Spinosad 0.9% efficacious in scabies treatment

Topical spinosad was effective in eradicating scabies with a single treatment, according to two clinical studies.

“Scabies is a markedly pruritic, contagious skin infestation caused by the human itch mite Sarcoptes scabiei,” Jeffrey C. Seiler, MD, and colleagues wrote. “Given the prevalence of scabies in the overall population (approximately 300 million cases worldwide are reported annually), and in light of emerging permethrin resistance, the availability of a safe, well-tolerated, effective, single application treatment is critical.”

A topical suspension of spinosad 0.9%, which is associated with the excitation of the nervous system in insects, was previously approved by the FDA for the treatment of head lice infestations.

Two multicenter, randomized, double-blind, two-arm, vehicle-controlled, 28-day trials evaluated the topical drug in patients with scabies infestations. Subjects were to use the drug at home as a single application over the entire body from the neck to the toes as well as to the scalp (if balding) or hairline, temples and forehead. They were then told to wait 10 minutes before dressing and to wait at least 6 hours before showering or bathing.

Of those in the spinosad group, 78.1% had a complete cure of scabies at day 28 compared with 39.6% of those in the vehicle group (P < .0001).

In addition, the spinosad group showed greater efficacy at day 28 compared with vehicle based on percentages of index subjects with clinical and microscopic cures (P < .001).

“The combined results of the clinical studies presented herein show the treatment effect of spinosad 0.9% in the eradication of scabies and, specifically, demonstrate spinosad 0.9% is not equivalent to vehicle in regard to achieving complete cure 28 days after a single application,” the authors wrote.

Based in part on these data, earlier this year, the FDA approved spinosad 0.9% to treat scabies in patients aged 4 years and older.