calendar year and included 8 clinical sites each. The children were aged 6 months and older with head lice infestation. No other treatment, including combing, was provided during the study period. All children had at least 3 live lice identified on their enrollment assessment.
On day 1, the index patients were presented with a 4-ounce tube containing either the study drug or the inactive vehicle. They were instructed to apply the medication at home that day and to leave the medication on for 10 minutes, then rinse their hair with water. If a household contact was found to be infested, that individual was also treated with the same drug or placebo that the household index case received. The primary outcome was the percentage of patients who had no live lice identified on days 2, 8, and 15-17. The study team assessed for adverse events, including irritation, pruritus, erythema, or other skin side effects.
The 2 trials enrolled 145 and 144 patients, respectively. Most of the children were girls, with a mean age of 7.5 and 8.5 years, depending on group. Approximately 39% of the study population was of Latino or Hispanic ethnicity. Almost 96% of the population was white. When household contacts were included, 765 patients completed the studies.
In both studies, ivermectin treatment was associated with a much higher success rate on day 2 (95.5% in the 2 studies), day 8 (88.6% success rate), and day 15 (78.7% success rate) compared with control treatment effectiveness of 35.3% on day 2, 26.2% on day 8, and 22.2% on day 15. Adverse events overall were very rare, at approximately 1%. Itching, erythema, and excoriation were the most common adverse events. The frequency and the severity classifications of the adverse events were not different between the 2 groups. In addition to getting rid of live lice, the children in the treatment group were much less likely to experience pruritus by day 2, at a frequency of 45.3% vs 67.4% in the control children. Pariser and colleagues concluded that this single, 10-minute application of ivermectin was more effective than the control treatment in eliminating head lice infections.
Viewpoint
These data suggest that topical ivermectin can be both a quick and very effective treatment. In an accompanying editorial, Chosidow and Giraudeau mention that it would have been easier to determine how ivermectin might fit into a clinician's armamentarium if the comparative agent had been an active one. In fact, they suggest that because of the lack of relative effectiveness or efficacy data, topical ivermectin should be considered a third-line treatment, after appropriate second-line treatments have been tried, according to the 2010 American Academy of Pediatrics published recommendations for therapy. The topic of head lice, particularly resistant head lice, is obviously a vexing one for clinicians. Eradicating Head Lice With a Pill, about the use of oral ivermectin for resistant head lice, was the second-most read Pediatric Viewpoint of 2010.
Abstract