The US Food and Drug Administration (FDA) has approved onabotulinumtoxinA (Botox, Allergan) to ease lower-limb spasticity in children and adolescents aged 2 years to 17 years, excluding spasticity caused by cerebral palsy (CP), the company announced.

"Lower limb spasticity can impact many aspects of a child's life and have a drastic influence on their overall development and quality of life," David Nicholson, Allergan's chief research and development officer, said in a news release.

The FDA approved Botox for lower-limb spasticity on the basis of safety and efficacy data from a phase 3 study involving more than 300 children aged 2 years or older with lower-limb spasticity.

Participants in the trial had CP, but the approved indication excludes lower-limb spasticity caused by CP, owing to marketing exclusivity by another company, Allergan said.

The approved recommended dose per treatment session is 4 to 8 units/kg divided among affected muscles of the lower limb. The total dose for pediatric patients should not exceed 8 units/kg body weight, or 300 units, whichever is lower.

When treating both lower limbs or upper and lower limbs in combination, the total dose for pediatric patients should not exceed 10 units/kg, or 340 units, whichever is lower, in a 3-month interval, the company said.

"Pediatric lower limb spasticity inhibits normal muscular movement and function and can result in delayed or impaired motor development, as well as difficulty with posture and positioning," Mark Gormley Jr, MD, of Gillette Children's Specialty Healthcare–St. Paul, said in the news release.

"Botox has a well-established safety and efficacy profile, and supports children and adolescents successfully manage both their upper and lower limb spasticity," said Gormley.