A Randomized, Investigator‐Blinded, Time‐Ranging Study of the Comparative Efficacy of 0.5% Malathion Gel Versus Ovide^®Lotion (0.5% Malathion) or Nix^® Crème Rinse (1% Permethrin) Used as Labeled, for the Treatment of Head Lice

Abstract

One hundred seventy-two subjects with head lice participated in a five-way, investigator-blinded, parallel-group, active-controlled study comparing 0.5% malathion gel (30, 60, and 90 minutes applications), Ovide Lotion (0.5% malathion), and Nix Crème Rinse (1% permethrin). All subjects were treated on day 1. Participants were reevaluated at day 8 +/- 1 and those with live lice were retreated with the same product, for the same duration as day 1. Cure, defined as the absence of live lice, was evaluated 14 +/- 2 days after the last treatment and 161 subjects completed the study according to the protocol. Compared to Nix, treatment success rates were statistically superior for all malathion gel and Ovide groups. Retreatment rate for Nix was 70%, which was statistically more than the malathion groups. The highest treatment success rates were observed for the 30-minute malathion gel (98% intent-to-treat and 100% per-protocol [PP]) and the 8 to 12 hour Ovide application (97% intent-to-treat and 100% PP). In conclusion, the 30-minute malathion gel, which contains the same ingredients and concentrations as Ovide, provides comparable efficacy, offers increased safety and is more cosmetically acceptable than Ovide.

Ex vivo effectiveness of French over-the-counter products against head lice (Pediculus humanus capitis De Geer, 1778)

“…The clinical efficacy of malathion was tested in several clinical trials (Mathias et al 1984;Meinking et al 2004Meinking et al , 2007, and it is considered an effective active ingredient in previous systematic reviews (Vander Stichele et al 1995;Dodd 2000). There are clinical indications that resistance to malathion is rising Bouvresse 2012).…”

Head Lice Treatments and School Policies in the US in an Era of Emerging Resistance

“…A patient/caregiver perspective was applied since most of the head lice treatments are sold as OTC treatments, which makes the caregiver's perspective desirable for this analysis. A time horizon of 2 weeks, the usual time employed in clinical evaluations of treatment effectiveness, [11,12] …”

“…Probabilities of treatment success or failure of permethrin 1% and malathion 0.5% were based on a report by Meinking et al, [11] who described the current success rates of these two remedies (table I). The probabilities of the combing strategy were derived from the study of Roberts et al [8] Based on the finding in the literature [28] that combing success rates should not be evaluated before at least 2 weeks of treatment have elapsed (because of the overall poor success rates of this approach), a probability of 0 for success of lice eradication after a single week of combing treatment was assumed.…”

“…Permethrin 1% second-week cure probabilities [9,11] 0.214 0.214 0.98 school for the first week of treatment. However, an assumption was made that a student will have to lose 1 school day during the second week of treatment in the case of treatment failure after the first week, based on current practices in the US [36] and other countries.…”

“…[10] Yet, concerns about emerging head lice resistance to permethrin worldwide have been raised. [11][12][13][14][15][16][17][18] It is also clear that as permethrin resistance increases, its effectiveness for lice treatment is correspondingly reduced. Moreover, the information regarding the specific susceptibility or resistance of head lice in a particular geographical area is not readily available for both the public and health providers.…”