Phase III clinical trial results demonstrate effectiveness of spinosad suspension

ParaPRO, LLC announced today the results of two Phase III clinical studies published online this month in the journal Pediatrics (Pediatrics 2009; 124:e389-e395) which concluded that a spinosad suspension was significantly more effective in eliminating head lice (pediculosis capitis) than permethrin. Permethrin, which is marketed under the brand name Nix, is the American Academy of Pediatrics’ recommended first-line medication for head lice.

The studies, in which the participants used the products at home, unsupervised, demonstrated that 0.9% spinosad was significantly more effective than 1% permethrin lice treatment in eliminating head lice. The majority of spinosad-treated participants were lice-free after only one application. In addition, treatment with spinosad did not require the time consuming, rigorous combing of nits (head lice eggs), in contrast to the comparator treatment permethrin (which was used according to its label instructions and required nit removal by combing). Both the spinosad and permethrin treatments were well tolerated with few adverse events reported.

“In these studies, spinosad eliminated head lice for most patients the first time. This meant these caregivers only needed to apply a single treatment and did not need to spend time combing out nits in order to complete the treatment,” said Dow Stough, M.D., Burke Pharmaceutical Research and an investigator in the studies. “This is significant because convenience and compliance are important issues in treating and getting rid of head lice.”

The U.S. Centers for Disease Control and Prevention estimates that there are between 6 to 12 million cases of head lice infestations each year. Most occur in children 3 to 12 years old. Head lice are tiny, wingless insects that live on the human scalp and spread between people by head-to-head contact or the sharing of hats, combs, brushes or towels. In most cases, infestations are not linked to poor hygiene; therefore, they can occur in anyone. Adult head lice are about as big as sesame seeds (2-3 mm long) and infest the human head and neck and also attach their nits (eggs) to the base of the hair shaft. Lice move by crawling; they cannot hop or fly.

Costs associated with head lice infestations are estimated to be as high as $1 billion per year in the United States alone. Direct costs include treatments and clinic visits, and indirect costs range from school nurse time to school absenteeism to lost wages.

Currently, there are many head lice treatments available over-the-counter and by prescription. The therapies most commonly recommended by pediatricians require the painstaking removal of nits. If viable nits remain, re-infestation could occur when the eggs hatch.

Results of these and other studies have been submitted to the U.S. Food and Drug Administration (FDA) for approval to market spinosad suspension as a prescription product. ParaPRO is seeking approval to market the product under the name NatrOVA™.

In the Phase III studies, the subjects treated with spinosad were instructed to apply the product to dry hair, leave it on for 10 minutes, and then rinse with water.

Clinical Trial Design

The two Phase III, multi-center, randomized, evaluator/investigator-blinded, parallel-group studies compared 0.9% spinosad without a nit-combing step with 1% permethrin with combing (according to that product’s instructions) in 1,038 boys and girls six months of age and older with pediculosis capitis.⁵

The studies were conducted simultaneously at 12 U.S. geographically dispersed clinical research centers from September 2007 to April 2008. In 391 total households, the youngest household member having three or more live lice present was designated the primary participant.

Other household members with lice received the same treatment as the primary member. Participants used the product at home once or twice during the 21-day home-use period, based on complete eradication of lice after a single use or the presence of lice requiring a second treatment. Scalp evaluations for live lice were performed at baseline, day 7, and day 14 (and day 21 for participants treated twice). The primary efficacy end point was the proportion of lice-free primary participants 14 days after the last treatment. The secondary efficacy end point looked at how many enrolled subjects in the household (primary and non-primary) required two versus one treatment.

Clinical Trial Results

A total of 84.6% (study 1) and 86.7% (study 2) of spinosad-treated participants were assessed to be lice-free 14 days after the last treatment compared with 44.9% and 42.9% treated with permethrin (both studies: P<0.001). Most participants in the spinosad groups (63.8% and 86.2%) required one application, whereas most participants in the permethrin groups (60.3% and 64.5%) required two applications, the maximum allowed by the protocol.

Few treatment-related adverse events were reported for either medication, and those occurring were mild to moderate in severity and included eye irritation (2.2% of spinosad vs. 3.3% of permethrin subjects) and application-site erythema/irritation (4.0% of spinosad vs. 8.3% of permethrin subjects). No participants discontinued from the studies because of an adverse event.