Sponsors of drugs to treat partial onset seizures (POS) in pediatric patients should extend their trials to children as young as two, according to a final guidance from the FDA.

The guidance replaces a February 2018 draft guidance that placed the lower age limit at four years. A minimum of 100 pediatric patients of all ages two years and up should be exposed to the drug for at least six months of treatment, the guidance says.

The agency notes that safety data “generally cannot be extrapolated from adults to children,” so sponsors should conduct clinical studies to characterize the safety of the drug in pediatric patients two years of age and older with POS, “with all ages well-represented.”