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.

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.